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ETSITS102 929V2.1.2 



(2013-03) 




Speech and multimedia Transmission Quality (STQ); 

Procedures for the identification and selection of 

common modes of de-jitter buffers and echo cancellers 



ETSI TS 102 929 V2.1.2 (2013-03) 



Reference 



RTS/STQ-00208 
Keywords 



jitter buffer, QoS, quality 



ETSI 

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ETSI 



ETSI TS 102 929 V2.1.2 (2013-03) 



Contents 



Intellectual Property Rights 5 

Foreword 5 

Introduction 5 

1 Scope 6 

2 References 6 

2.1 Normative references 6 

2.2 Informative references 7 

3 Definitions and abbreviations 7 

3.1 Definitions 7 

3.2 Abbreviations 8 

4 Characteristics of jitter buffers 8 

4.1 General 8 

4.1.1 Jitter Buffers 9 

4.2 Purpose, operation and environment 9 

4.3 External enabling of fixed jitter buffers 9 

5 Characteristics of VBD-mode switching of jitter buffers 10 

5.1 General 10 

5.2 Detector characteristics 11 

5.2.1 Detector characteristics for frequency range of 2 100 Hz + 21 Hz 11 

5.2.2 Detector characteristics for dual-frequency tones 1 375 Hz + 2 002 Hz and 1 529 Hz + 2 225 Hz 
(Recommendation ITU-T V.Sbis) 11 

5.2.3 Detector characteristics for frequencies 980 Hz, 1 180 Hz, 1 650 Hz and 1 850Hz(V.21) 12 

5.2.4 Detector characteristics for 2 100 Hz amplitude-modulated by a sinewave at 15 Hz, 2 100 Hz 
amplitude-modulated by a sinewave at 15 Hz with phase reversals, 1 300 Hz and 1 100 Hz (V.8) 12 

5.2.5 Detector characteristics for V.22 13 

5.2.6 Detector characteristics for 2 100 Hz with phase reversals (V.25) 14 

5.2.7 Detector characteristics for Recommendation ITU-T V.32/V.32bis 17 

5.2.8 Detector characteristics for Recommendation ITU-T T.30 17 

5.2.9 Noise tolerance 18 

5.2.10 Operate time 18 

5.2.11 False operation due to speech signals 18 

5.2.12 Release time 19 

5.2.13 Other considerations 19 

6 Activation of jitter buffer for VBD 19 

7 Activation of jitter buffer for 64 kbit/s bit sequence (UDI) 21 

8 Requirements for values of jitter buffers 22 

8.1 Fixed jitter buffers 22 

8.2 Adaptive jitter buffers 22 

8.3 Activation procedure into the fixed mode 22 

8.4 Transition from VBD to Voice mode (Recommendation ITU-T V.152) 22 

8.5 Handling of Jitter Buffer in case of lost or late packets 23 

9 Echo canceller 24 

9.1 Characteristics of an echo canceller tone disabler (Recommendation ITU-T G.168) 24 

9.1.1 General 24 

9.1.2 Detector characteristics 25 

9.1.3 Phase reversal detection 26 

9.1.4 Guard band characteristics 26 

9.1.5 Noise tolerance 26 

9.1.6 Holding-band characteristics 27 

9.1.7 Operate time 27 



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9.1.8 False operation due to speech currents 27 

9.1.9 False operation due to data signals 27 

9.1.10 Release time 27 

9.1.11 Other considerations 27 

Annex A (normative): Jitter buffer Facsimile tests 29 

A.l Measurement method 29 

Annex B (normative): Echo canceller Tests 56 

B.l Introduction 56 

B.1.1 Signals used 56 

B.1.2 Preparatory measurements 56 

B.2 Tests with echo simulation at Interface B 57 

B.2.1 Tests with test signals based on Composite Source Signal (CSS) 58 

B.2. 1.1 Answer tones + C 16 58 

B.2. 1.2 Answer tones + first fax frame + C16 59 

B.2. 1.3 Tests with test signals based on the Use of the CI call signal and exchange of CM/JM menu signals 

+ C16 60 

B.2. 1.4 Tests with test signals based on DTMF 61 

B.2. 1.4.1 Answer tones + D16 61 

B.2. 1 .5 Tests with test signals based on the Use of the CI call signal and exchange of CM/JM menu signals 

+ D16 62 

B.3 Tests with echo simulation at Interface A 62 

B.3.1 Tests with test signals based on CSS 64 

B.3. 1.1 Answer tones + C 16 64 

B.3. 1.2 Answer tones + first fax frame + C16 65 

B.3. 1 .3 Tests with test signals based on the Use of the CI call signal and exchange of CM/JM menu signals 

+ C16 67 

B.3. 1.4 Tests with test signals based on DTMF 67 

B.3. 1.4.1 Answer tones + D16 67 

B.3. 1.5 Tests with test signals based on the Use of the CI call signal and exchange of CM/JM menu signals 

+ D16 68 

B.4 Tests with test signals based on the data rate change between V.34 and V.17 Fax Terminals 69 

Annex C (informative): Features of V.17 Fax and V.34 Fax 71 

C.l Features of V.17 Fax (V.17 Fax Modem) 71 

C.2 V.34 High-Speed Fax 71 

C.2.1 Features 71 

C.2.2 The Recommendation ITU-T V.34 Fax Standard 71 

C.3 The V.34 Fax Connection and Session 72 

C.4 ECM as a Mandatory Feature 73 

History 74 



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Intellectual Property Rights 



IPRs essential or potentially essential to the present document may have been declared to ETSI. The information 
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found 
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in 
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web 
server ( http://ipr.etsi.org ). 

Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee 
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web 
server) which are, or may be, or may become, essential to the present document. 



Foreword 

This Technical Specification (TS) has been produced by ETSI Technical Committee Speech and multimedia 
Transmission Quality (STQ). 



Introduction 



The present document describes the characteristics of a jitter buffer, including the requirement for in-band tone 
activating and other control mechanisms. 



ETSI 



ETSI TS 102 929 V2.1.2 (2013-03) 



Scope 



Jitter buffers and echo cancellers have a major effect on voice and data transmission quality in telecommunication 
networks. They affect the transmission of voice band, data, fax, text telephones and transmission of unrestricted digital 
information (UDI). Since the requirements for the settings of jitter buffers and echo cancellers differ for different 
services, the present document describes the activation and mode switching procedures of jitter buffers and echo 
cancellers, including the requirement for in-band tone activating and other control mechanisms. 

The current version of the present document contains additional Jitter Buffer requirements for the transmission of 
V. 152, Echo Canceller Tests and Jitter Buffer Tests. 

The present document does not apply for fax transmissions with Recommendation ITU-T T.38 [i.7]. 

It is understood that the clock accuracy of all elements involved is sufficiently high for application of the present 
document. 



References 



References are either specific (identified by date of publication and/or edition number or version number) or 
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the 
reference document (including any amendments) applies. 

Referenced documents which are not found to be publicly available in the expected location might be found at 
http://docbox.etsi.org/Reference . 

NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee 
their long term validity. 

2.1 Normative references 

The following referenced documents are necessary for the application of the present document. 

[1] Recommendation ITU-T V.8 (2000): "Procedures for starting sessions of data transmission over 

the public switched telephone network". 

[2] Recommendation ITU-T V.Sbis (2000): "Procedures for the identification and selection of 

common modes of operation between data circuit-terminating equipments (DCEs) and between 
data terminal equipments (DTEs) over the public switched telephone network and on leased point 
to-point telephone-type circuits". 

[3] Recommendation ITU-T G. 168: "Digital network echo cancellers". 

[4] Recommendation ITU-T V.21 (1988): "300 bits per second duplex modem standardized for use in 

the general switched telephone network". 

[5] Recommendation ITU-T V.22 (1988): "1200 bits per second duplex modem standardized for use 

in the general switched telephone network and on point-to-point 2-wire leased telephone-type 

circuits". 

[6] Recommendation ITU-T V.25 (1996): "Automatic answering equipment and general procedures 

for automatic calling equipment on the general switched telephone network including procedures 
for disabling of echo control devices for both manually and automatically estabUshed calls". 

[7] Recommendation ITU-T V.32 (1993): "A family of 2-wire, duplex modems operating at data 

signalling rates of up to 9600 bit/s for use on the general switched telephone network and on 
leased telephone-type circuits". 

[8] Recommendation ITU-T V.32bis (1991): "A duplex modem operating at data signalling rates of up 

to 14 400 bit/s for use on the general switched telephone network and on leased point-to-point 
2-wire telephone-type circuits". 



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7 ETSI TS 1 02 929 V2.1 .2 (201 3-03) 

[9] Recommendation ITU-T V.152 (2010): "Procedures for supporting voice-band data over IP 

Networks". 

2.2 Informative references 

The following referenced documents are not necessary for the application of the present document but they assist the 
user with regard to a particular subject area. 

[i.l] Recommendation ITU-T G. 164: "Echo Suppressors". 

[i.2] Recommendation ITU-T G.165: "Echo Cancellers". 

[i.3] Recommendation ITU-T V.2 (1988): "Power levels for data transmission over telephone lines". 

[i.4] Void. 

[i.5] Recommendation ITU-T G.131 (1996): "Control of talker echo". 

[i.6] Recommendation ITU-T Q. 1 15. 1 (1999): "Logic for the control of echo control 

devices/functions" . 

[i.7] Recommendation ITU-T T.38 (2010): "Procedures for real-time Group 3 facsimile communication 

over IP networks". 

[i.8] Introduction to V.34 High-Speed Fax. 

NOTE: Website: http://www.gaoresearch.com/V34FaxA^34Fax.php , latest access 4 July 2012. 

[i.9] Recommendation ITU-T V.34 (1998): "A modem operating at data signalling rates of up to 

33 600 bit/s for use on the general switched telephone network and on leased point-to-point 2-wire 
telephone-type circuits". 

[i.lO] Recommendation ITU-T T.30: "Procedures for document facsimile transmission in the general 

switched telephone network". 

[i.ll] Recommendation ITU-T V. 150.1: "Modem-over-IP networks: Procedures for the end-to-end 

connection of V-series DCEs". 

[i. 12] Recommendation ITU-T V. 18: "Procedures for starting sessions of data transmission over the 

public switched telephone network". 

[i.l3] Recommendation ITU-T G.711: "Pulse code modulation (PCM) of voice frequencies". 



3 Definitions and abbreviations 

3.1 Definitions 

For the purposes of the present document, the following terms and definitions apply: 

acoustic echo: acoustic echoes consist of reflected signals caused by acoustic environments 

NOTE: In these acoustic environments, an echo path is introduced by the acoustic path from the loudspeaker or 
earpiece to the microphone, e.g. echo created from hands-free speakerphones [3]. 

echo canceller: voice-operated device placed in the 4- wire portion of a circuit and used for reducing the cancelled end 
echo present on the send path by subtracting an estimation of that echo from the cancelled end echo [3] 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Non-Linear Processor (NLP): device having a defined suppression threshold level and in which: 

a) signals having a level detected as being below the threshold are suppressed; and 

b) signals having a level detected as being above the threshold are passed although the signal may be distorted 

NOTE: The present document assumes an echo canceller is equipped with an NLP function that can be enabled or 
disabled when performing the tests defined in the present document. An NLP function can be enabled or 
disabled by the user (for the purpose of performing a particular test), or may also be disabled upon 
detection of an appropriate disabling tone (e.g. 2 100 Hz) [3]. 

3.2 Abbreviations 

For the purposes of the present document, the following abbreviations apply: 

ANM Answer Message 

CM Call Menu signal 

CM/JM Call Menu signal/Joint Menu signa 

CSS Composite Source Signal 

CT Calling Tone 

DCE Data Communication Equipment 

DJB De Jitter Buffer 

DTMF Dual-Tone Multi-Frequency signaling 

EC Echo Canceller 

ECM Error Correction Mode, 

ERL Echo Return Loss 

ERLE Echo Return Loss Enhancement 

GSTN General Switched Telephone Network 

IAD Integrated Access Device 

IP Internet Protocol 

ISUP ISDN User Part 

ITU-T International Telecommunication Union - Telecommunication Standardization Sector 

JB Jitter Buffer 

JBD Jitter Buffer Delay 

JBS Jitter Buffer Size 

JM Joint Menu signal 

MGC Media Gateway Controller 

MGW Media Gateway 

MSAN Multi Service Access Nodes 

NLP Non-Linear Processor 

PCM Pulse code modulation 

PLC Packet loss concealment 

PSTN Public Switched Telephone Network 

QAM Quadrature Amplitude Modulation 

RCV Received 

RTP Real Time Protocol 

SIP Session Initiation Protocol 

TDM Time division multiplexing 

UDI Unrestricted Digital Information 

VBD Voice Band Data 



Characteristics of jitter buffers 



4.1 



General 



The present document describes the activation procedures of a jitter buffer, including the requirement for in-band tone 
activating and other control mechanisms. The jitter buffers are assumed to be dynamic jitter buffers and fixed jitter 
buffers. Fixed jitter buffers shall be provided for fax and voice band data and 64 kbit/s bit sequence (UDI). 



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4.1.1 Jitter Buffers 



A jitter buffer is designed to remove the effects of jitter from the decoded voice stream, buffering each arriving packet 
for a short interval before playing it out synchronously. A fixed jitter buffer maintains a constant size whereas an 
adaptive jitter buffer has the capability of adjusting its size dynamically in order to optimize the delay/discard 
trade-off The disadvantage of adaptive jitter buffer is that a part of the jitter budget is transferred to the user. While 
the human perception of audio delay variation is low, modem and fax applications are extremely sensitive to delay 
variation in the audio path. For this reason adaptive jitter buffer are not applicable for fax and modem transmission. 
Fixed jitter buffers try to maintain a constant End-to-End audio delay. 

Jitter Buffer Size 



Voice 
sample 
arriving 



Jitter Buffer Delay 

Figure 1 : Jitter Buffer Size and Delay 



Voice 
sample 
leaving 



Jitter Buffer Size (JBS): The maximum amount of time packets can stay in the buffer. 

Jitter Buffer Delay (JBD): The jitter buffer delay is also called de-jitter delay, holding time or play-out delay. It 
corresponds to the time packets stay in the buffer, which is less than the jitter buffer size. The time of departure of each 
packet is determined by reading out the timestamp information provided by RTF. 

4.2 Purpose, operation and environment 

For proper operation for VBD-services, Jitter buffers have the following fundamental requirements: 

1) fast and correct switching between dynamic and fix jitter buffer mode; 

2) proper operation during facsimile and data transmissions. 

For proper operation of speech services in good quality, false detection of tones (e.g. from answering machines, call 
centers or speech) has to be minimized. 

NOTE: It may be necessary to make a balancing between quality requirements of VBD and speech services. 

