SIST I-ETS 300 245-6 E1:2003

• Abstract:

  To standardise electroacoustical characteristics for loudspeaking and handsfree telephony terminals using G.722 coding

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.080 - Integrated Services Digital Network (ISDN)
• Technical Committee: SS EIT - Technical Board for the electrotechnical, information technology and telecommunications fields
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Dec-2003
• Due Date: 01-Dec-2003
• Completion Date: 01-Dec-2003
• Ref Project: ETSI I-ETS 300 245-6 ed.1 (1996-01) - Integrated Services Digital Network (ISDN); Technical characteristics of telephony terminals; Part 6: Wideband (7 kHz), loudspeaking and hands free telephony

SIST I-ETS 300 245-6 E1:2003 is the Slovenian identical version of I-ETS 300 245-6 Edition 1 from ETSI. It specifies the signalling characteristics, in-band protocol, and electroacoustic characteristics for wideband 7 kHz loudspeaking and hands free ISDN telephony terminals used with the telephony 7 kHz teleservice.

What does SIST I-ETS 300 245-6 E1:2003 specify?

SIST I-ETS 300 245-6 E1:2003 defines the requirements for hands free and loudspeaking ISDN telephony terminals that support wideband 7 kHz speech. In practice, it tells manufacturers and test labs how the terminal shall behave on the network side and at the acoustic interfaces.

The scope places the terminals at the basic user-network interface on the coincident S and T reference point of the pan-European ISDN. It also states that wideband terminals still need to support the 3.1 kHz telephony teleservice, with the narrowband requirements taken from the other parts of the series.

The document is organized into clauses for scope, normative references, definitions and abbreviations, D-channel characteristics, in-band signalling characteristics, and transmission characteristics. It then gives one normative annex for test methods, one informative annex for delay measurement methods, and one informative bibliography.

Annex	What it covers
Annex A	Normative test methods, including test room conditions, setups, calibration, and measurement procedures
Annex B	Informative delay measurement methods using cross-correlation or group delay
Annex C	Bibliography

What are the key requirements of SIST I-ETS 300 245-6 E1:2003?

Signalling and operating modes

SIST I-ETS 300 245-6 E1:2003 requires the wideband hands free terminal to use the same D-channel and in-band signalling characteristics as the wideband handset terminal in Part 5. That means the control side of the terminal is aligned with the rest of the series, so interoperability depends on the same signalling behavior.

The digital interface is defined as a 0 dBr point. This gives a common reference for level measurements, which matters when different terminals and test systems are compared.

The standard also requires operation with CCITT Recommendation G.711 and CCITT Recommendation G.722 coding. A-law is the default narrowband coding, while μ-law shall also be implemented; the calling terminal is responsible for using the correct law when the network region is known.

Speech coding and fallback

For wideband operation, modes 1, 2, and 3 use G.722 coding, and the lower sub-band is encoded with 6 bits. In modes 2 and 3, some bit capacity is reserved for the auxiliary data channel, so the audio and data functions are designed to coexist.

When a terminal detects μ-law use, it shall decode accordingly, and the document ties this behavior to signalling or other detection means. For terminals that also support handset operation, the handset-related wideband requirements and fallback behavior are taken from Part 5.

This matters in practice because a compliant terminal must handle both wideband and narrowband calls, and it must fall back cleanly to 3.1 kHz telephony and PSTN operation when required.

Acoustic performance

The standard limits the receiving volume control to at least 15 dB range and says that changing the volume control shall not alter sending sensitivity. That protects the microphone path from accidental user changes and keeps the send level stable during use.

For the speech path, the document sets response masks for both sending and receiving sensitivity-frequency behavior. It also gives nominal loudness rating targets for sending and receiving, with stated tolerances, and a specific requirement for the range covered by the receiving volume control.

These requirements matter because they determine whether speech sounds natural and balanced at both ends of the call. They are measured from the mouth side to the digital interface for sending, and from the digital interface to the acoustic measurement point for receiving.

