ETSI I-ETS 300 281 ed.1 (1994-05)

Integrated Services Digital Network (ISDN); Telephony 7 kHz teleservice; Terminal requirements necessary for end-to-end compatibility

T/TE 12-06A

Digitalno omrežje z integriranimi storitvami (ISDN) – Daljinske storitve: telefonija 7 kHz – Terminalske zahteve, potrebne za zagotavljanje združljivosti terminalov v zvezi konec-konec

General Information

• Status: Published
• Publication Date: 19-May-1994
• Technical Committee: TE 4 - Audiovisual and Voice Terminals
• Current Stage: 12 - Completion
• Due Date: 23-May-1994
• Completion Date: 20-May-1994
• Ref Project: SIST I-ETS 300 281 E1:2003 - Integrated Services Digital Network (ISDN); Telephony 7 kHz teleservice; Terminal requirements necessary for end-to-end compatibility

Standards Content (Sample)

SLOVENSKI STANDARD
01-december-2003
Digitalno omrežje z integriranimi storitvami (ISDN) – Daljinske storitve: telefonija 7
kHz – Terminalske zahteve, potrebne za zagotavljanje združljivosti terminalov v
zvezi konec-konec
Integrated Services Digital Network (ISDN); Telephony 7 kHz teleservice; Terminal
requirements necessary for end-to-end compatibility
Ta slovenski standard je istoveten z: I-ETS 300 281 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 300 281
TELECOMMUNICATION May 1994
STANDARD
Source: ETSI TC-TE Reference: T/TE 12-06 (A)
ICS: 33.080
ISDN, telephony 7kHz teleservice
Key words:
Integrated Services Digital Network (ISDN);
Telephony 7 kHz teleservice
Terminal requirements necessary for end-to-end compatibility
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 1994. All rights reserved.
New presentation - see History box

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I-ETS 300 281: May 1994
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 300 281: May 1994
Contents
Foreword .7
Introduction.7
1 Scope .9
2 Normative references .9
3 Definitions and symbols .11
3.1 Teleservices.11
3.2 Modes of operation .11
3.3 Terminal types .11
3.4 Acoustic Reference Level (ARL).11
3.5 Weighted Terminal Coupling Loss (TCLw).11
4 Abbreviations.12
5 D-channel characteristics.12
5.1 General .12
5.2 Outgoing calls .12
5.3 Incoming calls .13
5.3.1 Telephony 7 kHz call request .13
5.3.2 Telephony 3,1 kHz call request .13
5.4 Support of supplementary services .13
5.4.1 Terminal selection using MSN or SUB.13
5.4.2 Inband signalling when invoking supplementary services.13
5.5 Interim procedures.14
5.5.1 General.14
5.5.2 Outgoing calls.14
5.5.3 Incoming calls.14
5.6 Call clearing .14
6 B-channel characteristics .15
6.1 Relative level.15
6.2 Signal encoding .15
6.2.1 CCITT Recommendation G.711.15
6.2.1.1 A-law.15
6.2.1.2 μ-law .15
6.2.2 CCITT Recommendation G.722 encoding.15
6.3 Signal decoding .16
6.3.1 CCITT Recommendation G.711.16
6.3.1.1 A-law.16
6.3.1.2 μ-law .16
6.3.2 CCITT Recommendation G.722.16
6.3.2.1 General.16
6.3.2.2 Mode 1.16
6.3.2.3 Mode 2.16
6.3.2.4 Mode 3.16
6.3.2.5 Fallback to the telephony 3,1 kHz teleservice .16
6.3.2.6 Interworking with the Public Switched Telephone Network
(PSTN).17
6.4 Speech transmission characteristics (handset mode).17
6.4.1 Volume control .17
6.4.2 Sensitivity-frequency response.17
6.4.2.1 Sending.17
6.4.2.2 Receiving.17