4.3 External enabling of fixed jitter buffers 

The fixed jitter buffer for 64 kbit/s bit sequence (UDI) and V.152 VBD shall be activated directly by signalization. 



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5 Characteristics of VBD-mode switching of jitter 

buffers 

5.1 General 

The jitter buffer covered by the present document should be equipped with a tone detector that conforms to this clause. 

• The change of the jitter buffer to VBD-mode should be based on the following signals (mostly taken out of 
Recommendation ITU-T V.152 [9]) For Facsimile applications: 

CED as per Recommendation ITU-T T.30 [i.lO] 

ANSam as per Recommendation ITU-T V.8 [1] 

Preamble as per Recommendation ITU-T T.30 [i.lO], section 5.3.1 

CNG as per Recommendation ITU-T T.30 [i.lO] 

• For Modem applications: 

ANS as per Recommendation ITU-T V.8 [1] 

ANSam as per Recommendation ITU-T V.8 [1] 

/ANS as per Recommendation ITU-T V.25 [6] 

2 225 Hz answer tone as per Recommendation ITU-T V. 150.1 [i.ll], appendix VI 

Unscrambled binary ones signal as per Recommendation ITU-T V.22 [5] 

CI signals that precede ANSam, as per Recommendations ITU-T V.8 [1] and V.21 [4] 

Dual-frequency tones (1 375 Hz H- 2 002 Hz and 1 529 Hz H- 2 225 Hz) as per 
Recommendation ITU-T V.8bis [2] 

• For Text Telephony applications: 

ANS as per Recommendation ITU-T V.8 [1] 

ANSam as per Recommendation ITU-T V.8 [1] 

Text telephone signals as defined by Recommendation ITU-T V.18 [i.l2], section 5.1.1 

CI signals that precede ANSam, as per Recommendation ITU-T V.8 [1] 

CT (Calling Tone) signals that precede ANS, as per Recommendation ITU-T V.25 [6] 

Initiating Segment 1 dual tones (1 375 Hz & 2 002 Hz) as per Recommendation ITU-T V.8bis [2] 



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5.2 



Detector characteristics 



5.2.1 Detector characteristics for frequency range of 2 1 00 Hz ± 21 Hz 

The tone detector shall detect a tone in the frequency range of 2 100 Hz ± 21 Hz (see Recommendation 
ITU-T V.21 [4]). The detection channel bandwidth should be chosen wide enough to encompass this tone (and possibly 
other tones used within national networks). At the same time, the detection channel bandwidth should be such that, in 
conjunction with guard action and timing, adequate protection is provided against false operation of the detector by 
speech signals. The detector channel sensitivity (threshold level) should be such that the detector will operate on the 
lowest expected power of the tone. The band characteristics shown in figure 2 will permit changing the jitter buffer 
behaviour by the 2 100 Hz tone as well as others used in North America. The figure indicates that in the frequency band 
2 079 Hz to 2 121 Hz detection shall be possible whilst in the band 1 900 Hz to 2 350 Hz detection may be possible. 
Providing that only the recommended 2 100 Hz tone is used internationally, interference with signalling equipment will 
be avoided. The dynamic range of the detector should be consistent with the input levels as specified in 
Recommendation ITU-T V.2 [i.3] with allowances for variation introduced by the public switched telephone network. 




1900 2100 2350 

2075 1121 

Fteqjucucy (Hz) 

Figure 2: Required band characteristics 



5.2.2 



Detector characteristics for dual-frequency tones 1 375 Hz + 

2 002 Hz and 1 529 Hz + 2 225 Hz (Recommendation ITU-T V.Sbis) 



The tone detector shall detect two tone segments. The first segment consists of a dual-frequency tone held for 400 ms. 

The specific frequencies 1 375 Hz H- 2 002 Hz are used from the initiator, the specific frequencies 

1 529 Hz H- 2 225 Hz from the responder in a transaction. When using the telephone-event payload, the VSblSeg and 

VSbRSeg events in table 1 represent the first segment of any V.Sbis signal in the initiating and responding case, 

respectively. 

Table 1 : Events for V.Sbis signals 



Signal 


Frequency 


VSblSeg 


1 375 Hz + 2 002 Hz 


VSbRSeg 


1 529 Hz + 2 225 Hz 



The tolerance of the frequency of all tones is be +250 ppm of the nominal value. 
The tolerance of the duration of the tone segments shall be +2 %. 



ETSI 



12 



ETSI TS 102 929 V2.1.2 (2013-03) 



The detection channel bandwidth should be chosen wide enough to encompass this tones (and possibly other tones used 
within national networks). At the same time, the detection channel bandwidth should be such that, in conjunction with 
guard action and timing, adequate protection is provided against false operation of the detector by speech signals. The 
detector channel sensitivity (threshold level) should be such that the detector will operate on the lowest expected power 
of the tone. 

5.2.3 Detector characteristics for frequencies 980 Hz, 1 180 Hz, 1 650 Hz 
and 1 850Hz(V.21) 

The tone detector shall detect the frequencies 980 Hz for '1' (mark) and 1 180 Hz for '0' (space) (low channel uses) and 
the frequencies 1 650 Hz for '1' and 1 850 Hz for '0' (high channel uses). The frequency deviation is +100 Hz. 

The detection channel bandwidth should be chosen wide enough to encompass this tones (and possibly other tones used 
within national networks). At the same time, the detection channel bandwidth should be such that, in conjunction with 
guard action and timing, adequate protection is provided against false operation of the detector by speech signals. The 
detector channel sensitivity (threshold level) should be such that the detector will operate on the lowest expected power 
of the tone. 

Table 2: Events for V.21 Signals 



Signal 


Frequency (Hz) 


V.21 channel 1, 
'0' bit 


1 180 


V.21 channel 1, 
'1'bit 


980 


V.21 channel 2, 
'0' bit 


1 850 


V.21 channel 2, 
'1'bit 


1 650 



5.2.4 



Detector cinaracteristics for 2 100 Hz amplitude-modulated by a 
sinewave at 15 Hz, 2 100 Hz amplitude-modulated by a sinewave at 
15 Hz with phase reversals, 1 300 Hz and 1 100 Hz (V.8) 



To activate the Jitter buffer at calling end respectively called end for procedures according to Recommendation 
ITU-T V.8 [1], the tone detector shall detect frequencies described in table 3. 

Table 3: Events for V.8 Signals 



Signal 


Frequency 


ANSam 


2 100 Hz amplitude-modulated by a sinewave at 15 Hz 


/ANSam 


2 100 Hz amplitude-modulated by a sinewave at 15 Hz with 
phase reversals at an interval of 450 ± 25 ms 


CI 


(V.21 bits) (see note) 


CT 


1 300 Hz 


CNG 


1 100 Hz 


NOTE: CI is transmitted from the calling DCE with a regular ON/OFF cadence. The ON periods shall be not less than 
3 periods of the CI sequence, and not greater than 2 s in duration; the OFF periods shall be not less than 0,4 s 
and not greater than 2 s in duration. 
A CI sequence consists of 10 ONEs followed by 10 synchronization bits and the call function octet. 



To initiate a session of data transmission on the PSTN according Recommendation ITU-T V.8 [1] a DCE transmits 
either CI, CT, CNG or no signal. Signal CI is a V.8 alternative to call tone CT, and is coded to indicate a call function. 
The term "call signal" is used hereinafter to refer to CI, CT or CNG. 

Modified answer tone ANSam consists of a sinewave signal at 2 100 + 1 Hz with phase reversals at an interval of 
450 + 25 ms, amplitude-modulated by a sinewave at 15 + 0,1 Hz. The modulated envelope shall range in amplitude 
between (0,8 + 0,01) and (1,2 + 0,01) times its average amplitude. 

The average transmitted power shall be in accordance with Recommendation ITU-T V.2 [i.3]. 



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ETSI TS 102 929 V2.1.2 (2013-03) 



The average power outside the band 2 100 + 200 Hz produced by using an approximation to the 15 Hz sinewave 
envelope is at least 24 dB below the average power within that band. 





Ir 




, T.^ 




75 ± 






' 




0,0,0, ... 




CM, CM, CM,... 


CJ 









sigC 



(Note) 



/ \ / \ 



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ANSam 



IM,JNL.JM, 



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aOJa 



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Figure 3: Use of the CI call signal and exchange of CM/JM menu signals 
(Figure 1 from Recommendation ITU-T V.8 [1]) 

The detection channel bandwidth should be chosen wide enough to encompass this tones (and possibly other tones used 
within national networks). At the same time, the detection channel bandwidth should be such that, in conjunction with 
guard action and timing, adequate protection is provided against false operation of the detector by speech signals. The 
detector channel sensitivity (threshold level) should be such that the detector will operate on the lowest expected power 
of the tone. 

5.2.5 Detector characteristics for V.22 

To activate the Jitter buffer at calling end respectively called end for procedures according to Recommendation 
ITU-T V.22 [5], the detector shall detect unscrambled binary 1 for 155 + 50 ms from the calling terminal and 
Recommendation ITU-T V.25 [6] answer sequence from the called terminal. 

Table 4: Events for V.22/V.25 answer sequence 



Signal 


Frequency 


Answer tone (ANS) 


2 100 Hz 


unscrambled binary 1 for 155 ± 50 ms 
from the calling terminal 





ETSI 



14 



ETSI TS 102 929 V2.1.2 (2013-03) 



















«vait4SGtiain 




Transmitted linfitignal 


aisnce 


Scmnbbd 
binary 1 






Data 




>4aOm. 
t to linft 


C»tKt umcramblad 
biMry 1 in l&S * SOms 






104 








ConnK 


Peuct 

uramblad 

biniry 1 

in 270 ± 40 mi 

Ciamped to 
binary 1 


Wait 
785 1 10 ms 






107 


t09 




106» 




Bint- 
r» 1 








t)at« 




Answer mode modem 


















SiJsncs 


2100 H; 
3300 t 700 ms 




Unterambl«d binary 1 
sndiaOOHE 




Scrambted binary 1 
and 1300 Hz 


Data ai>( 














7S±20™ 
107 










Connect to Una 


Detect 
Kramblpd 
binory 1 or 
binary in 


Wait 766 ±10 mi 






106"' 




jvote - Binary 
comes from 
^tentative C 






109 

Binary 1 








^^ AuumM cizcvil 105 htsbeentnnudon. 


1P4 clampQd tn binary 1 


Data 










aaTT-H«» 

















Tfsnsmiited ltn« signal 


Walt4Sei10mi 




Scrambled 
binary 1 






Daa 




llilH , * 

DetBC 
binary 


unscrambied 
1 in 166 t 60 ma 




104 










Detect scramble 

binary 1 

in 270 1 40 m> 


, """ 


765 1 10 ™ 






107 






109 


ioe"t 






Ciamt»dto ^ 

hi nary 1 ^ 


Data 




Answer mods mo<fefn 










Transmitted tins lignai 


UntcramblHl binary l 
and 1800 Hz 




Scrambled binary 1 
and 1800 Hz 


Datooni 


I1800HJ 










ioe»> 

109 




ConnK 


1 to line 




Detect scrainblBi 
binary 1 or 
Unary In 
270 ± 40 me 

JVole - Biiuiy 
comu from 
Alteniattve C 


Wail 7eS t 10 rt« 






107 




















Binary 1 




*^ Assumes drcuit 105 has been tamed on 




10*clamp«)1 


a binary 1 


Data 



Figure 4: l-landshalte sequence for Alternatives A and B 
(with V.25 auto-answering) 

5.2.6 Detector characteristics for 2 1 00 Hz witin pinase reversals (V.25) 

Recommendation ITU-T V.25 [6] specifies the exchange of two tone signals: CT and ANS. 

To activate the Jitter buffer at calling end respectively called end for procedures according to Recommendation 
ITU-T V.25 [6], the tone detector shall detect frequencies described in table 5. 



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Table 5: Events for V.25 Signals 



Signal 


Frequency 


Answer tone (ANS) 


2 100 Hz 


/ANS 


2 1 00 Hz with phase reversals at an interval of 
450 ± 25 ms 


CT 


1 300 Hz 



The calling tone (CT) tone is transmitted from the calling end. This may be 1 300 Hz or any tone corresponding to 
binary 1 of the DCE. The calling tone and calling station response should not contain power in the band 
2 100 + 250 Hz. The power levels of the signals specified in the present document shall conform to the levels specified 
in Recommendation ITU-T V.2 [i.3]. 

Calling Tone (CT) consists of a series of interrupted bursts of 1 300-Hz tone, on for a duration of not less than 0,5 s and 
not more than 0,7 s and off for a duration of not less than 1,5 s and not more than 2,0 s. 



Calling 
tone 

0,5-0,7 



r- 



152* 



0,4-0,7* 



DCE under 

control of the 

DTE, CT 107 ON 



13 i 07 s 



Answering tone 
2100 Hz 



0«s 
4 ^ 



0,9 5 

H ► 



0,1 - 0.8s 
A ► 



I 



I 



Not sufficiertto 

disable €Cho 
suppressors 



Network inter- 
action time 



Tolerance T^izoms 



210C Hz 

detection tin^e 



Figure 5: Timing of line signals 



Gapforreoogniifng 

the end of the 

2100 Hz answering 

tone 



caTT-AJ5«S 



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Timing at 
answering 
daw 
station 



Calling tone burst truncated = I 



Timing at _______^_ 

calling Calling tone 

data burst 

station ^^__.^^^_ 



t 5= 400 ms 

!-• H 



ANS detscted 
for s 100 ms 



Answering 
data station 
connected 
to line 



1.B-2.SS Silent 
interval 



Calling station 
response 



Calling station 
response 
detected 
for a 100 ms 



— ► U— 



ANS":' 



: 4.0 S tl) 



□CE under 
control of 
tbs CfTE, 
CT 107 ON l") 



Answer modem 
Ifne signal 



Figure 6: Timing of line signals - Optional calling station response 



Calling tone burst tfuncated^* 



Timing at 
calling 
data 
station 




Answering 
data station 
connected 
tg line 



Timing 3t 
answering 
data 
i tat ion 



1,6-2, 5=5 Fiilftnt 
interval 



ANS=' 



P l6 



AWS 



->U 



Calling station 
response 



Calling station 
response 

detected 

for ^ 100 ms _ 



APIS 



T = i60 1 2Bma 



i 4.0b<Si 



DCE under 
control of 

ttifl DTE, 

CT 107 ON >•' 



Ar^&wer modem 
line siqnsi 



75 ± 20 ms 



CCITT, 413^0 



°' If ANS is deteaed during a calling tone burst, the burst maj be truncated. If it is not truncated, the calling 

station response m list be delayed until al least 1 second after the end of the burst. 
"' See §3, 20 for exception. 