Echo, stability, distortion, noise, and delay

SIST I-ETS 300 245-6 E1:2003 requires Weighted Terminal Coupling Loss (TCLw) of at least 35 dB and stability loss of at least 6 dB across the stated frequency range. In practice, this is the main protection against echo and howling in hands free and loudspeaking use.

The standard also sets total distortion limits for sending and receiving, with measurements at several tone levels and frequencies. It adds limits for out-of-band signals, so unwanted image components outside the speech band are controlled.

Noise is limited in both directions, and the total sending-plus-receiving delay shall be less than 10 ms. The delay requirement can be shown by supplier declaration based on the methods in Annex B, or by another documented approach.

What terms does SIST I-ETS 300 245-6 E1:2003 define?

• Acoustic Reference Level (ARL) - The acoustic level that corresponds to -10 dBm0 at the digital interface.
• Hands Free Reference Point (HFRP) - The free-field calibration point on the axis of the artificial mouth, 50 cm from the lip plane.
• hands free telephony function - A mode where no handset or other transducer is held to the ear, and the microphone and loudspeaker arrangement can vary.
• loudspeaking function - A mode where the handset is in the normal position and the received signal is presented by loudspeaker(s) as well.
• Terminal Coupling Loss (TCL) - The frequency-dependent coupling loss between the receiving and sending ports caused by electrical, acoustic, and mechanical coupling.
• Weighted Terminal Coupling Loss (TCLw) - TCL calculated with the weighting method from ITU-T Recommendation G.122.
• telephony 7 kHz teleservice - A real-time service for exchanging 7 kHz or 3.1 kHz speech over one circuit-mode 64 kbit/s connection.

Who uses SIST I-ETS 300 245-6 E1:2003?

SIST I-ETS 300 245-6 E1:2003 is used by terminal manufacturers, acoustic test laboratories, and telecom quality teams that work on ISDN loudspeaking and hands free terminals. It is also relevant to buyers and procurement staff who need a clear specification for wideband telephony equipment.

Engineers use it to design the speech path, coding behavior, and echo performance. Test labs use it to set up the required room, reference codec, artificial mouth, and measurement methods. Quality and compliance teams use it to check whether a terminal meets the stated masks, loss targets, noise limits, and delay requirements.

What changed in SIST I-ETS 300 245-6 E1:2003 from the previous edition?

SIST I-ETS 300 245-6 E1:2003 is identical to I-ETS 300 245-6 Edition 1.

Which standards are used with SIST I-ETS 300 245-6 E1:2003?

• I-ETS 300 245-1 - Provides the general requirements for the telephony terminals series, and Part 6 applies in conjunction with it.
• I-ETS 300 245-3 - Provides the PCM A-law loudspeaking and hands free requirements used for narrowband operation and some test methods.
• I-ETS 300 245-5 - Provides the wideband handset telephony requirements used for shared signalling and fallback behavior.
• ETS 300 263 - Defines the telephony 7 kHz teleservice that Part 6 is intended to support.
• ETS 300 012 - Gives the basic user-network interface layer 1 specification and test principles, including power supply limits and interface connection rules.
• ITU-T Recommendation G.101 - Defines the transmission plan and the 0 dBr reference used for the digital interface.
• CCITT Recommendation G.711 - Defines PCM voice coding for A-law and μ-law operation.
• CCITT Recommendation G.722 - Defines 7 kHz audio coding within 64 kbit/s and the reference codec used in testing.
• CCITT Recommendation G.725 - Is used for the A-law/μ-law coding check in Annex A, with a note that it was cancelled and replaced by ITU-T Recommendation H.245.
• ITU-T Recommendations P.31, P.34, P.51, P.79 and G.122 - Support the transmission, hands free, artificial mouth, loudness rating, and coupling-loss calculations.
• IEC Publication 651 - Specifies the sound level meter type used in the test methods.
• ISO 3 - Provides the preferred number series used for measurement frequencies.

What does the SIST I-ETS 300 245-6 E1:2003 document contain?