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6.4.3 Loudness rating . 18
6.4.3.1 Sending Loudness Rating (SLR). 18
6.4.3.2 Receiving Loudness Rating (RLR). 18
6.4.4 Talker sidetone . 19
6.4.5 Terminal Coupling Loss (TCL). 19
6.4.5.1 Weighted Terminal Coupling Loss (TCLw). 19
6.4.5.2 Stability loss . 19
6.4.6 Distortion. 19
6.4.6.1 Sending. 19
6.4.6.2 Receiving . 20
6.4.6.3 Sidetone. 20
6.4.7 Out-of-band signals . 20
6.4.7.1 Discrimination against out-of-band input signals (Sending) 20
6.4.7.2 Spurious out-of-band (Receiving) . 20
6.4.8 Noise. 21
6.4.8.1 Sending. 21
6.4.8.2 Receiving . 21
6.4.9 Acoustic shock. 21
6.4.9.1 Continuous Signal. 21
6.4.9.2 Peak signal. 21
6.4.10 Delay. 21
7 In-band signalling. 22
7.1 Frame structure. 22
7.1.1 General . 22
7.1.2 Frame search . 22
7.1.3 Frame alignment. 22
7.1.4 Multiframe alignment . 22
7.2 Telephony 7 kHz BAS attributes . 22
7.2.1 General . 22
7.2.2 Audio coding command . 22
7.2.3 Audio capability. 23
7.3 Sequences . 24
7.4 Procedures. 24
Annex A (normative): Test methods. 25
A.1 General conditions for testing. 25
A.1.1 Environment for tests . 25
A.1.2 Power supply limitations. 25
A.1.3 Test equipment interface. 25
A.1.4 Test equipment requirements . 25
A.1.4.1 Electro-acoustic equipment . 25
A.1.4.2 Test equipment for the digital interface . 25
A.1.4.2.1 Codec specification. 25
A.1.4.2.2 Analogue interface . 25
A.1.4.2.3 Definition of 0 dBr point. 26
A.1.5 Accuracy of calibrations . 26
A.2 Speech transmission requirements testing. 26
A.2.1 Sensitivity-frequency response . 26
A.2.1.1 Sending. 26
A.2.1.2 Receiving . 27
A.2.2 Loudness rating. 27
A.2.2.1 Sending Loudness Rating. 27
A.2.2.2 Receiving Loudness Rating . 27
A.2.3 Sidetone . 27
A.2.3.1 Talker sidetone . 27
A.2.4 Terminal Coupling Loss (TCL) . 27
A.2.4.1 Weighted Terminal Coupling Loss (TCLw). 27
A.2.4.2 Stability loss. 28
A.2.5 Distortion . 29
A.2.5.1 Sending. 29

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A.2.5.2 Receiving.29
A.2.5.3 Sidetone .29
A.2.6 Out-of-band signals .29
A.2.6.1 Discrimination against out-of-band input signals (sending).29
A.2.6.2 Spurious out-of-band (receiving).30
A.2.7 Noise.30
A.2.7.1 Sending .30
A.2.7.2 Receiving.31
A.2.8 Acoustic shock.31
A.2.8.1 Continuous signal.31
A.2.9 Delay.31
Annex B (informative): Bibliography.33
History.34

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Foreword
This Interim European Telecommunication Standard (I-ETS) was produced by the Terminal Equipment
(TE) Technical Committee of the European Telecommunications Standards Institute (ETSI).
An ETSI 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 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 I-ETS contains two annexes. Annex A is normative to this I-ETS whereas Annex B is informative.
Introduction
This I-ETS presents the requirements necessary for compatibility between handset terminals supporting
the telephony 7 kHz teleservice in the ISDN. It covers the following aspects:
1) D-Channel signalling;
2) Inband signalling;
3) Speech transmission characteristics.
The D-Channel and inband signalling procedures are based on existing standards, and references are
made to these.
A 7 kHz bandwidth handset usually requires the use of low acoustic impedance receivers. To test these
receivers, a type 3.2 artificial ear as specified in ITU-T Recommendation P. 57 is needed. Although this
ear is specified by ITU-TS, no device is commercially available at this time. The requirements presented
are based on test results using prototypes developed by individual test laboratories. The results need to
be checked on a commercially available device to secure reproducibility.
A terminal that supports the telephony 7 kHz teleservice shall also support the telephony 3,1 kHz
teleservice. The end-to-end compatibility requirements for this teleservice can be found in ETS 300 082.
The receive characteristics requirements and test methods of ETS 300 082 are not valid when low
acoustic impedance receivers are used.
There is an urgent need for a standard on the speech transmission characteristics of telephony 7 kHz
terminals. ETSI has, therefore, decided to publish this I-ETS in order to provide manufacturers and test
laboratories with a set of agreed requirements and test procedures based on the state of the art. ETSI will
continue the work on requirements and test methods and the results of this work will be included in a
revised version to be issued when the period of validity of this I-ETS has expired. Findings and comments
to this I-ETS are welcomed and should be sent to ETSI at the address indicated on the title page.
In the present version, no requirements to Listener Sidetone Rating (LSTR) have been included because
the test methods require further study. The users of this I-ETS should note that requirements to all
characteristics where the receiver is included may be altered when more experience has been gained.