'> ANS denotes the answer lone, ANS denotes the answer tone with its phase reversed. 
•" The answer tone dntation must be at least 2.6 seconds if a calling station response is not rtceived. 



Figure 7: Timing of line signals, optional provision for echo canceller disabling 

and for calling station response 



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5.2.7 Detector characteristics for Recommendation ITU-T V.32/V.32bis 

Operating over the public telephone network, the start-up follows the V.25 answering procedure (see clause 5.2.4). 

Recommendation ITU-T V.32 [7] is a modem using phase-shift keying with quadrature amplitude modulation. It 
operates on a carrier at 1 800 Hz, modulated at 2 400 symbols/s. The basic data rates for Recommendation 
ITU-T V.32 [7] are 4 800 bits/s and 9 600 bits/s. V.32bis [8] extends the data rates up to 14,400 bits/s. 

5.2.8 Detector cinaracteristics for Recommendation ITU-T T.30 

To activate the Jitter buffer at calling end respectively called end for procedures according to Recommendation 
ITU-T T.30 [i.lO], the tone detector shall detect frequencies described in table 6. 

Table 6: Events for T.30 Signals 



Signal 


Frequency 


CED 

(Called tone which is physically identical to V.25 ANS) 


2 100 Hz 


/CED 
Called tone which is physically identical to V.25 /ANS) 


2 1 00 Hz with phase reversals at an interval of 450 ± 25 ms 


CEDam 
Called tone which is physically identical to V.25 ANSam) 


2 100 Hz amplitude-modulated by a sinewave at 15 Hz 

(Recommendation ITU-T T.30 [i.1 0], clause 4.1 .2; § 6) 

(Recommendation ITU-T V.34 [1.9]) 


/CEDam 
Called tone which is physically identical to V.25 ANSam) 


2 100 Hz amplitude-modulated by a sinewave at 15 Hz with 

phase reversals at an interval of 450 ± 25 ms 

(See note) 


CNG (Calling tone) 


1 100 Hz 


V.21 preamble flag 


(V.21 bits) 


NOTE: Recommendation ITU-T V.34 [i.9] clause 1 1 .1 .2.1 : "Upon connection to line, tlie modem sliail initialiy remain 
silent for a minimum of 200 ms and then transmit signal ANSam according to the procedure In 
Recommendation V.8. If duplex operation is intended, this signal shall include phase reversals as specified 
in Recommendation V.8. If half -duplex operation is intended, phase reversals are optional. The modem shall 
condition its receiver to detect CM and, possibly, calling modem responses from other appropriate 
Recommendations ". 



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Calling terminal Called terminal 

UNO 



CED 




DIS 






DCS 






Training, TCF 






CFR 






Training, FAX MSG 

mjps 


^ 




MCF 




^ 


Training, FAX MSG 
EOP 


p. 


-^ 


MCF 






DCN 


*- 



7108300 1Q-QQ/d1 66 

Figure 8: T.30 procedure 

The detection channel bandwidth should be chosen wide enough to encompass this tones (and possibly other tones used 
within national networks). At the same time, the detection channel bandwidth should be such that, in conjunction with 
guard action and timing, adequate protection is provided against false operation of the detector by speech signals. The 
detector channel sensitivity (threshold level) should be such that the detector will operate on the lowest expected power 
of the tone. 

5.2.9 Noise tolerance 

The detector should operate correctly with white noise less than or equal to 11 dB below the level of the signal which 
should be detected. No definitive guidelines can be given for the range between 5 dB and 11 dB because of the 
variations in the test equipment used. In particular, performance may vary with the peak-to-average ratio of the noise 
generator used. It is noted that it is possible to design a detector capable of operating correctly at 5 dB signal-to-noise 
ratio. 

5.2.10 Operate time 

The operate time should be sufficiently long to provide immunity from false operation due to voice signals, but not so 
long as to needlessly extend the time to disable. The jitter buffer activator is required to operate within one second of 
the receipt of the activating signal. 

5.2.1 1 False operation due to speech signals 

It is desirable that the jitter buffer activator should rarely operate falsely on speech signals. To this end, a reasonable 
objective is that, for an jitter buffer installed on a working circuit, usual speech signals should not on the average cause 
more than 10 false operations during 100 hours of speech. In addition to the talk-off protection supplied by the disabling 
channel bandwidth, by guard band operation and by the operate time, talk-off protection can be supplied by recycling. 
That is, if speech which simulates the signal is interrupted because of inter-syllabic periods, before changing the jitter 
buffer behaviour has taken place, the operate timing mechanism should reset. However, momentary absence or change 
of level in a true signal should not reset the timing. 



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5.2.12 Release time 

For further study. 

5.2.13 Other considerations 

Both the echo of the activating tone and the echo of the calling tone may disturb the detection of the jitter buffer 
enabling tone. As such, it is not recommended to add the receive and transmit signal inputs together to form an input to 
a single detector. 



Activation of jitter buffer for VBD 



During telephony mode, the initiating station sends the calling tone (for fax called CNG, 1 100 Hz, a series of 
interrupted bursts of binary 1 signal or the 1 300 Hz signal (V.25) and while this takes place the user of the receiving 
station may be continuing to speak or send audio. The station on the left (figure 9) is the initiating station. The speech or 
audio signal from the station on the right have placed the jitter buffer in the dynamic state. The following tones shall 
drive both, jitter buffers JB2 and JBl into the fixed mode. 

CED as per Recommendation ITU-T T.30 [i.lO] 

ANS as per Recommendation ITU-T V.8 [1] 

ANSam as per Recommendation ITU-T V.8 [1] 

/ANS am as per Recommendation ITU-T V.8 [1] 

Preamble as per Recommendation ITU-T T.30 [i.lO], section 5.3.1 

2 225 Hz answer tone as per Recommendation ITU-T V. 150. 1 [i. 1 1], appendix VI 

Unscrambled binary 1 is detected for 155 + 50 ms as per Recommendation ITU-T V.22 [5] 

Segment 1 dual tones (1 529 + 2 225) as per Recommendation ITU-T V.8bis [2] 

NOTE: Whereas the operation of JB2 does not constitute a problem, the activation of JB 1 may need special 
attention. This scenario is illustrated in figure 9. 



Speech 



Hybrid 



Hybrid 



JB 1 



JB 



Fax / modem 
station initatiating 



Fax / modem 
answering station 



e.g. CED, ANS, 2225 Hz, CI 



Figure 9: Activation of jitter buffer for VBD inband 



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According to Recommendation ITU-T V.152 [9] the early VBD detection procedure shall be used. In that case the 
following initiating calling tones shall be recognized from the detector which shall drive the jitter buffer JB 1 and JB2 
into the fixed mode: 

CI (V.21 bits) signal V.8 (1 180 Hz, 980 Hz, 1850 Hz, 1 650 Hz) 

CNG, 1 100 Hz, (T.30, V.8) 

CT, 1 300 Hz signal (V.25) 

a series of interrupted bursts of binary 1 signal 

unscrambled binary ones signal as per Recommendation ITU-T V.22 [5] 

initiating Segment 1 dual tones (1 375 Hz and 2 002 Hz) as per Recommendation ITU-T V.8bis [2] 

In the case when the calling tones, needed to activate the early VBD detection, were not detected and the jitter buffers 
were not activated the signals generated from the called side shall be recognized from the detector which shall drive the 
jitter buffers JBl and JB2 into the fixed mode as described in the clause before. 



Speech 



Hybrid 



Hybrid 



JB 1 



JB2 



Fax / modem 
station initatiating 



Fax / modem 
answering station 



e.g. CNG, CT, dual tones 



e.g. CED, ANS, 2225 Hz, CI 



Figure 10: Early VBD detection procedure 



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Signalling without 
tone detection: 

MSANs DO NOT support any 

VBD need early detection 
mechanism. ANS transported 
before both sides in VBD 

mode. 



Signalling with 

tone detection: 

MSANs support any VBD early 

detection mechanism. ANS 

transported when both sides 

already in VBD mode. 



>Unsecure mode before VBD switf^ing - 
higl 



ligher probability of call setup failure 



~^^^^ Secure mode after \'BD switchiinE - 



lower probability of call setup failure 



Figure 1 1 : Signalling with and without VBD early detection 

To minimize the risk of carrier lost, packet loss concealment described in Recommendation ITU-T G.71 1 [i.1 3] 
Appendix I shall be supported. 



7 Activation of jitter buffer for 64 kbit/s bit sequence 
(UDI) 

The fixed jitter buffer from the calling and called side for 64 kbit/s bit sequence (UDI) shall be activated directly by a 
signalization. The activation take place later with the reception of Connect/ ANM (ISUP) or 200 OK (SIP) message. See 
figure 12. 



UDI 



TERMINAL 



TERMINAL 

















JB2 
















JB 1 




^ 















InltatlatIng 



SETUP 



answering station 
CONNECT 



Figure 12: Activation of jitter buffer for VBD activated directly by signalization 



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8 Requirements for values of jitter buffers 



8.1 Fixed jitter buffers 



In case VBD it is the goal to keep the audio end-to-end delay constant during the entire call. The jitter buffer has to be 
implemented in such a way that any jitter occurring during the entire call will not change the end to end delay. 

The jitter buffer may adapt if there is an overflow or under run. 



8.2 Adaptive jitter buffers 



In case of voice the strategy of jitter buffer implementation is to keep the end to end audio delay as low as possible 
under all jitter conditions. Any jitter buffer implementation should mostly not impair the listening speech quality as 
perceived by the user. 

For voice calls between MS AN, IAD, MGW adaptive jitter buffers are required. The minimum jitter buffer size should 
be smaller or equal to one packet size. 

For adaptive jitter buffers the maximum aberration from the real jitter in the network should be one packetization time 
interval. It is recommended that the jitter measurement period for Jitter should be 2 - 3 packet intervals, not only on one 
packet interval. The adaptation interval towards higher values should be done immediately after the jitter measurement 
period. The adaptation towards lower values should be after at least several seconds or during silence periods. 

8.3 Activation procedure into the fixed mode 

The detection of the initiating calling tones should be maximal 200 ms, after that the Jitter Buffer shall adapt the jitter 
buffer rate from the adaptive to the fixed jitter buffer rate. "When the JB adapts to the fixed state, there will be some 
time (JB adaption time) without audio information due to the increasing JB-delay, which will often be replaced with 
supposed audio information by a PLC-algorithm." 

In some cases, the JB adaption time can be critical, especially if this time is higher. In this case the early VBD detection 
procedure should be used. 

Table 7: Examples of jitter buffer adaption time 



Jitter Buffer Adaptive 


Jitter Buffer Fixed 


Jitter buffer adaption time 


20 ms 


100 ms 


40 ms 


20 ms 


200 ms 


90 ms 


40 ms 


100 ms 


30 ms 


40 ms 


200 ms 


80 ms 



8.4 



Transition from VBD to Voice mode (Recommendation 
ITU-T V.1 52) 



Transition from VBD to Voice may be carried out by detection: 

• In the direction from the GSTN to IP network of any of the following stimuli: 

end of modem or facsimile signals; 

voice signals; 

detection in both directions, GSTN to IP and IP to GSTN, of silence. With the following caveats: 

■ For text telephones the appropriate detection of silence shall be considered because text telephone 
conversations may have long periods of silence. 



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■ For the case of facsimile calls the silence period should be greater than the T2 timer defined in 
Recommendation ITU-T T.30 [i.lO]. 

MGC signalling or other out of band signalling method. 

• In the direction from IP to GSTN network due to receipt of RTP packets that have non-VBD payload types 
only after the first VBD RTP packet has been received. This will avoid the situation of an incorrect transition 
into Audio mode when it has transitioned to VBD mode on detection of VBD signals on its TDM side and is 
still receiving Voice RTP packets (because the remote end has not yet transitioned based on reception of the 
VBD RTP packets). 

The above described transition criteria are also summarized in figure 13. 



Detection VBD signals 




Figure 13: Voice-VBD Transitioning state diagram 
(Figure 1 from ITU-T Recommendation V.I 52 [9]) 



8.5 Handling of Jitter Buffer in case of lost or late packets 

As the receiving decoder expects to be fed with voice packets at the same fixed rate, the jitter buffer shall insert dummy 
packets if the packets are lost, or they arrived too late. Depending of the Jitter buffer algorithm, the lost packets will 
often be replaced with supposed audio information by a PLC-algorithm. 



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Voice sample 
irregular arrival pattern 



Voice sample 
leaving, regular playout 



Late packet 



Dummy packet 

-1 

DD 



Voice sample 
leaving, regular playout 



Figure 14: Handling of Jitter Buffer in case of lost or late packets 



9 Echo canceller 

As a general rule, echo cancellers are required in VoIP systems due to the high transmission delay. 

In accordance with Recommendations ITU-T G.131 [i.5] and Q. 115.1 [i.6] echo canceller (EC) according to 
Recommendation ITU-T G.168 [3] shall be used if the mean one way delay of the "talker echo transmission path" 
exceeds the 25 ms limit. 

False detection of tones leading to switch off of an echo canceller during a speech call has to be prevented (similar to 
clause 4.2 for jitter buffer setting). 

9.1 Characteristics of an echo canceller tone disabler 
(Recommendation ITU-T G.168) 

9.1.1 General 

The echo cancellers implemented according Recommendation ITU-T G.168 [3] should be equipped with a tone detector 
that conforms to this clause. This tone detector should disable the echo canceller only upon detection of a signal which 
consists of a 2 100 Hz tone with periodic phase reversals inserted in that tone, and not disable with any other in-band 
signal, e.g. speech or a 2 100 Hz tone without phase reversals. The tone disabler should detect and respond to a 
disabling signal which may be present in either the send or the receive path. 

To improve the operation of the echo canceller for fax signals and low-speed voice band data, it may be beneficial for 
some echo cancellers to disable the NLP for such calls. In this case, the echo canceller may optionally detect any 
2 100 Hz tone without phase reversals. If 2 100 Hz tone without phase reversal is detected, the echo canceller shall 
remain enabled, and the NLP may optionally be disabled. The frequency characteristics of the tone detector are given in 
figure 15. 

The tone disabler characteristics as specified in clauses 7.4 through 7.9 in Recommendation ITU-T G.168 [3] also apply 
for this NLP disabling detector. 

Note that if the 2 100 Hz tone contains phase reversals, then the echo canceller shall be disabled as defined elsewhere in 
this clause. 