The document contains the main technical requirements for signalling, coding, speech transmission, echo control, noise, and delay for wideband hands free and loudspeaking ISDN terminals. Tables 1 to 6 define which requirements apply and give the masks and limits that the terminal must meet.

Annex A is the practical core for testing. It describes the free-field room conditions, test table placement, artificial mouth setup, codec interface, signal levels, and the measurement steps for sensitivity response, loudness rating, TCLw, stability loss, distortion, out-of-band signals, noise, and G.725 encoding checks.

Annex B gives two alternative methods for measuring delay - cross-correlation and group delay. Annex C lists related documents used for background and context.

SLOVENSKI STANDARD
01-december-2003
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Integrated Services Digital Network (ISDN); Technical characteristics of telephony
terminals; Part 6: Wideband (7 kHz), loudspeaking and hands free telephony
Ta slovenski standard je istoveten z: I-ETS 300 245-6 Edition 1
ICS:
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERIM
EUROPEAN I-ETS 300 245-6
TELECOMMUNICATION January 1996
STANDARD
Source: ETSI TC-TE Reference: T/TE 10-07(F)
ICS: 33.080
ISDN, telephony terminals, 7 kHz, hands free, loudspeaking
Key words:
Integrated Services Digital Network (ISDN);
Technical characteristics of telephony terminals;
Part 6: Wideband (7 kHz), loudspeaking and hands free
telephony
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - [e-mail]
X.400: Internet:
Tel.: [phone] - Fax: [phone]
*
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1996. All rights reserved.

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I-ETS 300 245-6: January 1996
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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I-ETS 300 245-6: January 1996
Contents
Foreword .5
1 Scope .7
2 Normative references.7
3 Definitions and abbreviations .8
3.1 Definitions .8
3.2 Abbreviations .9
4 D-channel characteristics.9
5 In-band signalling characteristics .9
6 Transmission characteristics.10
6.1 Relative level.10
6.2 Signal encoding .10
6.2.1 CCITT Recommendation G.711 encoding.10
6.2.1.1 A-law.10
6.2.1.2 μ-law .10
6.2.2 CCITT Recommendation G.722 encoding.11
6.3 Signal decoding .11
6.3.1 CCITT Recommendation G.711 decoding.11
6.3.1.1 A-law.11
6.3.1.2 μ-law .11
6.3.2 CCITT Recommendation G.722 decoding.11
6.4 Speech transmission characteristics .11
6.4.1 Volume control .11
6.4.2 Requirements applicable to Hands Free Terminal and LoudSpeaking
Telephony.12
6.4.3 Sensitivity-frequency response.12
6.4.3.1 Sending.12
6.4.3.2 Receiving.13
6.4.4 Loudness rating.14
6.4.4.1 Sending Loudness Rating.14
6.4.4.2 Receiving Loudness Rating.14
6.4.5 Terminal Coupling Loss.15
6.4.5.1 Weighted Terminal Coupling Loss .15
6.4.5.2 Stability loss.15
6.4.6 Distortion .15
6.4.6.1 Sending.15
6.4.6.2 Receiving.16
6.4.7 Out-of-band signals.16
6.4.7.1 Discrimination against out-of-band input signals (Sending) 16
6.4.7.2 Spurious out-of-band (Receiving).16
6.4.8 Noise .17
6.4.8.1 Sending.17
6.4.8.2 Receiving.17
6.4.9 Delay .17
Annex A (normative): Test methods.18
A.1 General conditions for testing.18
A.1.1 Testing environment .18
A.1.1.1 Test room .18
A.1.1.2 Testing arrangements .20