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I-ETS 300 281: May 1994
1 Scope
This I-ETS specifies technical characteristics (logical and electroacoustic) that are necessary to provide
end-to-end compatibility of terminal equipment that support the telephony 7 kHz teleservice as defined in
ETS 300 263 [1] which is intended for connection to the basic rate interface at the coincident S and T
reference point or S reference point of the pan-European Integrated Services Digital Network (ISDN), as
provided by European public telecommunications operators.
The requirements of this I-ETS are in addition to those of standards for connection to the ISDN basic rate
interface.
The requirements of this I-ETS describe the logical characteristics of the user-network signalling and
inband signalling relevant to this teleservice.
The requirements of this I-ETS provide real time two-way speech communication of an improved quality
when compared with the telephony 3,1 kHz teleservice.
The speech transmission requirements of this I-ETS define only those characteristics relevant to
telephony terminals equipped with a handset.
This I-ETS is applicable to terminal equipment, and other equipment (e.g. interworking units, conference
bridges), equipped with a handset and supporting the telephony 7 kHz teleservice.
In this I-ETS, the speech transmission requirements are not applicable to:
a) handsfree or loudspeaking telephony;
b) telephony for disabled people (e.g. with amplification of received speech as an aid for the hard of
hearing);
c) telephony in hostile environments.
NOTE 1: The characteristics of the ISDN user-network interface are specified in ETS 300 012
[2] and ETS 300 102-1 [3].
NOTE 2: Information about type approval specifications for attachment to the ISDN basic
access, and for terminals supporting the telephony 3,1 kHz teleservice in the ISDN can
be found in Annex B.
NOTE 3: The telephony 7 kHz teleservice as defined in ETS 300 263 [1] does not include a data
communication facility. The inband signalling codes for such a facility are, therefore,
not a part of this I-ETS. Relevant information can be found in ETS 300 144 [4] and
ETS 300 143 [5].
2 Normative references
This I-ETS incorporates by dated or undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications 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] ETS 300 263 (1994): "Integrated Services Digital Network (ISDN); Telephony 7
kHz teleservice, Service description".
[2] ETS 300 012 (1992): "Integrated Services Digital Network (ISDN); Basic user-
network interface, Layer 1 specification and test principles".
[3] ETS 300 102-1 (1990): "Integrated Services Digital Network (ISDN); User-
network interface layer 3, Specifications for basic control".

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I-ETS 300 281: May 1994
[4] ETS 300 144: "Integrated Services Digital Network (ISDN); Audiovisual
Services, Frame structure for a 64 to 1 920 kbit/s channel and associated syntax
for inband signalling".
[5] ETS 300 143: "Integrated Services Digital Network (ISDN); Audiovisual
Services, Inband signalling procedures for audiovisual terminals using digital
channels up to 2 048 kbit/s".
[6] CCITT Recommendation G.701 (1988): "Vocabulary of digital transmission and
multiplexing, and pulse code modulation (PCM) terms".
[7] CCITT Recommendation I.112 (1988): "Vocabulary of terms for ISDNs".
[8] CCITT Recommendation I.230 (1988): "Definition of bearer service categories".
[9] CCITT Recommendation I.240 (1988): "Definition of teleservices".
[10] ITU-T Recommendation P.10 (1993): "Vocabulary of terms on telephone
transmission quality and telephone sets".
[11] ITU-T Recommendation P.51 (1993): "Artificial mouth".
[12] ITU-T Recommendation P.57 (1993): "Artificial ears".
[13] ETS 300 111 (1992): "Integrated Services Digital Network (ISDN); Telephony
3,1 kHz teleservice, Service description".
[14] CCITT Recommendation G.711 (1988): "Pulse Code Modulation (PCM) of voice
frequencies".
[15] CCITT Recommendation G.722 (1988): "7 kHz audio coding within 64 kbit/s".
[16] Draft prETS 300 267 (1993): "Integrated Services Digital Network (ISDN);
Telephony 7 kHz and videotelephony teleservices, Digital Subscriber Signalling
System No. one (DSS1) protocol".
[17] prI-ETS 300 322: Integrated Services Digital Network (ISDN); Digital Subscriber
Signalling System No. one (DSS1), Abstract Test Suite (ATS) for use of
signalling-network-layer protocol for circuit-mode basic call control".
[18] CCITT Recommendation G.101 (1988): "The transmission plan".
[19] CCITT Recommendation G.725 (1988): "System aspects for the use of the 7
kHz audio codec within 64 kbit/s".
[20] ETS 300 082 (1992): "Integrated Services Digital Network (ISDN); 3,1 kHz
telephony teleservice, End-to-end compatibility".
[21] ITU-T Recommendation P.31 (1993): "Transmission characteristics for digital
telephones".
[22] ITU-T Recommendation P.79 (1993): "Calculation of loudness ratings".
[23] ISO 3 (1973): "Preferred numbers - series of preferred numbers".
[24] ITU-T Recommendation P.64 (1993): "Determination of sensitivity/frequency
characteristics of local telephone systems to permit calculation of their loudness
ratings".
[25] IEC Publication 651: "Sound level meters".