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ETSI TS 102 929 V2.1.2 (2013-03) 



The term disabled in this clause refers to a condition in which the echo canceller is configured in such a way as to no 
longer modify the signals which pass through it in either direction. Under this condition, no echo estimate is subtracted 
from the send path, the non-linear processor is made transparent, and the delay through the echo canceller still meets the 
conditions specified in clause 6.4.1.9 in Recommendation ITU-T G.168 [3]. However, no relationship between the 
circuit conditions before and after disabling should be assumed. The impulse response stored in the echo canceller prior 
to convergence (and prior to the disabling tone being sent) is arbitrary. This can lead to apparent additional echo paths 
which, in some echo canceller implementations, remain unchanged until the disabling tone is recognized. Also note that 
echo suppressors could be on the same circuit and there is no specified relationship between their delay in the enabled 
and disabled states. In spite of the above, it is possible, for example, to measure the round-trip delay of a circuit with the 
disabling tone but the trailing edge of the tone burst should be used and sufficient time for all devices to be disabled 
should be allotted before terminating the disabling tone and starting the timing. It should be noted that the echo 
canceller should provide 64 kbit/s bit-sequence integrity when disabled. 

9.1.2 Detector characteristics 

The tone detector shall detect a tone in the frequency range of 2 100 Hz + 21 Hz (see Recommendation 
ITU-T V.21 [4]). 

The detection channel bandwidth should be chosen wide enough to encompass this tone (and possibly other disabling 
tones used within national networks). At the same time, the detection channel bandwidth should be such that, in 
conjunction with guard action and timing, adequate protection is provided against false operation of the detector by 
speech signals. The detector channel sensitivity (threshold level) should be such that the detector will operate on the 
lowest expected power of the disabling tone. The band characteristics shown in figure 12 will permit disabling by the 
2 100 Hz disabling tone as well as others used in North America. The figure indicates that in the frequency band 
2 079 Hz to 2 121 Hz detection shall be possible whilst in the band 1 900 Hz to 2 350 Hz detection may be possible. 

Providing that only the recommended 2 100 Hz disabling tone is used internationally, interference with signalling 
equipment will be avoided. 

The dynamic range of the detector should be consistent with the input levels as specified in Recommendation 
ITU-T V.21 [4] with allowances for variation introduced by the public switched telephone network. 




G.1S3|C5)_I=37 



1900 



:ioo 

:07? 1121 



2350 



Frequency (H?:) 

Figure 15: Required disabling band characteristics 



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ETSI TS 102 929 V2.1.2 (2013-03) 



9.1 .3 Phase reversal detection 

The echo canceller tone disabler requkes the detection of a 2 100 Hz tone with periodic phase reversals which occur 
every 450 + 25 ms. The characteristics of the transmitted signal are defined in Recommendations ITU-T V.25 [6] and 
V.8 [1]. Phase variations in the range of 180° ± 25° should be detected while those in the range of 0° ± 1 10° should not 
be detected. This restriction is to minimize the probability of false disabling of the echo canceller due to speech currents 
and network-induced phase changes. The ±1 10° range represents the approximate phase shift caused by a single frame 
slip in a PCM system. 

9.1 .4 Guard band characteristics 

Energy in the voice band, excluding the disable band, shall be used to oppose disabling so that speech will not falsely 
operate the tone disabler. The guard band should be wide enough and with a sensitivity such that the speech energy 
outside the disabling band is utilized. The sensitivity and shape of the guard band shall not be such that the maximum 
idle or busy circuit noise will prevent disabling. In the requirement, white noise is used to simulate speech and circuit 
noise. Thus, the requirement follows. 

Given that white noise (in a band of approximately 300 Hz to 3 400 Hz) is applied to the tone disabler simultaneously 
with a 2 100 Hz signal, the 2 100 Hz signal is applied at a level 3 dB above the midband disabler threshold level. The 
white noise energy level required to inhibit disabling should be no greater than the level of the 2 100 Hz signal and no 
less than a level 5 dB below the level of the 2 100 Hz signal. As the level of the 2 100 Hz signal is increased over the 
range of levels to 30 dB above the midband disabler threshold level, the white noise energy level required to inhibit 
disabling should always be less than the 2 100 Hz signal level. These requirements, together with the noise tolerance 
requirements given in clause 9.1.5 are illustrated in figure 16. 



SliDuM usA disable 




Should dij^ble 



11 dB 



S.!N 



Q.16S(MlL^3B 



Figure 16: Guard band and noise tolerance requirements 

NOTE: The possibility of interference during the phase reversal detection period has been taken into account. 
One potential source of interference is the presence of calling tone as specified in 
Recommendation ITU-T V.25 [6]. If the calling tone interferes with the detection of the phase reversal, 
the entire disabling detection sequence is restarted, but only one time. Recommendation ITU-T V.25 [6] 
ensures at least one second of quiet time between calling tone bursts. 

9.1.5 Noise tolerance 

The detector should operate correctly with white noise less than or equal to 1 1 dB below the level of the 2 100 Hz 
signal. No definitive guidelines can be given for the range between 5 dB and 1 1 dB because of the variations in the test 
equipment used. In particular, performance may vary with the peak-to-average ratio of the noise generator used. As a 
general guideline, however, the percentage of correct operation (detection of phase variations of 180° ± 25° and 
non-detection of phase variations of 0° + 1 10°) should fall by no more than 1 % for each dB reduction in the 
signal-to-noise ratio below 1 1 dB. It is noted that it is possible to design a detector capable of operating correctly at 
5 dB signal-to-noise ratio. 



ETSI 



27 ETSI TS 1 02 929 V2.1 .2 (201 3-03) 



9.1 .6 Holding-band characteristics 



The tone detector, after disabling either the NLP or the echo canceller, should hold the NLP or echo canceller in the 
disabled state for tones in a range of frequencies specified below. The release sensitivity should be sufficient to 
maintain disabling for the lowest level data signals expected, but should be such that the detector will release for the 
maximum idle or busy circuit noise. Thus the requirement follows: 

• The tone detector should hold the NLP or echo canceller in the disabled state for any single-frequency sinusoid 
in the band from 390 Hz to 700 Hz having a level of -27 dBmO or greater, and from 700 Hz to 3 000 Hz 
having a level of -31 dBmO or greater. The tone disabler should release for any signal in the band from 200 Hz 
to 3 400 Hz having a level of -36 dBmO or less. 

NOTE: If this function is not implemented (as in many gateways to date), it can lead to situations, where the echo 
canceller is switched off, even if it should be switched on again. This can be the case in the following 
situation: V.17 Fax calls V.34 Fax > Answer tone will be for V.34 (> EC off), connection will be V.17 
(EC should be on). 

9.1.7 Operate time 

The operate time should be sufficiently long to provide immunity from false operation due to voice signals, but not so 
long as to needlessly extend the time to disable. The tone disabler is required to operate within one second of the receipt 
of the disabling signal. The one second operate time permits the detection of the 2 100 Hz tone and ensures that 
two-phase reversals will occur. 

9.1 .8 False operation due to speech currents 

It is desirable that the tone disabler should rarely operate falsely on speech. To this end, a reasonable objective is that, 
for an echo canceller installed on a working circuit, usual speech currents should not on the average cause more than 10 
false operations during 100 hours of speech. 

In addition to the talk-off protection supplied by the disabling channel bandwidth, by guard band operation and by the 
operate time, talk-off protection can be supplied by recycling. That is, if speech which simulates the disabling signal is 
interrupted because of inter-syllabic periods, before disabling has taken place, the operate timing mechanism should 
reset. However, momentary absence or change of level in a true disabling signal should not reset the timing. 

9.1 .9 False operation due to data signals 

It is desirable that the tone disabler should rarely operate falsely on data signals from data sets that would be adversely 
affected by disabling the echo canceller. To this end, a reasonable objective is that, for an echo canceller installed on a 
working circuit, usual data signals from such data sets should not, on the average, cause more than 10 false operations 
during 100 hours of data transmissions. 

To this end, in the reference tone disabler described in annex B of Recommendation ITU-T G.165 [i.2], which meets the 
above requirements, the tone disabler circuitry becomes inoperative if one second of clear (i.e. no phase reversals or 
other interference) 2 100 Hz tone is detected. The detector circuit remains inoperative during the data transmission and 
only becomes operative again 250 ± 150 ms after a signal in the holding band falls at least 3 dB below the maximum 
holding sensitivity. Thus the possibility of inadvertent disabling of the echo canceller during facsimile or low speed 
(< 9,6 kbit/s) voice band data transmission is minimized. 

9.1.10 Release time 

The disabler should not release for signal drop-outs less than the ITU-T recommended value of 100 ms. To cause a 
minimum of impairment upon accidental speech disabling, it should release within 250 ms ± 150 ms after a signal in the 
holding band falls at least 3 dB below the maximum holding sensitivity in both directions of signal transmission. 

9.1.11 Other considerations 

Both the echo of the disabling tone and the echo of the calling tone may disturb the detection of the echo canceller 
disabling tone. As such, it is not recommended to add the receive and transmit signal inputs together to form an input to 
a single detector. 



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28 ETSI TS 1 02 929 V2.1 .2 (201 3-03) 

Careful attention should be given to the number of phase reversals required for detection of the disabling tone. Some 
Administrations favour relying on 1 to improve the probability of detection even in the presence of slips, impulse noise, 
and low signal-to-noise ratio. Other Administrations favour relying on 2 to improve the probability of correctly 
distinguishing between non-phase-reversed and phase-reversed 2 100 Hz tones, and to reduce the likelihood of false 
triggering of the tone disabler by speech or data signals. 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Annex A (normative): 
Jitter buffer Facsimile tests 



These tests should ensure that the Jitter Buffer located at each end of a connection converge rapidly on the initial 
handshaking sequences of a facsimile call. The test and requirements were originally developed to overcome problems 
in the network due to the turnaround of fax and modem handshaking signals. 



A.1 IVIeasurement method 



The test method is based on the analysis of measurement of delay over time of the device under test. Artificial 
introduced jitter can be used to help with this analysis. 



▼ t 



Delay Analysis 
Drei and Djg; 



iL U 




level 

SsNDREF 



Test 

signal 
with level 
Rev 






Figure A.1 : Test configuration A calls B 



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30 



ETSI TS 102 929 V2.1.2 (2013-03) 



▼ t 



Delay Analysis 
DjBi and Djb2 



iL ik 






Figure A.2: Test configuration B calls A 

Aq - output level interface A 

Ain - input level interface A 

Bin" input level interface B 

Bo - output level interface B 

Doout - sending delay interface A (coder delay, see table 22 of [1]) 

DjBi - jitter buffer delay interface B 

Diij, - receiving delay interface B (Decompression time per block + Serialization time + PLC) 

Diou, - sending delay interface B (coder delay, see table 22 of [1]) 

DjB2 - jitter buffer delay interface A 

Doin - receiving delay interface B (Decompression time per block + Serialization time + PLC) 

NOTE: Decoder delay = D„+Djb 

Used signals 

C16 Signal of Test 2A (Recommendation ITU-T G.168 [3]), average level -16 dBmO Gaussian white 

noise signal which is used to identify the echo-path impulse response. 

D16 Signal consisting of DTMF tones 0123456789#ABCD* with signal-to-pause relationship 

corresponding to that of CI 6, average level -16 dBmO. 

ANS 2 100 Hz sine (Recommendation ITU-T V.25 [6]) The duration of the tone is set to Tl = 1,35 s. 

ANSam 2 100 Hz sine with a 20 % amplitude modulation by a 15 Hz sine (Recommendation 

ITU-T V.25 [6]). 

/ANS 2 100 Hz sine with 180° phase shift every 450 ms (Recommendation ITU-T V.25 [6]). 



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ETSI TS 102 929 V2.1.2 (2013-03) 



/ANSam 2 100 Hz sine with a 20 % amplitude modulation by a 15 Hz sine and 180° phase shift every 

450 ms (Recommendation ITU-T V.25 [6]). 

CI CI sequence consists of 10 ONEs followed by 10 synchronization bits and the call function octet. 

For the transmission are used 980 Hz for '1' (mark) and 1 180 Hz for '0' (space) (low channel uses) 
and the frequencies 1 650 Hz for '1' and 1 850 Hz for '0' (high channel uses). 

CT 1 300 Hz sine CT (calling tone) consists of a series of interrupted bursts of 1 300-Hz tone, on for a 

duration of not less than 0,5 s and not more than 0,7 s and off for a duration of not less than 1,5 s 
and not more than 2,0 s. 

CNG 1 100 Hz sine Duration On for 0,5 s to 0,7 s. Off 1,8 s to 2,5 (Recommendation ITU-T V.25 [6]). 

FAX Sequence No. 1 (Recommendation ITU-T G.168 [3], clause 6.4.2.11). 



Test number: 


1.1.1.1 FAX 


Transmission Type: 


Facsimile with ANS /-1 2 dBmO 


IVIeasurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter 

• Buffer 2 Apply signal ANS to Interface B 

• Apply signal CI 6 to Interface A and determine the delay Djeiafter sending ANS 
(from B) 

• Apply signal C16 to Interface B and determine level Ssnd and Rev and the delay 
DjB2 after sending ANS (from B) 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C16 to Interface B and determine the delay Djb2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal ANS to Interface A 

• Apply signal C16 to Interface B and determine the delay Djbi after sending ANS 
(from A) 

• Apply signal C1 6 to Interface A and determine the delay Djb2 after sending ANS 
(from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 Delay for Jitter Buffer Fixed 


FAX test sequences: 

Calling tone (CNG) 

Conditions 




Called station identification 

(CED) 

Conditions 


CED (ANS) 2 100 Hz ± 15 Hz sine (Recommendation ITU-T V.25 [6]) 

Duration 3 s 

(G.168 clause 6.4.2.1 1 Test No. 10 - Facsimile test) 

The amplitude of the tone is -12 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


1.1.1.2 FAX 


Transmission Type: 


Facsimile with ANS /-35 dBmO 


Measurement procedure 


A) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface A and determine the delay D Djbi 

• Apply signal 016 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter 

• Buffer 2 

• Apply signal ANS to Interface B 

• Apply signal 01 6 to Interface A and determine the delay Djbi after sending ANS 
(from B) 

• Apply signal 01 6 to Interface B and determine the delay Djb2 after sending ANS 
(from B) 

B) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 016 to Interface B and determine the delay Djb2 

• Apply signal 01 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal ANS to Interface A 

• Apply signal 016 to Interface B and determine the delay Djbi after sending ANS 
(from A) 

• Apply signal 01 6 to Interface A and determine the delay Djb2 after sending ANS 
(from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


FAX test sequences: 

Calling tone (CNG) 

Conditions 




Called station 

identification (CED) 

Conditions 


OED (ANS) 2 100 Hz ± 15 Hz sine (Recommendation ITU-T V.25 [6]) 

Duration 3 s 

(G. 1 68 clause 6.4.2. 1 1 Test No. 1 - Facsimile test) 

The amplitude of the tone is -35 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


1.1.2.1 FAX 


Transmission Type: 


Facsimile with early VBD detection with CNG / -12 dBmO 


Measurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 01 6 to Interface A and determine the delay Djbi 

• Apply signal 016 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal ONG to Interface A 