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I-ETS 300 245-6: January 1996
A.1.1.2.1 Hands free function. 20
A.1.1.2.2 Loudspeaking function . 21
A.1.2 Power supply limitations. 21
A.1.3 Test equipment interface. 21
A.1.4 Test equipment requirements . 22
A.1.4.1 Electroacoustic equipment. 22
A.1.4.2 Test signals and spectrum measurements. 22
A.1.4.2.1 Standard test signals. 22
A.1.4.2.2 Composite Source Signal . 22
A.1.4.3 Test signals levels . 22
A.1.4.3.1 Sending. 22
A.1.4.3.2 Receiving . 23
A.1.4.4 Test equipment for the digital interface . 23
A.1.4.4.1 Codec specifications . 23
A.1.4.4.2 Analogue interface . 23
A.1.4.4.3 Definition of 0 dBr point. 23
A.1.5 Accuracy of calibrations . 23
A.2 Testing of transmission requirements . 24
A.2.1 Sensitivity-frequency response . 24
A.2.1.1 Sending. 24
A.2.1.2 Receiving . 25
A.2.2 Loudness Rating . 25
A.2.2.1 Sending Loudness Rating. 25
A.2.2.2 Receiving Loudness Rating . 25
A.2.3 Terminal Coupling Loss . 25
A.2.3.1 Weighted Terminal Coupling Loss. 25
A.2.3.2 Stability loss. 26
A.2.4 Distortion . 26
A.2.4.1 Sending. 26
A.2.4.2 Receiving . 26
A.2.5 Out-of-band signals. 26
A.2.5.1 Discrimination against out-of-band input signals (Sending) . 26
A.2.5.2 Spurious out-of-band (Receiving). 26
A.2.6 Noise . 27
A.2.6.1 Sending. 27
A.2.6.2 Receiving . 27
A.2.7 CCITT Recommendation G.725 encoding. 27
Annex B (informative): Delay measurement methods. 28
B.1 Introduction. 28
B.2 Cross-correlation method . 28
B.2.1 Sending . 28
B.2.2 Receiving. 29
B.2.3 Total delay. 29
B.3 Method based on group delay . 29
B.3.1 Sending . 29
B.3.2 Receiving. 30
B.3.3 Total delay. 30
Annex C (informative): Bibliography . 31
History. 32

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I-ETS 300 245-6: January 1996
Foreword
Part 6 of this Interim European Telecommunication Standard (I-ETS) was produced by the Terminal
Equipment (TE) Technical Committee of the European Telecommunication Standards Institute (ETSI).
This Part 6 provides the technical characteristics of hands free Integrated Services Digital Network (ISDN)
telephone terminals suitable to support the telephony 7 kHz teleservice.
An ETSI draft standard may be given I-ETS status as it is regarded either as a provisional solution ahead
of a more advanced standard, or because it is immature and requires a "trial period". The life of an I-ETS
is limited, at first, to three years after which it can be converted into a full European Telecommunication
Standard (ETS), have its life extended for a further two years, be replaced by a new version of the I-ETS
or, finally, be withdrawn.
This is the sixth Part of an I-ETS which comprises eight Parts:
Part 1: General.
Part 2: PCM A-Law, Handset telephony.
Part 3: PCM A-Law, Loudspeaking and hands free telephony.
Part 4: Interface for additional equipment.
Part 5: Wideband (7 kHz) handset telephony.
Part 6: Wideband (7 kHz), loudspeaking and hands free telephony.
Part 7: Locally generated information tones.
Part 8: Speech transmission characteristics when using Low-Delay Code-Excited Linear Prediction
(LD-CELP) coding at 16 kbit/s.
Proposed announcement date
Date of adoption of this I-ETS: 12 January 1996
Date of latest announcement of this I-ETS (doa): 30 April 1996