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I-ETS 300 281: May 1994
[26] CCITT Recommendation G.122 (1988): "Influence of national systems on
stability, talker echo, and listener echo in international connections".
3 Definitions and symbols
For the purposes of this I-ETS, the relevant definitions and symbols used in ETS 300 143 [5], ETS 300
144 [4], CCITT Recommendations G.701 [6], I.112 [7], I.230 [8], I.240 [9], and ITU-T Recommendations
P.10 [10], P.51 [11] and P.57 [12] apply with the following.
3.1 Teleservices
Telephony 3,1 kHz: A description of the telephony 3,1 kHz teleservice can be found in ETS 300 111 [13].
Telephony 7 kHz: A description of the telephony 7 kHz teleservice can be found in ETS 300 263 [1].
3.2 Modes of operation
The following modes of operation are defined:
Mode 0U: 64 kbit/s 3,1 kHz audio to CCITT Recommendation G.711 [14], unframed.
Mode 0F: 56 kbit/s 3,1 kHz audio to CCITT Recommendation G.711 [14] truncated to 7 bits,
framed.
Mode 1: 64 kbit/s 7 kHz audio to CCITT Recommendation G.722 [15].
Mode 2: 56 kbit/s 7 kHz audio to CCITT Recommendation G.722 [15] and up to 6,4 kbit/s data.
Mode 3: 48 kbit/s 7 kHz audio to CCITT Recommendation G. 722 [15] 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.
3.3 Terminal types
Three types of terminals are defined. These types are:
Type 0: a digital telephony terminal working in Mode 0U only.
Type 1: a telephony 7 kHz terminal capable of working in Modes 0U, 0F, 1 and 2. In Modes 0U
and 0F, both A-law and μ-law coding shall be implemented.
Type 2: a member of a family of telephony 7 kHz/data terminals capable of working at least in
Modes 0U, 0F, 1, 2 and 3. In Modes 0U and 0F, both A-law and μ-law coding shall be
implemented.
The Type 1 terminal supports the G.722-64 audio capability as defined in ETS 300 144 [4]. In order to
establish framing the terminal shall be able to transmit and receive audio encoded according to CCITT
Recommendation G.722 [15] at 56 kbit/s.
The type 2 terminal supports the G.722-48 audio capability as defined in ETS 300 144 [4].
3.4 Acoustic Reference Level (ARL)
The acoustic level which gives -10 dBm0 at the digital interface.
3.5 Weighted Terminal Coupling Loss (TCLw)
The TCLw, using the calculation procedure as given in Annex A to this I-ETS.

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4 Abbreviations
For the purposes of this I-ETS, the following abbreviations apply:
ARL Acoustic Reference Level
BAS Bit-rate Allocation Signal
CONF Conference Call, Add-on
DRP Eardrum Reference Point
ECT Explicit Call Transfer
ERP Ear Reference Point
HLC High Layer Compatibility
HOLD Call Hold
ISDN Integrated Services Digital Network
Lmest Sidetone path loss
LRGP Loudness Rating Guard Ring Position
LSTR Listener Sidetone Rating
MRP Mouth Reference Point
MSN Multiple Subscriber Number
PSTN Public Switched Telephone Network
RLR Receiving Loudness Rating
r.m.s root mean square
SB-ADPCM Sub-Band Adaptive Differential Pulse Code Modulation
SLR Sending Loudness Rating
STMR Sidetone Masking Rating
SUB Subaddressing
TCL Terminal Coupling Loss
TCLw Weighted Terminal Coupling Loss
TP Terminal Portability
UDI Unrestricted Digital Information
UDI-TA Unrestricted Digital Information with Tones and Announcements
3PTY Three Party
5 D-channel characteristics
5.1 General
This Clause describes the relation between the outband D-channel procedures and the inband B-channel
procedures for terminals to support the telephony 7 kHz teleservice and the interim procedures for
terminals connected to networks where the telephony 7 kHz teleservice, according to ETS 300 267 [16], is
not yet implemented.
ETS 300 267 [16] specifies the stage 3 description of the telephony 7 kHz teleservice at the T reference
point or the coincident S and T reference point by means of the Digital Subscriber Signalling System No.
one (DSS1) protocol.
NOTE: ETR 018 gives further guidance for the codepoints to be used for the Bearer capability
and High layer compatibility information element when setting up a telephony 7 kHz
teleservice call.
ETS 300 267 [16] makes use of the requirements contained within ETS 300 102-1 [3] which specifies the
D-channel signalling of the basic call procedures.
Conformance test requirements for the basic call are specified in prI-ETS 300 322 [17].
Conformance test requirements for the procedures in ETS 300 267 [16] are not yet published.
5.2 Outgoing calls
When initiating an outgoing call on the telephony 7 kHz teleservice a fallback procedure to the telephony
3,1 kHz teleservice shall be available (fallback allowed).