• Apply signal 016 to Interface A and determine the delay Djeiafter sending ONG 
from A 

• Apply signal 01 6 to Interface B and determine the delay Djb2 after sending ONG 
from A 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 016 to Interface B and determine the delay Djb2 

• Apply signal 01 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal ONG to Interface B 

• Apply signal 016 to Interface B and determine the delay Djbi after sending ONG 
from B 

• Apply signal 01 6 to Interface A and determine the delay Djb2 after sending ONG 
from B 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


FAX test sequences: 

Calling tone (CNG) 

Conditions 




Called station 

identification (CED) 

Conditions 


OED (ANS) 2 1 00 Hz ± 1 5 Hz sine (Recommendation ITU-T V.25 [6]) 

Duration 3 s 

(G. 1 68 clause 6.4.2. 1 1 Test No. 1 - Facsimile test) 

The amplitude of the tone is -12 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


1.1 .2.2 FAX 


Transmission Type: 


Facsimile with early VBD detection with CNG / -35 dBmO 


Measurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 01 6 to Interface A and determine the delay Djbi 

• Apply signal 016 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal ONG to Interface A 

• Apply signal 016 to Interface A and determine the delay Djeiafter sending ONG 
from A 

• Apply signal 01 6 to Interface B and determine the delay Djb2 after sending ONG 
from A 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 016 to Interface B and determine the delay Djb2 

• Apply signal 01 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal ONG to Interface B 

• Apply signal 016 to Interface B and determine the delay Djbi after sending ONG 
from B 

• Apply signal 01 6 to Interface A and determine the delay Djb2 after sending ONG 
from B 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second Call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay jitter for Voice 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


FAX test sequences: 

Calling tone (CNG) 

Conditions 




Called station 

identification (CED) 

Conditions 


OED (ANS) 2 1 00 Hz ± 1 5 Hz sine (Recommendation ITU-T V.25 [6]) 

Duration 3 s 

(G. 1 68 clause 6.4.2. 1 1 Test No. 1 - Facsimile test) 

The amplitude of the tone is -35 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


1.1.3.1 FAX 


Transmission Type: 


Facsimile witli V.1 7 data transmission with ANS / -12 dBmO 


IVIeasurement procedure 


1) 

• Establisliing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CNG to Interface A 

• Apply signal ANS to Interface B 

• Apply transmission of FAX 

• Apply signal C1 6 to Interface A and determine the delay DjBiafter transmission of 
FAX 

• Apply signal C1 6 to Interface B and determine the delay Djb2 after sending FAX 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CNG to Interface B 

• Apply signal ANS to Interface A 

• Apply transmission of FAX 

• Apply signal C1 6 to Interface B and determine the delay Djbi after transmission of 
FAX from B 

• Apply signal C1 6 to Interface A and determine the delay Djb2 after transmission of 
FAX 

• The transmission of the signal CI 6 shall be without time interruption after the 
transmission of the FAX transmission 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay jitter for Voice 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


FAX test sequences: 

Calling tone (CNG) 

Conditions 




Called station 

identification (CED) 

Conditions 


CED (ANS) 2 100 Hz ± 15 Hz sine (Recommendation ITU-T V.25 [6]) 

Duration 3 s 

(G.168 clause 6.4.2.11 Test No. 1 - Facsimile test) 

The amplitude of the tone is -12 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


1.1 .3.2 FAX 


Transmission Type: 


Facsimile with V.17 data transmission witli ANS / -35 dBmO 


IVIeasurement procedure 


1) 

• Establisliing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CNG to Interface A 

• Apply signal ANS to Interface B 

• Apply transmission of FAX 

• Apply signal C1 6 to Interface A and determine the delay DjBiafter transmission of 
FAX 

• Apply signal C1 6 to Interface B and determine the delay Djb2 after sending FAX 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CNG to Interface B 

• Apply signal ANS to Interface A 

• Apply transmission of FAX 

• Apply signal C1 6 to Interface B and determine the delay Djbi after transmission of 
FAX from B 

• Apply signal C1 6 to Interface A and determine the delay Djb2 after transmission of 
FAX 

• The transmission of the signal CI 6 shall be without time interruption after the 
transmission of the FAX transmission 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay jitter for Voice 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


FAX test sequences: 

Calling tone (CNG) 

Conditions 




Called station 

identification (CED) 

Conditions 


CED (ANS) 2 100 Hz ± 15 Hz sine (Recommendation ITU-T V.25 [6]) 

Duration 3 s 

(G.168 clause 6.4.2.11 Test No. 1 - Facsimile test) 

The amplitude of the tone is -35 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


1.1.4.1 FAX 


Transmission Type: 


Facsimile with /ANS / -1 2 dBmO 


Measurement procedure 


1) 

• Establisliing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANS to Interface B 

• Apply signal C1 6 to Interface A and determine the delay Djeiafter sending /ANS 
(from B) 

• Apply signal C1 6 to Interface B and determine the delay Djb2 after sending /ANS 
(from B) 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANS to Interface A 

• Apply signal C1 6 to Interface B and determine the delay Djbi after sending /ANS 
(from A) 

• Apply signal C1 6 to Interface A and determine the delay Djb2 after sending ANS 
(from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) DjBi = DjB2 for Delay for Jitter Buffer Fixed) 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


FAX test sequences: 

Calling tone (CNG) 

Conditions 




Called station 

identification (CED) 

Conditions 


/ANS -2 100 Hz ±15 Hz sine (Recommendation ITU-T V.25 [6]) with 180 "phase shift 

every 450 ms 

(Recommendation ITU-T V.25 [6]) 

Duration 3 s 

The amplitude of the tone is -12 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


1.1.4.2 FAX 


Transmission Type: 


Facsimile with /ANS / -35 dBmO 


IVIeasurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANS to Interface B 

• Apply signal CI 6 to Interface A and determine the delay DjBiafter sending /ANS 
(from B) 

• Apply signal CI 6 to Interface B and determine the delay Djb2 after sending /ANS 
(from B) 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANS to Interface A 

• Apply signal CI 6 to Interface B and determine the delay Djbi after sending /ANS 
(from A) 

• Apply signal CI 6 to Interface A and determine the delay Djb2 after sending ANS 
(from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


FAX test sequences: 

Calling tone (CNG) 

Conditions 




Called station identification 

(CED) 

Conditions 


/ANS 2 100 Hz ± 15 Hz sine (Recommendation ITU-T V.25 [6]) with 180° phase shift 

every 450 ms 

(Recommendation ITU-T V.25 [6]) 

Duration 3 s 

The amplitude of the tone is -35 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


1.1.5.1 FAX 


Transmission Type: 


Facsimile witli V.34 data transmission with /ANS / -12 dBmO 


Measurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Apply signal /ANS to Interface B 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply transmission of FAX 

• Apply signal CI 6 to Interface A and determine the delay DjBiafter sending FAX 
from interface A 

• Apply signal CI 6 to Interface B and determine the delay Djb2 after sending FAX 
from interface A 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANS to Interface A 

• Apply transmission of FAX 

• Apply signal CI 6 to Interface B and determine the delay Djbi after sending FAX 
from B 

• Apply signal CI 6 to Interface A and determine the delay Djb2 after sending FAX 
from B 


Requirement 


1) 

a) First call;DjBi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


FAX test sequences: 

Calling tone (CNG) 

Conditions 




Called station identification 

(CED) 

Conditions 


/ANS 2 100 Hz ±15 Hz sine (Recommendation ITU-T V.25 [6]) with 180° phase shift 

every 450 ms 

(Recommendation ITU-T V.25 [6]) 

Duration 3 s 

The amplitude of the tone is -12 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


1.1.5.2 FAX 


Transmission Type: 


Facsimile witli V.34 data transmission with /ANS / -35 dBmO 


Measurement procedure 


1) 

• Establisliing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Apply signal /ANS to Interface B 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply transmission of FAX 

• Apply signal CI 6 to Interface A and determine the delay DjBiafter sending FAX 
from interface A 

• Apply signal CI 6 to Interface B and determine the delay Djb2 after sending FAX 
from interface A 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANS to Interface A 

• Apply transmission of FAX 

• Apply signal CI 6 to Interface B and determine the delay Djbi after sending FAX 
from B 

• Apply signal CI 6 to Interface A and determine the delay Djb2 after sending FAX 
from B 


Requirement 


1) 

a) First call;DjBi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


FAX test sequences: 

Calling tone (CNG) 

Conditions 




Called station identification 

(CED) 

Conditions 


/ANS 2 100 Hz ±15 Hz sine (Recommendation ITU-T V.25 [6]) with 180° phase shift 

every 450 ms 

(Recommendation ITU-T V.25 [6]) 

Duration 3 s 

The amplitude of the tone is -35 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


1.1.6.1 FAX 


Transmission Type: 


Facsimile witli /ANSam / -12 dBmO 


IVIeasurement procedure 


1) 

• Establisliing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANSam to Interface B 

• Apply signal C1 6 to Interface A and determine the delay Djeiafter sending 
/ANSam (from B) 

• Apply signal C1 6 to Interface B and determine the delay Djb2 after sending 
/ANSam (from B) 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANSam to Interface A 

• Apply signal C1 6 to Interface B and determine the delay Djbi after sending 
/ANSam (from A) 

• Apply signal C1 6 to Interface A and determine the delay Djb2 after sending 
/ANSam (from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


FAX test sequences: 

Calling tone (CNG) 

Conditions 




Called station 

identification (CED) 

Conditions 


/ANSam - 2 1 00 Hz ± 1 5 Hz sine (Recommendation ITU-T V.25 [6]) 2 1 00 Hz amplitude- 
modulated by a sinewave at 15 Hz with phase reversals at an interval of 450 + 25 ms 
Duration 3 s 
The amplitude of the tone is -12 dBmO 



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42 



ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


1.1.6.2 FAX 


Transmission Type: 


Facsimile witli /ANSam / -35 dBmO 


Measurement procedure 


1) 

• Establisliing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANSam to Interface B 

• Apply signal C1 6 to Interface A and determine the delay Djeiafter sending 
/ANSam (from B) 

• Apply signal C1 6 to Interface B and determine the delay Djb2 after sending 
/ANSam (from B) 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANSam to Interface A 

• Apply signal C1 6 to Interface B and determine the delay Djbi after sending 
/ANSam (from A) 

• Apply signal C1 6 to Interface A and determine the delay Djb2 after sending 
/ANSam (from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


FAX test sequences: 

Calling tone (CNG) 

Conditions 




Called station identification 

(CED) 

Conditions 


/ANSam 2 100 Hz ± 15 Hz sine (Recommendation ITU-T V.25 [6]) 2 100 Hz amplitude- 
modulated by a sinewave at 15 Hz with phase reversals at an interval of 450 + 25 ms 
Duration 3 s 
The amplitude of the tone is -35 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


1.1.7.1 FAX 


Transmission Type: 


Facsimile with V.34 data transmission with /ANSam / -12 clBmO 


Measurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANSam to Interface B 

• Apply transmission of FAX 

• Apply signal CI 6 to Interface A and determine the delay DjBiafter sending 
/ANSam (from B) + fax transmission 

• Apply signal CI 6 to Interface B and determine the delay Djb2 after sending 
/ANSam (from B) + fax transmission 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANSam to Interface A 

• Apply transmission of FAX 

• Apply signal CI 6 to Interface B and determine the delay Djbi after sending fax 
transmission 

• Apply signal CI 6 to Interface A and determine the delay Djb2 after fax 
transmission 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


FAX test sequences: 

Calling tone (CNG) 

Conditions 




Called station identification 

(CED) 

Conditions 


/ANSam 2 100 Hz ± 15 Hz sine (Recommendation ITU-T V.25 [6]) 2 100 Hz amplitude- 
modulated by a sinewave at 15 Hz with phase reversals at an interval of 450 + 25 ms 
Duration 3 s 
The amplitude of the tone is -12 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


1.1.7.2 FAX 


Transmission Type: 


Facsimile with V.34 data transmission with /ANSam / -35 clBmO 


Measurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANSam to Interface B 

• Apply transmission of FAX 

• Apply signal CI 6 to Interface A and determine the delay DjBiafter sending 
/ANSam (from B) + fax transmission 

• Apply signal CI 6 to Interface B and determine the delay Djb2 after sending 
/ANSam (from B) + fax transmission 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANSam to Interface A 

• Apply transmission of FAX 

• Apply signal CI 6 to Interface B and determine the delay Djbi after sending fax 
transmission 

• Apply signal CI 6 to Interface A and determine the delay Djb2 after fax 
transmission 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


FAX test sequences: 

Calling tone (CNG) 

Conditions 




Called station identification 

(CED) 

Conditions 


/ANSam 2 100 Hz ± 15 Hz sine (Recommendation ITU-T V.25 [6]) 2 100 Hz amplitude- 
modulated by a sinewave at 15 Hz with phase reversals at an interval of 450 + 25 ms 
Duration 3 s 
The amplitude of the tone is -35 dBmO 



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45 



ETSI TS 102 929 V2.1.2 (2013-03) 



Jitter buffer Modem tests 



Test number: 


2.1.1 MODEM 


Transmission Type: 


Modem with ANS / -1 2 dBmO 


Measurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Apply signal 016 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal ANS to Interface B 

• Apply signal 016 to Interface A and determine the delay DjBiafter sending ANS 
(from B) 

• Apply signal 01 6 to Interface B and determine the delay Djb2 after sending ANS 
(from B) 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 01 6 to Interface B and determine the delay Djb2 

• Apply signal 01 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal ANS to Interface A 

• Apply signal 01 6 to Interface B and determine the delay Djbi after sending ANS 
(from A) 

• Apply signal 01 6 to Interface A and determine the delay Djb2 after sending ANS 
(from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call;DjBi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


IVIodem test sequences: 
Calling tone 
Conditions 




Called station identification 
Conditions 


ANS 2 1 00 Hz ± 1 5 Hz sine (Recommendation ITU-T V.25 [6]) 
Duration 2,6 s to 4 s 

(G.168 [3], clause 6.4.2.11 Test No. 10 - Facsimile test) 
The amplitude of the tone is -12 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


2.1.2 MODEM 


Transmission Type: 


Modem with early VBD detection with CT/ -12 dBmO 


IVIeasurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CT, 1 300 Hz signal (V.25) to Interface A 

• Apply signal C1 6 to Interface A and determine the delay Djeiafter CT, 1 300 Hz 
signal (V.25) to Interface A 

• Apply signal C1 6 to Interface B and determine the delay Djb2 after sending CT, 
1 300 Hz signal (V.25) to Interface A 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CT, 1 300 Hz signal (V.25) to Interface B 

• Apply signal C1 6 to Interface B and determine the delay Djbi after sending ANS 
(from A) 