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I-ETS 300 245-6: January 1996
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I-ETS 300 245-6: January 1996
1 Scope
Part 6 of this I-ETS specifies the signalling characteristics, the in-band protocol and the electroacoustic
characteristics of hands free terminals supporting the telephony 7 kHz teleservice as defined in
ETS 300 263 which is intended for connection to the basic user-network interface at the coincident S and
T reference point of the pan-European ISDN, as provided by European public telecommunications
operators.
Wideband telephone terminals also need to support the telephony 3,1 kHz teleservice. Reference is made
to Parts 1 and 3 of this I-ETS for the electroacoustic requirements relative to the narrow band audio mode.
Part 6 of this I-ETS only specifies the requirements related to hands free and loudspeaking operation.
This Part applies in conjunction with I-ETS 300 245-1 and the additional characteristics specified in this
Part are additional to those in I-ETS 300 245-1.
2 Normative references
This I-ETS incorporates by dated and undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this I-ETS only when incorporated in it by amendment or revision. For undated references the
latest edition of the publication referred to applies.
[1] I-ETS 300 245-5: "Integrated Services Digital Network (ISDN); Technical
characteristics of telephony terminals; Part 5: Wideband (7 kHz) handset
telephony".
[2] ITU-T Recommendation G.101 (1993): "The transmission plan".
[3] CCITT Recommendation G.711 (1988): "Pulse code modulation (PCM) of voice
frequencies".
[4] CCITT Recommendation G.722 (1988): "7 kHz audio coding within 64 kbit/s".
[5] I-ETS 300 245-3: "Technical characteristics of telephony terminals; Part 3: Pulse
Code Modulation (PCM) A-Law, loudspeaking and hands free function".
[6] CCITT Recommendation G.725 (1988): "System aspects for the use of the
7 kHz audio codec within 64 kbit/s".
NOTE: It should be noted that CCITT Recommendation G.725 [6] was cancelled and replaced
by ITU-T Recommendation H.245 at the ITU-T SG 15 meeting held in
November 1995.
[7] ITU-T Recommendation P.31 (1993): "Transmission characteristics for digital
telephones".
[8] ITU-T Recommendation P.34 (1993): "Transmission characteristics of
hands-free telephones".
[9] I-ETS 300 245-2: "Integrated Services Digital Network (ISDN); Technical
characteristics of telephony terminals; Part 2: PCM A-law handset telephony".
[10] ETS 300 012: "Integrated Services Digital Network (ISDN); Basic user-network
interface, Layer 1 specification and test principles".
[11] ITU-T Recommendation P.51 (1993): "Artificial mouth".
[12] IEC Publication 651: "Sound level meters".
[13] ISO 3 (1973): "Preferred numbers - Series of preferred numbers".

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I-ETS 300 245-6: January 1996
[14] ITU-T Recommendation P.79 (1993): "Calculation of loudness ratings for
telephone sets".
[15] ITU-T Recommendation G.122 (1993): "Influence of national systems on
stability talker echo, and listener echo in international connections".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of this Part of the I-ETS, the following definitions apply:
Acoustic Reference Level (ARL): The acoustic level which gives - 10 dBm0 at the digital interface.
active mode: The terminal is activated by an input signal (e.g. input signal level above implemented
threshold level).
Adaptive Differential Pulse Code Modulation (ADPCM): ADPCM algorithms are compression
algorithms that achieve bit rate reduction through the use of adaptive prediction and adaptive quantization
[ITU-T Recommendation G.701 (1993), def. 8004].
call progress monitoring: The loudspeaker is used to monitor the received signals while the voice
transmission in the sending direction is disconnected.
double talk: An operation mode, where two users are speaking simultaneously.
Hands Free Reference Point (HFRP): A point located on the axis of the artificial mouth, at 50 cm from
the lip plane, where the level calibration is made under free field conditions. It corresponds to
measurement point n° 11 defined in ITU-T Recommendation P.51 [11].
hands free telephony function: For free handling no handset or no other equipment with transducers is
held to the ear of the user. If a handset is implemented, then it is placed at a distance from the user.
Normally, the handset is not active. The number, the implementation and the use of microphone(s) and
loudspeaker(s) are not limited.
idle mode: The terminal is not activated by an input signal (e.g. input signal level below implemented
threshold level).
loudness rating: A measure, expressed in decibels, for characterizing the loudness performance of
complete telephone connections or of parts thereof such as sending system, line, receiving system.
loudspeaking function: The handset is used in the normal position. The incoming signal is
simultaneously presented to the user(s) from loudspeaker(s).
modes of operation: The following modes of operation are defined:
mode 0U: 64 kbit/s 3,1 kHz audio to CCITT Recommendation G.711 [3], unframed.
mode 0F: 56 kbit/s 3,1 kHz audio to CCITT Recommendation G.711 [3] truncated to 7 bits,
framed.
mode 1: 64 kbit/s 7 kHz audio to CCITT Recommendation G.722 [4].
mode 2: 56 kbit/s 7 kHz audio to CCITT Recommendation G.722 [4] and up to 6,4 kbit/s data.
mode 3: 48 kbit/s 7 kHz audio to CCITT Recommendation G.722 [4] and up to 14,4 kbit/s data.
NOTE: For modes 0F, 2 and 3 an additional 1,6 kbit/s capacity is reserved for service channel
framing and service control.
Pulse Code Modulation (PCM): A process in which a signal is sampled, and each sample is quantized
independently of other samples and converted by encoding to a digital signal [ITU-T Recommendation
G.701 (1993), def. 8001].
single talk: An operation mode, where only one user is speaking.

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I-ETS 300 245-6: January 1996
Terminal Coupling Loss (TCL): The frequency dependent coupling loss between the receiving port and
sending port of a terminal due to:
- electrical coupling due to crosstalk in the handset cord or within the electrical circuits;
- acoustical coupling at the user interface;
- seismic coupling through the mechanical parts of the terminal.
NOTE 1: The receiving port and the sending port of a digital voice terminal is a 0 dBr point.
NOTE 2: The coupling at the user interface depends on the conditions of use.
Weighted Terminal Coupling Loss (TCLw): The Terminal Coupling Loss calculated using the weighting
of ITU-T Recommendation G.122 [15].
telephony 7 kHz teleservice: A real-time teleservice in which speech (7 kHz or 3,1 kHz bandwidth) can
be interchanged using one circuit-mode 64 kbit/s connection [ETS 300 263, clause 5].
3.2 Abbreviations
For the purposes of this Part of the I-ETS, the following abbreviations apply:
ADPCM Adaptive Differential Pulse Code Modulation
ARL Acoustic Reference Level
ERP Ear Reference Point
HFRP Hands Free Reference Point
HFT Hands Free Terminal
ISDN Integrated Services Digital Network
LE Listener echo loss
LRGP Loudness Rating Guard-ring Position
LST LoudSpeaking Telephony
MRP Mouth Reference Point
PCM Pulse Code Modulation
PSTN Public Switched Telephone Network
RLR Receiving Loudness Rating
SB-ADPCM Sub-Band Adaptive Differential Pulse Code Modulation
S/D Signal-to-Distortion
SLR Sending Loudness Rating
TCL Terminal Coupling Loss
TCLw Weighted Terminal Coupling Loss
TE Terminal Equipment
TEUT Telephone Equipment Under Test
4 D-channel characteristics
The technical requirements for the D-channel signalling characteristics of wideband hands free terminals
shall be those applicable to wideband handset terminals, as specified in I-ETS 300 245-5 [1].
5 In-band signalling characteristics
The technical requirements for the in-band signalling characteristics of wideband hands free terminals
shall be those applicable to wideband handset terminals, as specified in I-ETS 300 245-5 [1].