• Apply signal C1 6 to Interface A and determine the delay Djb2 after sending ANS 
(from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call;DjBi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


Modem test sequences: 
Calling tone 
Conditions 


Signal 1 300 Hz 

Duration On for 0,5 s to 0,7 s, Off for 1 ,5 s to 2 s 

The amplitude of the tone is -12 dBmO 


Called station identification 
Conditions 





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47 



ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


2.1 .3 MODEM 


Transmission Type: 


Modem with early VBD detection with CT / - 35 dBmO 


IVIeasurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CT, 1 300 Hz signal (V.25) to Interface A 

• Apply signal CI 6 to Interface A and determine the delay DjBiafter CT, 1 300 Hz 
signal (V.25) to Interface A 

• Apply signal CI 6 to Interface B and determine the delay Djb2 after sending CT, 
1 300 Hz signal (V.25) to Interface A 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface B and determine the delay Djb2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CT, 1 300 Hz signal (V.25) to Interface B 

• Apply signal C1 6 to Interface B and determine the delay Djbi after sending ANS 
(from A) 

• Apply signal C1 6 to Interface A and determine the delay Djb2 after sending ANS 
(from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call;DjBi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 Jitter Buffer Fixed 


Modem test sequences: 
Calling tone 
Conditions 


Signal 1 300 Hz 

Duration On for 0,5 s to 0,7 s. Off for 1 ,5 s to 2 s 

The amplitude of the tone is - 35 dBmO 


Called station identification 
Conditions 





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48 



ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


2.2.1 MODEM 


Transmission Type: 


Modem with ANSam / -12 dBmO 


IVIeasurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal C1 6 to Interface A and determine the delay Djbi 

• Apply signal C16 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal ANSam to Interface B 

• Apply signal CI 6 to Interface A and determine the delay DjBiafter sending 
ANSam (from B) 

• Apply signal 01 6 to Interface B and determine the delay Djb2 after sending 
ANSam (from B) 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 016 to Interface B and determine the delay Djb2 

• Apply signal 01 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal ANSam to Interface A 

• Apply signal 016 to Interface B and determine the delay Djbi after sending 
ANSam (from A) 

• Apply signal 01 6 to Interface A and determine the delay Djb2 after sending 
ANSam (from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


Modem test sequences: 
Calling tone 
Conditions 




Called station identification 
Conditions 


ANSam 2 100 Hz sine with a 20 % amplitude modulation by a 15 Hz sine 
(Recommendation ITU-T V.25 [6]) 
The amplitude of the tone is -12 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


2.2.2 MODEM 


Transmission Type: 


Modem with ANSam / - 35 dBmO 


IVIeasurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal ANSam to Interface B 

• Apply signal CI 6 to Interface A and determine the delay DjBiafter sending 
ANSam (from B) 

• Apply signal CI 6 to Interface B and determine the delay Djb2 after sending 
ANSam (from B) 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal ANSam to Interface A 

• Apply signal CI 6 to Interface B and determine the delay Djbi after sending 
ANSam (from A) 

• Apply signal CI 6 to Interface A and determine the delay Djb2 after sending 
ANSam (from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


Modem test sequences: 
Calling tone 
Conditions 




Called station identification 
Conditions 


ANSam 2 100 Hz sine with a 20 % amplitude modulation by a 15 Hz sine 
Recommendation ITU-T V.25 [6] 

The amplitude of the tone is - 35 dBmO 



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50 



ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


2.3.1 MODEM 


Transmission Type: 


Modem with early VBD detection with CI Signal {V.8) / -12 dBmO 


Measurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 01 6 to Interface A and determine the delay Djbi 

• Apply signal 016 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 01 Signal (V.8) to Interface A 

• Apply signal 016 to Interface A and determine the delay DjBiafter sending 01 
Signal (V.S) to Interface A 

• Apply signal 01 6 to Interface B and determine the delay Djb2 after sending 01 
Signal (V.S) to Interface A 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 016 to Interface B and determine the delay Djb2 

• Apply signal 01 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 01 Signal (V.8) to Interface B 

• Apply signal 016 to Interface B and determine the delay Djbi after sending 01 
Signal (V.8) to Interface B 

• Apply signal 01 6 to Interface A and determine the delay Djb2 after sending 01 
Signal (V.S) to Interface B 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call;DjBi = Djb2 for Delay Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


IVIodem test sequences: 
Calling tone 
Conditions 


01 Signal (V.S) 

The amplitude of the tone is -12 dBmO 


Called station identification 
Conditions 





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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


2.3.2 MODEM 


Transmission Type: 


Modem with early VBD detection with CI Signal (V.8) / - 35 dBmO 


Measurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 01 6 to Interface A and determine the delay Djbi 

• Apply signal 016 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 01 Signal (V.8) to Interface A 

• Apply signal 016 to Interface A and determine the delay DjBiafter sending 01 
Signal (V.S) to Interface A 

• Apply signal 01 6 to Interface B and determine the delay Djb2 after sending 01 
Signal (V.S) to Interface A 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 016 to Interface B and determine the delay Djb2 

• Apply signal 01 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal 01 Signal (V.8) to Interface B 

• Apply signal 016 to Interface B and determine the delay Djbi after sending 01 
Signal (V.S) to Interface B 

• Apply signal 01 6 to Interface A and determine the delay Djb2 after sending 01 
Signal (V.S) to Interface B 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


Modem test sequences: 
Calling tone 
Conditions 


01 Signal (V.S) 

The amplitude of the tone is - 35 dBmO 


Called station identification 
Conditions 





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52 



ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


2.4.1 MODEM 


Transmission Type: 


Modem with /ANS / - 1 2 dBmO 


IVIeasurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANS to Interface B 

• Apply signal CI 6 to Interface A and determine the delay DjBiafter sending /ANS 
(from B) 

• Apply signal CI 6 to Interface B and determine the delay Djb2 after sending /ANS 
(from B) 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANS to Interface A 

• Apply signal CI 6 to Interface B and determine the delay Djbi after sending 
/ANS(from A) 

• Apply signal CI 6 to Interface A and determine the delay Djb2 after sending 
/ANS(from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call;DjBi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


Modem test sequences: 
Calling tone 
Conditions 




Called station identification 
Conditions 


/ANS 2 100 Hz sine with 180° phase shift every 450 ms (Recommendation ITU-T V.25 

[6]) 

Duration 2,6 s to 4 s 

The amplitude of the tone is -12 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


2.4.2 MODEM 


Transmission Type: 


Modem with /ANS / - 35 dBmO 


IVIeasurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANS to Interface B 

• Apply signal CI 6 to Interface A and determine the delay DjBiafter sending /ANS 
(from B) 

• Apply signal CI 6 to Interface B and determine the delay Djb2 after sending /ANS 
(from B) 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANS to Interface A 

• Apply signal CI 6 to Interface B and determine the delay Djbi after sending 
/ANS(from A) 

• Apply signal CI 6 to Interface A and determine the delay Djb2 after sending 
/ANS(from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call;DjBi = Djb2 Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay Jitter Buffer Fixed 


Modem test sequences: 
Calling tone 
Conditions 




Called station identification 
Conditions 


/ANS 2 1 00 Hz sine with 1 80 ° phase shift every 450 ms (Recommendation ITU-T V.25 

[6]) 

Duration 2,6 s to 4 s 

The amplitude of the tone is - 35 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


2.5.1 MODEM 


Transmission Type: 


Modem with /ANSam / - 1 2 dBmO 


Measurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANSam to Interface B 

• Apply signal CI 6 to Interface A and determine the delay DjBiafter sending 
/ANSam (from B) 

• Apply signal CI 6 to Interface B and determine the delay Djb2 after sending 
/ANSam (from B) 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANSam to Interface A 

• Apply signal CI 6 to Interface B and determine the delay Djbi after sending 
/ANSam(from A) 

• Apply signal CI 6 to Interface A and determine the delay Djb2 after sending 
/ANSam (from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


Modem test sequences: 
Calling tone 
Conditions 




Called station identification 
Conditions 


/ANSam 2 100 Hz sine with a 20 % amplitude modulation by a 15 Hz sine and 180° 
phase shift every 450 ms (Recommendation ITU-T V.25 [6]) 
The amplitude of the tone is -12 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Test number: 


2.5.2 MODEM 


Transmission Type: 


Modem with /ANSam / - 35 dBmO 


Measurement procedure 


1) 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Establishing a new call from A to B and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANSam to Interface B 

• Apply signal CI 6 to Interface A and determine the delay DjBiafter sending 
/ANSam (from B) 

• Apply signal CI 6 to Interface B and determine the delay Djb2 after sending 
/ANSam (from B) 

II) 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal CI 6 to Interface B and determine the delay Djb2 

• Apply signal CI 6 to Interface A and determine the delay Djbi 

• Establishing a new call from B to A and reset Jitter Buffer 1 and Jitter Buffer 2 

• Apply signal /ANSam to Interface A 

• Apply signal CI 6 to Interface B and determine the delay Djbi after sending 
/ANSam(from A) 

• Apply signal CI 6 to Interface A and determine the delay Djb2 after sending 
/ANSam (from A) 


Requirement 


1) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 

II) 

a) First call; Djbi = Djb2 Delay for Jitter Buffer Adaptive 

b) Second call; Djbi = Djb2 for Delay for Jitter Buffer Fixed 


Modem test sequences: 
Calling tone 
Conditions 




Called station identification 
Conditions 


/ANSam 2 100 Hz sine with a 20 % amplitude modulation by a 15 Hz sine and 180° 

phase shift every 450 ms [5]) 

The amplitude of the tone is - 35 dBmO 



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ETSI TS 102 929 V2.1.2 (2013-03) 



Annex B (normative): 
Echo canceller Tests 

B.1 Introduction 

The following tests contains Echo canceller Tests based on disabling characteristics described in 
Recommendations ITU-T G.168 [3] and G.164 [i.l]. 



B.1.1 Signals used 



C16 Signal of Test 2A (Recommendation ITU-T G.168 [3]), average level -16 dBmO Gaussian white 

noise signal which is used to identify the echo-path impulse response 

D16 Signal consisting of DTMF tones 0123456789#ABCD* with signal-to-pause relationship 

corresponding to that of CI6, average level -16 dBmO 

ANS 2 100 Hz sine (Recommendation ITU-T V.25 [6]) The duration of the tone is set to Tl = 1,35 s. 

The amplitude of the tone is -12 dBmO 

ANSam 2 100 Hz sine with a 20 % amplitude modulation by a 15 Hz sine 

(Recommendation ITU-T V.25 [6]) 

/ANS 2 100 Hz sine with 180° phase shift every 450 ms (Recommendation ITU-T V.25 [6]) 

/ANSam 2 100 Hz sine with a 20 % amplitude modulation by a 15 Hz sine and 180° phase shift every 

450 ms (Recommendation ITU-T V.25 [6]) 

FAX Sequence No. 1 (Recommendation ITU-T G.168 [3], clause 6.4.2.11) 



B.1.2 Preparatory measurements 

The JRLsND and JLRrcv are to be determined according to figure B.l. 




Figure B.1 : Echo simulation for determination of JRLsnd and JLRrcv 

As a test signal, the artificial voice should be used. 



ETSI 



57 



ETSI TS 102 929 V2.1.2 (2013-03) 



The possible attenuations/amplifications Ain, Aout, Bin and Bout are to be determined and used for compensation in the 
later measurements. 



B.2 Tests with echo simulation at Interface B 

The measurement setup is shown in figure B.2. 




Figure B.2: Measurement setup for echo simulation 

The levels marked as S and S - ERLsnd shall match at the respective points of the network. 

ERLsND is to be set to 8 dB. Because network echo cancellers are tested in G.168 with ERL of 6 dB, even a small 
maladjustment of the levels in the complete system can lead into the situation that the EC does not consider the echo as 
but as near end speech. Therefore a safety margin of 2 dB is built in. 

ERLEsndref= Transmitted signal at interface A 

ERLEsnd= Received signal measured at interface A 

Ao, Ain = Input and output attenuation Interface A (shall be determined, see figure B.l) 

Bo, Bin = Input and output attenuations at interface B (shall be determined, see figure B.l) 

JLRsnd, JLRrcv = Network Transmit and receive attenuations (shall be determined, see figure B.l) 

Esnd = Echo path loss in the test system 

ERLE = echo return loss enhancement (only unknown) 

ERLEsnd = ERLEsndref -Ao -JLRsnd - Bin - Esnd -Bo - ERLE - JLRrcv -Ain 

ERLE = ERLEsndref - ERLEsnd - Ao - JLRsnd - Bin - Esnd - Bo - JLRrcv - Ain 

Bin + Esnd H- Bo = 8 dB => ERLE = ERLEsndref -ERLEsnd -Ao - JLRsnd - 8 dB -JLRrcv -Ain) 

IfECon:ERLE>25dB 

IfECoff:ERLE> 1 dB 



ETSI 



58 



ETSI TS 102 929 V2.1.2 (2013-03) 



B.2.1 Tests with test signals based on Composite Source Signal 
(CSS) 

B. 2.1.1 Answer tones + 01 6 



Test number 


1.1.1.1;ANS(fromB) + C16 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal CI 6 to Interface A and determine ERLEsndref 

• Establishing a new call from A to B and reset EC 

• Apply signal ANS to Interface B 

• Apply signal CI 6 to Interface A and determine ERLEsnd after sending 
ANS (from B) 


Requirement 


Establishing a new call from A to B the EC is active (EC on). 

After the receiving ANS from B, the EC will not change the state (EC on). 

■=> ERLE = ERLEsndref - ERLEsnd - Ac - JLRsnd - Bin - Esnd - Bo - 
JLRrcv - Ain 

1 ) Before receiving ANS; ECon => ERLE > 25 dB 

2) After the receiving ANS; ECon => ERLE > 25 dB 


Note: 





Test number 


1.1.1.2; ANSam (from B) + C16 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal C1 6 to Interface A and determine ERLEsndref 

• Establishing a new call from A to B and reset EC 

• Apply signal ANSam to Interface B 

• Apply signal C1 6 to Interface A and determine ERLEsnd after sending 
for ANSam (from B) 


Requirement 


Establishing a new call from A to B the EC is active (EC on). 
After the receiving ANSam from B, the EC will not change the state (EC on). 
■=> ERLE = ERLEsndref - ERLEsnd - Ac - JLRsnd - Bin - Esnd - Bo - 
JLRrcv - Ain 

1 ) Before receiving ANSam; ECon => ERLE > 25 dB 

2) After the receiving ANSam; ECon => ERLE > 25 dB 


Note: 





Test number 


1.1.1.3; /ANS (from B) + CI 6 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal CI 6 to Interface A and determine ERLEsndref to ensure 
that ERLSND is to be set to 8 dB 

• Establishing a new call from A to B and reset EC 

• Apply signal /ANS to Interface B 

• Apply signal C1 6 to Interface A and determine ERLEsnd after sending 
/ANS (from B) 


Requirement 


Establishing a new call from A to B the EC is active (EC on). 