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I-ETS 300 245-6: January 1996
6 Transmission characteristics
6.1 Relative level
The digital interface shall be a 0 dBr point, according to ITU-T Recommendation G.101 [2].
6.2 Signal encoding
Wideband telephone terminals shall be able to operate both narrow band CCITT Recommendation G.711
[3] Pulse code Modulation (PCM) and wideband CCITT Recommendation G.722 [4] coding. The default
mode for narrow band coding is A-law, however, μ-law coding shall also be implemented.
6.2.1 CCITT Recommendation G.711 encoding
6.2.1.1 A-law
At the beginning of a call operation, mode 0F (CCITT Recommendation G.711 [3]) shall be used. The
default encoding shall be A-law.
When in mode 0U the requirements of I-ETS 300 245-3 [5] shall be met.
6.2.1.2 μμ-law)
If information is available to the terminal, either by configuration or by user input, as to whether the
destination is within a μ-law region, then this encoding law shall be used after the reception of the
ALERTING message or, if the ALERTING message is not received, the CONNECT message, or in-band
signalling, as described in I-ETS 300 245-5 [1] has been initiated. The information shall be encoded using
the μ-law at 64 kbit/s as defined in CCITT Recommendation G.711 [3].
It is the responsibility of the calling terminal to ensure that the correct encoding law is used. If no indication
on the coding law has been received during the D-channel signalling sequence or during the in-band
signalling sequence, the calling terminal shall use the default coding law while monitoring the statistics of
the incoming signal. In order to determine whether the incoming signal was encoded by A-law or μ-law
PCM, the algorithm described in appendix 1 to CCITT Recommendation G.725 [6] (note) shall be used.
Compliance with CCITT Recommendation G.725 [6] algorithm implementation shall be checked by the
test described in annex A, subclause A.2.7.
NOTE: It should be noted that CCITT Recommendation G.725 [6] was cancelled and replaced
by ITU-T Recommendation H.245 at the ITU-T SG 15 meeting held in November
1995.
For terminals also supporting handset operations, conformance to the μ-law coding requirements shall be
checked in the handset mode, as specified in I-ETS 300 245-5 [1].
For terminals not supporting the handset mode, the coding requirements shall be checked by using the
test methods specified in I-ETS 300 245-3 [5], with the following amendments:
- the test signal generator and analyser shall use μ-law encoding/decoding;
- only sensitivity/frequency, loudness rating, harmonic distortion and noise requirements
shall be verified;
- the sending noise shall meet the requirement described in ITU-T Recommendation P.31
[7], clause 4.
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I-ETS 300 245-6: January 1996
6.2.2 CCITT Recommendation G.722 encoding
When operating in modes 1, 2 or 3 the signal shall be encoded as specified in CCITT Recommendation
G.722 [4].
The lower sub-band shall be encoded using 6 bits independent of operation mode. When operating in
modes 2 or 3 the least significant bit or the two least significant bits shall be used for the auxiliary data
channel, see CCITT Recommendation G.722 [4], subclause 1.3.
6.3 Signal decoding
6.3.1 CCITT Recommendation G.711 decoding
6.3.1.1 A-law
At the beginning of a call, the operating mode 0F (CCITT Recommendation G.711 [3]) shall be used. The
default decoding law shall be A-law.
When in mode 0U, the requirements of I-ETS 300 245-3 [5] shall be met.
6.3.1.2 μμ-law)
When a terminal has detected, by D-channel signalling, in-band signalling or by other means that the
incoming bit stream is μ-law encoded, the decoding algorithm shall fulfil the characteristics described in
CCITT Recommendation G.711 [3].
For terminals also supporting handset operations the conformance to the μ-law decoding requirements
shall be checked in the handset mode as specified in I-ETS 300 245-5 [1]. For terminals not supporting
the handset mode the coding requirements shall be checked by using the test methods specified in
I-ETS 300 245-3 [5], with the amendments specified in subclause 6.2.1.2 above.
6.3.2 CCITT Recommendation G.722 decoding
The requirements specified in I-ETS 300 245-5 [1] for wideband handset terminals with respect to the
operating mode selection and to fallback procedures to 3,1 kHz telephony and to Public Switched
Telephone Network (PSTN) shall apply to wideband hands free operations.
6.4 Speech transmission characteristics
6.4.1 Volume control
Unless stated otherwise, the compliance requirements are intended as referred to the maximum position
of the receiving volume control (when manually operated).
The minimum range of the receiving volume control (when manually operated) shall be 15 dB.
The operation of the volume control shall not affect the sending sensitivity. No user accessible control
shall be available for modifying the sending sensitivity, apart from the "muting" of the hands free
microphone.
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I-ETS 300 245-6: January 1996
6.4.2 Requirements applicable to Hands Free Terminal and LoudSpeaking Telephony
Table 1 specifies the applicability of speech transmission requirements to hands free and loudspeaking
functions.
Table 1: Applicability of speech transmission requirements to hands free and loudspeaking
functions
HFT LST
Sensitivity-frequency response
Sending x
Receiving x x
Loudness Rating
Sending x
Receiving x x
Terminal Coupling Loss
Weighted Terminal xx
Coupling Loss (TCLw)
Stability Loss x x
Harmonic Distortion
Sending x
Receiving x x
Out of Band Signals
Sending x
Receiving x x
Noise
Sending x
Receiving x x
Delay x
6.4.3 Sensitivity-frequency response
6.4.3.1 Sending
The sending sensitivity-frequency response (from Mouth Reference Point (MRP) to digital interface) shall
fall within the mask specified in table 2.
The mask ordinates are in relative dB units; compliance shall be checked by vertically shifting the mask
with respect to the sending characteristic of the terminal under test.

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I-ETS 300 245-6: January 1996
Table 2: Sending sensitivity/frequency mask
Centre Frequency Upper limit Lower limit
[Hz] [dB] [dB]
100 4 -
125 4 - 7
160 4 - 5,5
200 4 - 4
250 4 - 4
315 4 - 4
400 4 - 4
500 4 - 4
630 4 - 4
800 4 - 4
1 000 4 - 4
1 250 4,6 - 4
1 600 5,2 - 4
2 000 5,9 - 4
2 500 6,5 - 4
3 150 7,1 - 4
4 000 7,7 - 4
5 000 8,4 - 4
6 300 9 - 7
8 000 9 -
NOTE: Under ideal conditions, the speech quality can be improved
by transmitting frequencies lower than 125 Hz. However,
under normal operation conditions, extending the frequency
range to lower frequencies can cause excessive
transmission of unwanted noise. Furthermore, a rising
sensitivity-frequency response is recommended.
Compliance shall be checked by the tests described in annex A, subclause A.2.1.1.
6.4.3.2 Receiving
The receiving sensitivity-frequency response (from the digital interface to the measurement point C) shall
fall within the mask specified in table 3.
The mask ordinates are in relative dB units; compliance shall be checked by vertically shifting the mask
with respect to the receiving characteristic of the terminal under test.

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I-ETS 300 245-6: January 1996
Table 3: Receiving sensitivity/frequency mask
Centre Frequency Upper limit Lower limit
[Hz] [dB] [dB]
100 8 -
125 8 -
160 8 - 15
200 8 - 9
250 8 - 6
315 7 - 6
400 6 - 6
500 6 - 6
630 6 - 6
800 6 - 6
1 000 6 - 6
1 250 6 - 6
1 600 6 - 6
2 000 6 - 6
2 500 6 - 6
3 150 6 - 6
4 000 6 - 6
5 000 6 - 6
6 300 6 - 9
8 000 6 -
Compliance shall be checked by the tests described in annex A, subclause A.2.1.2.
6.4.4 Loudness rating
6.4.4.1 Sending Loudness Rating
The nominal value of SLR shall be:
SLR = + 12 dB
A manufacturing tolerance of ± 3 dB is allowed.
Compliance shall be checked by measurement of the SLR as described in annex A, subclause A.2.2.1.
6.4.4.2 Receiving Loudness Rating
The nominal value of RLR shall be:
RLR = + 6 dB
A manufacturing tolerance of ± 3 dB is allowed.
The RLR
measured with the manual volume control at the maximum position shall be:
min
RLR = - 4 dB
min
A manufacturing tolerance of ± 3 dB is allowed.
The RLR measured with the volume control at its minimum position shall be by 15 dB to 30 dB quieter
(higher) than RLR .
min
The nominal value of RLR shall be met (within its tolerance) for at least one setting of the volume control
(when manually operated).
For sets only equipped with automatic (receiving) gain control, the RLR measured with an input signal of
- 15 dBm0 shall be higher by 10 dB to 15 dB than the RLR measured with an input signal of - 30 dBm0.

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I-ETS 300 245-6: January 1996
The nominal RLR shall be included in the measured range. The RLR measured with an input signal of
- 30 dBm0 shall be:
RLR (@-30 dBm0) = - 4 dB.
A manufacturing tolerance of ± 3 dB is allowed.
Compliance shall be checked b
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