After the receiving /ANS from B, the EC will change the state (EC off). 

■* ERLE = ERLEsndref - ERLEsnd - Ac - JLRsnd - Bin - Esnd - Bo - 
JLRrcv - Ain 

1 ) Before receiving /ANS; ECon => ERLE > 25 dB 

2) After the receiving /ANS; ECoff => ERLE > 1 dB 


Note: 





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59 



ETSI TS 102 929 V2.1.2 (2013-03) 



Test number 


1 .1 .1 .4; /ANSam (from B) + CI 6 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal CI 6 to Interface A and determine ERLEsndref 

• Establishing a new call from A to B and reset EC 

• Apply signal /ANSam to Interface B 

• Apply signal CI 6 to Interface A and determine ERLEsnd 
after sending /ANSam (from B) 


Requirement 


Establishing a new call from A to B the EC is active (EC on). 

After the receiving /ANSam from B, the EC will change the state (EC off). 

<> ERLE = ERLEsndref - ERLEsnd - Ao - JLRsnd - Bin - Esnd - Bo - 
JLRrcv - Ain 

1) Before receiving /ANSam; ECon => ERLE > 25 dB 

2) After the receiving /ANSam; ECoff => ERLE > 1 dB 


Note: 





B.2.1 .2 Answer tones + first fax frame + C1 6 



Test number 


1 .1 .2.1 ; ANS (from B) + FAX (from B) + 01 6 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal CI 6 to Interface A and determine ERLESNDREF 

• Establishing a new call from A to B and reset EC 

• Apply signal ANS to Interface B 

• Apply signal FAX to Interface B 

• Apply signal CI 6 to Interface A and determine ERLEsnd after sending 
ANS (from B) 


Requirement 


Establishing a new call from A to B the EC is active (EC on). 

After the receiving ANS from B, the EC will not change the state (EC on) 

■=> ERLE = ERLEsndref - ERLEsnd - Ao - JLRsnd - Bin - Esnd - Bo - 
JLRrcv - Ain 

1 ) Before receiving ANS; ECon => ERLE > 25 dB 

2) After the receiving ANS; ECon => ERLE > 25 dB 


Note: 





Test number 


1.1.2.2; ANSam (from B) + FAX (from B) + C16 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal CI 6 to Interface A and determine ERLEsndref 

• Establishing a new call from A to B and reset EC 

• Apply signal ANSam to Interface B 

• Apply signal FAX to Interface B 

• Apply signal CI 6 to Interface A and determine ERLEsnd 
after sending for ANSam (from B) 


Requirement 


Establishing a new call from A to B the EC is active (EC on). 
After the receiving ANSam from B, the EC will not change the state (EC on) 
■=> ERLE = ERLEsndref - ERLEsnd - Ao - JLRsnd - Bin - Esnd - Bo - 
JLRrcv - Ain 

1 ) Before receiving ANSam; ECon => ERLE > 25 dB 

2) After the receiving ANSam; ECon => ERLE > 25 dB 


Note: 





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60 



ETSI TS 102 929 V2.1.2 (2013-03) 



Test number 


1.1.2.3; /ANS (from B) + FAX (from B) + C16 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal C1 6 to Interface A and determine ERLEsndref 

• Establishing a new call from A to B and reset EC 

• Apply signal /ANS to Interface B 

• Apply signal FAX to Interface B 

• Apply signal C1 6 to Interface A and determine ERLEsnd 
after sending /ANS (from B) 


Requirement 


Establishing a new call from A to B the EC is active (EC on). After the 
receiving /ANS from B, the EC will change the state (EC off). 

"^ ERLE = ERLEsndref - ERLEsnd - Ao - JLRsnd - Bin - Esnd - Bo - 
JLRrcv - Ain 

1 ) Before receiving /ANS; ECon => ERLE > 25 dB 

2) After the receiving /ANS; ECoff => ERLE > 1 dB 


Note: 





Test number 


1.1.2.4 /ANSam (from B) + FAX (from B) + C16 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal C1 6 to Interface A and determine ERLEsndref 

• Establishing a new call from A to B and reset EC 

• Apply signal /ANSam to Interface B 

• Apply signal FAX to Interface B 

• Apply signal C1 6 to Interface A and determine ERLEsnd 
after sending /ANSam (from B) 


Requirement 


Establishing a new call from A to B the EC is active (EC on). 

After the receiving /ANSam from B, the EC will change the state (EC off). 

■=> ERLE = ERLEsndref - ERLEsnd - Ao - JLRsnd - Bin - Esnd - Bo - 
JLRrcv - Ain 

1) Before receiving /ANSam; ECon => ERLE > 25 dB 

2) After the receiving /ANSam; ECoff => ERLE > 1 dB 


Note: 





B.2.1 .3 Tests with test signals based on tine Use of tine CI call signal and 
exchange of CM/JM menu signals + C1 6 



Test number 


1.1.3.1 /ANSam + 4x JM/6xCM + CJ 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal C1 6 to Interface A and determine ERLErcvref 

• Establishing a new call from A to B and reset EC 

• Apply signal /ANSam + 4 x JM to Interface B, and time-synchronously 

• Apply signal 6 x CM + CJ to Interface A 

• Apply signal C16 to Interface A and determine ERLErcv after sending 
/ANSam + 4 x JM (from B) 


Requirement 


Establishing a new call from A to B the EC is active (EC on). 
After the receiving /ANSam from B, the EC will change the state (EC off). 
>* ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving /ANSam+ 4 x JM; ECon => ERLE > 25 dB 

2) After the receiving /ANSam; ECoff => ERLE > 1 dB 


Note: see figure 3 





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61 



ETSI TS 102 929 V2.1.2 (2013-03) 



B.2.1 .4 Tests with test signals based on DTMF 



B.2.1.4.1 Answer tones + D1 6 



Test number 


1.1.4.1;ANS(fromB) + D16 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal D1 6 to Interface A and determine ERLESNDREF 

• Establishing a new call from A to B and reset EC 

• Apply signal ANS to Interface B 

• Apply signal D16 to Interface A and determine ERLESND after 
sending ANS (from B) 


Requirement 


Establishing a new call from A to B the EC is active (EC on). 

After the receiving ANS from B, the EC will not change the state (EC on) 

■=> ERLE = ERLEsndref - ERLEsnd - Ao - JLRsnd - Bin - Esnd - Bo - 
JLRrcv - Ain 

1 ) Before receiving ANS; ECon => ERLE > 25 dB 

2) After the receiving ANS; ECon => ERLE > 25 dB 


Note: 





Test number 


1 .1 .4.2; ANSam (from B) + D1 6 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal D1 6 to Interface A and determine ERLESNDREF 

• Establishing a new call from A to B and reset EC 

• Apply signal ANSam to Interface B 

• Apply signal D1 6 to Interface A and determine ERLEsnd after sending 
for ANSam (from B) 


Requirement 


Establishing a new call from A to B the EC is active (EC on). 

After the receiving ANS from B, the EC will not change the state (EC on) 

■=> ERLE = ERLEsndref - ERLEsnd - Ao - JLRsnd - Bin - Esnd - Bo - 
JLRrcv - Ain 

1 ) Before receiving ANSam; ECon => ERLE > 25 dB 

2) After the receiving ANSam; ECon => ERLE > 25 dB 


Note: 


ERLsND is to be set to 8 dB; ERLE >25 dB 



Test number 


1.1.4.3;/ANS(fromB) + D16 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal D1 6 to Interface A and determine ERLESNDREF to 
ensure that ERLSND is to be set to 8 dB 

• Establishing a new call from A to B and reset EC 

• Apply signal /ANS to Interface B 

• Apply signal D16 to Interface A and determine ERLESND after 
sending /ANS (from B) 


Requirement 


Establishing a new call from A to B the EC is active (EC on). 

After the receiving /ANS from B, the EC will change the state (EC off). 

■=> ERLE = ERLEsndref - ERLEsnd - Ao - JLRsnd - Bin - Esnd - Bo - 
JLRrcv - Ain 

1) Before receiving /ANS; ECon => ERLE > 25 dB 

2) After the receiving /ANS; ECoff => ERLE > 1 dB 


Note: 





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62 



ETSI TS 102 929 V2.1.2 (2013-03) 



Test number 


1.1.4.4; /ANSam (from B) + D16 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal D1 6 to Interface A and determine ERLEsndref 

• Establishing a new call from A to B asnd reset EC 

• Apply signal /ANSam to Interface B 

• Apply signal D1 6 to Interface A and determine ERLEsnd after sending 
/ANSam (from B) 


Requirement 


Establishing a new call from A to B the EC is active (EC on). 

After the receiving /ANSam from B, the EC will change the state (EC off). 

■=> ERLE = ERLEsndref - ERLEsnd - Ao - JLRsnd - Bin - Esnd - Bo - 
JLRrcv - Ain 

1) Before receiving /ANSam; ECon => ERLE > 25 dB 

2) After the receiving /ANSam; ECoff => ERLE > 1 dB 


Note: 





B.2.1 .5 Tests with test signals based on tine Use of tine CI call signal and 
exchange of CM/JM menu signals + D16 



Test number 


1 .1 .5.1 ; /ANSam + 4 x JM / 6 x CM + CJ 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal D16 to Interface A and determine ERLErcvref 

• Establishing a new call from A to B and reset EC 

• Apply signal /ANSam + 4 x JM to Interface B, and time-synchronously 
apply signal 6 x CM + CJ to Interface A 

• Apply signal D1 6 to Interface A and determine ERLErcv after sending 
/ANSam + 4 x JM (from B) 


Requirement 


Establishing a new call from A to B the EC is active (EC on). 
After the receiving /ANSam from B, the EC will change the state (EC off). 
■=> ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving /ANSam+ 4 x JM; ECon => ERLE > 25 dB 

2) After the receiving /ANSam; ECoff => ERLE > 1 dB 


Note: see figure 3 





B.3 Tests with echo simulation at Interface A 

The measurement setup is shown in figure B.3. 



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63 



ETSI TS 102 929 V2.1.2 (2013-03) 




Figure B.3: measurement setup for echo simulation 

The levels marked as R and R - ERLrcv shall match at the respective points of the network. 

ERLrcv is to be set to 8 dB. Because network echo cancellers are tested in G. 168 with ERL of 6 dB, even a small 
maladjustment of the levels in the complete system can lead into the situation that the EC does not consider the echo as 
echo but as near end speech. Therefore a safety margin of 2 dB is built in. 

ERLErcvdref = Transmitted signal at interface B 

ERLErcv = Received signal measured at interface B 

Ao, Ain = Input and output attenuation Interface A (shall be determined, see figure B.l) 

Bo, Bin = Input and output attenuations at interface B (shall be determined, see figure B.l) 

JLRsnd, JLRrcv = Network Transmit and receive attenuations (shall be determined, see figure B.l) 

Esnd = Echo path loss in the test system 

ERLE = echo return loss enhancement (only unknown) 

ERLErcv = ERLErcvref -Bo -JLRrcv - Ain - Ercv -Ao - ERLE - JLRsnd -Bin 

ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - JLRsnd -Bin 

Ain + Ercv H- Ao = 8 dB => ERLE = ERLErcvref -ERLErcv -Bo - JLRrcv - 8 dB -JLsnd -Bin 

IfECon:ERLE>25dB 

IfECoff:ERLE> 1 dB 



ETSI 



64 



ETSI TS 102 929 V2.1.2 (2013-03) 



B.3.1 Tests with test signals based on CSS 



B. 3.1.1 Answer tones + CI 6 



Test number 


2.1.1.1;ANS(from A) + C16 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal CI 6 to Interface B and determine ERLErcvref 

• Establishing a new call from B to A and reset EC 

• Apply signal ANS to Interface A 

• Apply signal CI 6 to Interface B and determine ERLErcv after sending 
ANS (from A) 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 
After the receiving ANS from A, the EC will not change the state (EC on). 
■=> ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving ANS; ECon => ERLE > 25 dB 

2) After the receiving ANS; ECon => ERLE > 25 dB 


Note: 





Test number 


2.1 .1.2; ANSam (from A) + C16 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal CI 6 to Interface Band determine ERLErcvref 

• Establishing a new call from B to A and reset ECApply signal ANSam 
to Interface A 

• Apply signal CI 6 to Interface B and determine ERLErcv after sending 
ANSam (from A) 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 
After the receiving ANSam from A, the EC will not change the state (EC on). 
■=> ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving ANSam; ECon => ERLE > 25 dB 

2) After the receiving ANSam; ECon => ERLE > 25 dB 


Note: 





Test number 


2.1 .1.3; /ANS (from A) + CI 6 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal C1 6 to Interface B and determine ERLErcvref 

• Apply signal /ANS to Interface A 

• Establishing a new call from B to A and reset EC 

• Apply signal C1 6 to Interface B and determine ERLErcv after sending 
/ANS (from A) 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 

After the receiving /ANS from A, the EC will change the state (EC off). 

■=> ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving /ANS; ECon => ERLE > 25 dB 

2) After the receiving /ANS; ECoff => ERLE > 1 dB 


Note: 





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65 



ETSI TS 102 929 V2.1.2 (2013-03) 



Test number 


2.1 .1.4; /ANSam (from A) + C16 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal C1 6 to Interface B and determine ERLErcvref 

• Establishing a new call from B to A and reset EC 

• Apply signal ANSam to Interface A 

• Apply signal C1 6 to Interface B and determine ERLErcv after sending 
ANS (from A) 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 
After the receiving /ANSam from A, the EC will change the state (EC off). 
■=> ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving /ANSam; ECon => ERLE > 25 dB 

2) After the receiving /ANSam; ECoff => ERLE > 1 dB 


Note: 





B.3.1 .2 Answer tones + first fax frame + C1 6 



Test number 


2.1 .2.1 ; ANS (from A) + FAX (from B) + 01 6 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal C1 6 to Interface B and determine ERLERCVREF 

• Establishing a new call from B to A and reset EC 

• Apply signal ANS to Interface A 

• Apply signal FAX to Interface A 

• Apply signal C1 6 to Interface B and determine ERLErcv after sending 
ANS (from A) 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 
After the receiving ANS from A, the EC will not change the state (EC on. 
■=> ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving ANS; ECon => ERLE > 25 dB 

2) After the receiving ANS; ECon => ERLE > 25 dB 


Note: 





Test number 


2.1.2.2; ANSam (from A)+ FAX (from A)+ CI 6 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal CI 6 to Interface B and determine ERLErcvref 

• Establishing a new call from B to A and reset EC 

• Apply signal ANS to Interface A 

• Apply signal FAX to Interface A 

• Apply signal C16 to Interface B and determine ERLErcv after sending 
ANSam (from A) 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 
After the receiving ANSam from A, the EC will not change the state (EC on). 
■^ ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving ANSam; ECon => ERLE > 25 dB 

2) After the receiving ANSam; ECon => ERLE > 25 dB 


Note: 





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66 



ETSI TS 102 929 V2.1.2 (2013-03) 



Test number 


2.1 .2.3; /ANS (from A) + FAX (from A)+ CIS 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal C1 6 to Interface B and determine ERLErcvref 

• Establishing a new call from B to A and reset EC 

• Apply signal ANS to Interface A 

• Apply signal FAX to Interface A 

• Apply signal C1 6 to Interface B and determine ERLErcv after sending 
/ANS (from A) 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 
After the receiving /ANS from A, the EC will not change the state (EC off). 
"^ ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving /ANS; ECon => ERLE > 25 dB 

2) After the receiving /ANS; ECoff => ERLE > 1 dB 


Note: 





Test number 


2.1.2.4; /ANSam (from A) + FAX (from A)+C16 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal C1 6 to Interface B and determine ERLErcvref 

• Establishing a new call from B to A and reset EC 

• Apply signal ANSam to Interface A 

• Apply signal FAX to Interface A 

• Apply signal C1 6 to Interface B and determine ERLErcv after sending 
/ANSam (from A) 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 
After the receiving /ANSam from A, the EC will not change the state (EC off). 
■=> ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving /ANSam; ECon => ERLE > 25 dB 

2) After the receiving /ANSam; ECoff => ERLE > 1 dB 


Note: 





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67 



ETSI TS 102 929 V2.1.2 (2013-03) 



B.3.1 .3 Tests with test signals based on tine Use of tiie CI call signal and 
exchange of CM/JM menu signals + C1 6 



Test number 


2.1 .3.1 ; ANSam + 4 >c JM / 6 x CM + CJ 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal CI 6 to Interface B and determine ERLErcvref 

• Establishing a new call from B to A and reset EC 

• Apply signal /ANSam + 4 x JM to Interface A, and time-synchronously 
apply signal 6 x CM + CJ to Interface B 

• Apply signal CI 6 to Interface B and determine ERLErcv after sending 
/ANSam -i- 4 x JM (from A) 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 
After the receiving ANSam from A, the EC will change the state (EC off). 
■=> ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving /ANSam+ 4 x JM; ECon => ERLE > 25 dB 

2) After the receiving /ANSam; ECoff => ERLE > 1 dB 


Note: see figure 1 of 
Recommendation ITU-T V. 8 [1] 





B.3.1 .4 Tests with test signals based on DTMF 



B.3.1. 4.1 



Answer tones -i- D16 



Test number 


2.1.4.1;ANS(from A) + D16 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal D1 6 to Interface B and determine ERLErcvref 

• Establishing a new call from B to A and reset EC 

• Apply signal ANS to Interface A 

• Apply signal D1 6 to Interface B and determine ERLErcv after sending 
ANS (from A) 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 
After the receiving ANS from A, the EC will not change the state (EC on) 
■=> ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving ANS; ECon => ERLE > 25 dB 

2) After the receiving ANS; ECon => ERLE > 25 dB 


Note: 





Test number 


2.1.4.2; ANSam (from A) + D16 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal D1 6 to Interface B and determine ERLErcvref 

• Establishing a new call from B to A and reset EC 

• Apply signal ANSam to Interface A 

• Apply signal D1 6 to Interface B and determine ERLErcv after sending 
ANS (from A) 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 
After the receiving ANSam from A, the EC will not change the state (EC on). 
■=> ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving ANSam; ECon => ERLE > 25 dB 

2) After the receiving ANSam; ECon => ERLE > 25 dB 


Note: 





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68 



ETSI TS 102 929 V2.1.2 (2013-03) 



Test number 


2.1.4.3;/ANS(from A) + D16 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal D1 6 to Interface B and determine ERLErcvref 

• Establishing a new call from B to A and reset EC 

• Apply signal /ANS to Interface A 

• Apply signal D1 6 to Interface B and determine ERLErcv after sending 
/ANS (from A) 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 

After the receiving /ANS from A, the EC will change the state (EC off). 

■=> ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving /ANS; ECon => ERLE > 25 dB 

2) After the receiving /ANS; ECoff => ERLE > 1 dB 


Note: 





Test number 


2.1.4.4; /ANSam (from A) + D16 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal D1 6 to Interface B and determine ERLErcvref 

• Establishing a new call from B to A and reset EC 

• Apply signal /ANSam to Interface A 

• Apply signal D1 6 to Interface B and determine ERLErcv after sending 
/ANSam (from A) 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 
After the receiving /ANSam from A, the EC will change the state (EC off). 
■=> ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving /ANSam; ECon => ERLE > 25 dB 

2) After the receiving /ANSam; ECoff => ERLE > 1 dB 


Note: 





B.3.1 .5 Tests with test signals based on tine Use of tine CI call signal and 
exchange of CM/JM menu signals + D16 



Test number 


2.1 .5.1 ; /ANSam + 4xJM/6xCM + CJ 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal D16 to Interface B and determine ERLErcvref 

• Establishing a new call from B to A and reset EC 

• Apply signal /ANSam + 4 x JM to Interface A, and time-synchronously 
apply signal 6 x CM -i- CJ to Interface B 

• Apply signal D16 to Interface B and determine ERLErcv after sending 
/ANSam -i- 4 x JM (from A) 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 
After the receiving /ANSam from A, the EC will change the state (EC off). 
'=^ E RLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ao - 
JLRsnd -Bin 

1 ) Before receiving /ANSam+ 4 x JM; ECon => ERLE > 25 dB 

2) After the receiving /ANSam; ECoff => ERLE > 1 dB 


Note: See figure 3. 





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B.4 Tests with test signals based on the data rate 
change between V.34 and V.17 Fax Terminals 



Test number 


3.1 .1 /ANSam + 4 x JM / 6 x CM + CJ data rate change between V.34 and 
V.17 Fax Terminals 


Measurement procedure 


• Establishing a new call from A to B and reset EC 

• Apply signal D16 to Interface A and determine ERLErcvref 

• Establishing a new call from A to B and reset EC 

• Apply signal /ANSam + 4 x JM to Interface B, and time-synchronously 
apply signal 6 x CM + CJ to Interface A 

• Apply signal D1 6 to Interface A and determine ERLErcv after sending 
/ANSam + 4 x JM (from B) 

• After 400 ms signal break apply signal C1 6 to Interface A and 
determine ERLErcv 


Requirement 


Establishing a new call from A to B the EC is active (EC on). 
After the receiving /ANSam from B, the EC will change the state (EC off). 
■=> ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ac - 
JLRsnd -Bin 

1 ) Before receiving /ANSam+ 4 x JM; ECon => ERLE > 25 dB 

2) After the receiving /ANSam; ECoff => ERLE > 1 dB 

3) After 400 ms signal break ECon => ERLE > 25 dB 


Note: See figure 3. 





Test number 


3.1.2 /ANSam + 4 x JM / 6 x CM + CJ, data rate change between V.34 and 
V.17 Fax Terminals 


Measurement procedure 


• Establishing a new call from B to A and reset EC 

• Apply signal CI 6 to Interface B and determine ERLErcvref 

• Establishing a new call from B to A and reset EC 

• Apply signal /ANSam + 4 x JM to Interface A, and time-synchronously 
apply signal 6 x CM -i- CJ to Interface B 

• Apply signal CI 6 to Interface B and determine ERLErcv after sending 
/ANSam -h 4 x JM (from A) 

• After 400 ms signal break apply signal C1 6 to Interface B and 
determine ERLErcv 


Requirement 


Establishing a new call from B to A the EC is active (EC on). 
After the receiving /ANSam from A, the EC will change the state (EC off). 
^ ERLE = ERLErcvref- ERLErcv -Bo -JLRrcv - Ain - Ercv -Ac - 
JLRsnd -Bin 

1 ) Before receiving /ANSam+ 4 x JM; ECon => ERLE > 25 dB 

2) After the receiving /ANSam; ECoff => ERLE > 1 dB 

3) After 400 ms signal break ECon => ERLE > 25 dB 


Note: See figure 3. 





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Tanmlnal 






70 ± 5 ms 70 ± 5 ms 



i 


B 


B 


LI 


L2 


B 



ANSam 


JM 




PPti 


ALT 


MPtl 


MPh 


E 


Flaos 


TSI 


DCS 


Flags 


-1- 
(Ncte) 



S 


SPP 


Bl 


Qala 



) u ; 



Rags 



pTlmary 

Equali^ti r Modem F'arametgr 

Nfliwork imLeracHon Urt&Probirifl Training Exchange 



Primary 
Channel 
T.30 Fajt HandShaWng iRMync. 



TI)G2S8D(^aii[I1Q7 



NOTE - The HlriTiy «f LcscisccuLivt Is ifihall be (oUuweJ by the 41 csf strajiibled imes defined in l2.6JyV.34. 



Figure B.4: Typical V.34 fax start-up sequence 



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71 ETSI TS 1 02 929 V2.1 .2 (201 3-03) 



Annex C (informative): 

Features of V.17 Fax and V.34 Fax 

C.1 Features of V.17 Fax (V.17 Fax IVIodem) 

Half-duplex mode of operation for fax applications. 

QAM is used for the channel with synchronous line transmission at 2 400 baud. 

Data signalling rates: 14 400 bps, 12 000 bps, 9 600 bps, 7 200 bps, 4 800 bps and 2 400 bps synchronous. 

Trellis coding at rates from 7 200 bps to 14 000 bps. 

Exchange of rate sequences is provided during start-up to establish the data-rate, coding, and any other special 
facilities. 

The frequency carrier operates at 1 800 Hz. 

Transmitted power levels conform to V.2. 

Modulation rate is 2 400 symbols/s. 

Supports V.24 interchange circuits. 

C.2 V.34 High-Speed Fax 
C.2.1 Features 

• Fully compliant Group 3 Facsimile Support. 

• Full and half duplex modes. 

• Primary data channel supports 14 data rates in the range of 2 400 bps to 33 600 bps, in increments of 
2 400 bps. 

• Control channel rates are 1 200 bps and 2 400 bps. 

C.2.2 The Recommendation ITU-T V.34 Fax Standard 

The V.34 fax standard was derived from the V.34 data modem standard established by the International 
Telecommunications Union (ITU). The V.34 data modem standard is a full-duplex implementation for sending and 
receiving data across telephone lines with a maximum data rate of 33,6 Kbps. Certain elements of the V.34 data modem 
standard were eliminated for V.34 fax while new features, such as a control channel and mandatory ECM, were added 
to enable fast and reliable fax transmission. 



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Data Rates 

Supported 

(Kbps) 

2,4 
4,8 
7,2 
9,6 

12 
14,4 
16,8 
19,2 
21,6 

24 
26,4 
28,8 
31,2 
33,6 


V.27 
V.29 


ITU Standard 
V.I 7 


V.34 


X 




X 


X 


X 


X 


X 


X 


X 


X 


X 




X 


X 


X 


X 




X 


X 


X 


X 


X 


X 


X 


X 



Figure C.1 : Comparison between Fax IVIodulation Speeds 



C.3 The V.34 Fax Connection and Session 

In order to understand the benefits of the V.34 fax standard, it is first necessary to understand how a fax transmission 
works. V.34 session management and setup were designed with a similar mechanism to legacy handshaking procedures. 
The first step of a fax session is to establish a "handshake" between the sending and the receiving devices. During 
handshaking, the sending and receiving devices negotiate key parameters for how the fax call should be set up such as 
determining what is the highest transmission speed supported by both devices. The handshaking process itself is 
performed at 300 bps in legacy devices. In V.34 fax capable devices, handshaking is performed at a much faster data 
rate of 1,2 Kbps. The result is a handshake time that is reduced from approximately 16 seconds of legacy systems to 
9 seconds for V.34. 



16 seconds 



X seconds 





■^ 


^ 






*- 




V.17 


Hands liaking 


Page data 


III 




9 seconds 

&H< 


X!2 seconds 


— ► 


■ ■ ■ 


r 


V.34 


Hands liakiiig 


Page date 






Start of call 












TIM 


E 



Figure C.2: Time-wise Comparison Between V.34 and V.17 Fax 



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ETSI TS 102 929 V2.1.2 (2013-03) 



After handshaking is complete, the next stage of a fax session is the transmission of the actual fax page data. The 
retraining and re-synchronization process takes place after each page is transmitted in legacy schemes, where 
capabilities such as supported modulation and transfer are renegotiated. In case of error in the transmission, entire pages 
may need to be retransmitted. This cycle of page data retrain and retransmit repeats until the fax call is completed, and 
account for significant inefficiency of legacy fax machines. V.34 provides the most extensive range of supported data 
transmission rates, allowing it to optimize both speed and reliability over a wide range of line conditions. With V.34, 
fax page data is transmitted at 33,6 Kbps, twice the speed of V.17. In addition, V.34 uses ECM (Error Correction Mode) 
as a mandatory feature that handles page transmission error in a much more efficient way. 



C.4 ECM as a Mandatory Feature 

ECM is a mandatory feature for V.34 fax as opposed to V.17, where it is optional. The ECM protocol was designed to 
automatically detect and correct errors in the fax transmission process caused by factors such as telephone line noise. 
The page data to be transferred is divided into small blocks of data called Octets. Once all octets are received, they are 
examined using check-sums. 



Pi^ Dita 





01 




02 






03 


... 


On 





Page is hioihen into Octets and 
framed 



On 



03 



02 



01 







Foi example^ Octets 1 and 3 are 
c orn|) ted during transmijsiDn 




03 



01 




Oc tefe 1 and 3 are retransmitted 




01 




02 






03 


... 




On 





Pi^ Dati 



Once an Octets are receved, tliey are 
ordered to recanstruict the page dab 



Figure C.3: ECM Enabled Fax Transmission 

If any errors in the checksums are detected, the receiving fax device signals the transmitting fax device to retransmit the 
octets that were received incorrectly. The transmitter then retransmits only the needed blocks rather than the whole 
page. Once, all octets are received correctly, they are ordered and the page data is reconstructed by removing the octet 
frame and signalling flags. Generally, this results in a faster and more successful fax transmission than in a scenario 
where entire page data is retransmitted once or multiple times. 

Introduction to V.34 High-Speed Fax [i.8]. Website: http://www.gaoresearch.com/V34Fax/V34Fax.php . 



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History 



Document history 


VI. 1.1 


April 2011 


Publication 


V2.1.1 


August 2012 


Publication 


V2.1.2 


March 2013 


Publication 















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