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I-ETS 300 281: May 1994
NOTE: When this option is used, the network will reserve any required echo cancellation
devices, A-law to μ-law convertors, etc., in case a speech information transfer
capability is used for the resultant connection.
It shall be possible to disable the fallback procedure (fallback not allowed).
The signalling procedures for fallback and fallback not allowed are specified in ETS 300 267 [16].
When the connection is established and from the messages received from the network it can be derived
that the resultant service is:
a) the telephony 7 kHz teleservice, then inband signalling procedures as described in Clause 7 shall
be initiated;
b) the telephony 3,1 kHz teleservice or the 3,1 kHz audio bearer service, then the terminal shall start
transmitting in mode 0U (CCITT Recommendation G.711 [14]), using A-law coding.
5.3 Incoming calls
5.3.1 Telephony 7 kHz call request
When after successfully performing D-channel checks, according to ETS 300 267 [16], the connection has
been established and it is known that the resultant service is the telephony 7 kHz teleservice, then the
inband signalling procedures as described in Clause 7 shall be initiated.
5.3.2 Telephony 3,1 kHz call request
When, after successfully performing D-channel checks according to ETS 300 267 [16], the connection has
been established and it is known that the resultant service is the telephony 3,1 kHz teleservice or the 3,1
kHz audio bearer service, then the terminal shall start transmitting in mode 0U, PCM A-law, without
initiating inband signalling procedures.
5.4 Support of supplementary services
5.4.1 Terminal selection using MSN or SUB
Procedures for terminal selection are outside the scope of this I-ETS.
NOTE: A specification of terminal selection procedures for ISDN telephony terminals can be
found in I-ETS 300 245 Part 1.
5.4.2 Inband signalling when invoking supplementary services
To ensure compatibility the Mode 0 forcing procedure, as described in ETS 300 143 [5], subclause 7.3,
shall be performed before invoking the supplementary services:
- Call Hold (HOLD);
- Explicit Call Transfer (ECT);
- Terminal Portability (TP);
- Three Party (3PTY);
- Conference Call, Add-on (CONF).
The terminal shall be forced to mode 0U, A-law.

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5.5 Interim procedures
5.5.1 General
The information Transfer Capability "Unrestricted Digital Information with Tones and Announcements"
(UDI-TA) and the fallback procedure (use of two Bearer capability and High layer compatibility information
elements in a SETUP message) need not be implemented in all European and non-European ISDNs. As
an interim solution, terminals complying with this I-ETS may, as an option, in addition to the requirements
described in ETS 300 267 [16], meet the requirements described in the following subclauses.
Procedures for the activation and deactivation of these characteristics shall be available.
NOTE: For the interim solution, when using the circuit mode 64 kbit/s unrestricted 8 kHz
structured bearer service category, different terminals (e.g. terminals supporting the
telephony 7 kHz teleservice, the videotelephony teleservice and data services)
attached to a basic access in a multipoint configuration cannot be individually selected
by Bearer capability information elements. In addition, the use of High layer
compatibility information element may not be supported by all networks. Therefore, it is
sometimes necessary for the user to apply other addressing mechanisms like the
Multiple Subscriber Number (MSN) or Subaddressing (SUB) supplementary service.
5.5.2 Outgoing calls
When initiating an outgoing call, instead of requesting the telephony 7 kHz teleservice the user may
request the circuit mode 64 kbit/s unrestricted 8 kHz structured bearer service category. The coding of the
Bearer capability information element for this service is described in ETS 300 102-1 [3]. The user
information layer 1 protocol field shall be encoded "Recommendation H.221 and H.242". When this
information element is used, no High layer compatibility information element shall be included in the
SETUP message.
NOTE: When the circuit mode 64 kbit/s unrestricted 8 kHz structured bearer service category
is used, the network will provide no tones or announcements in the B-channel.
Information on a harmonized set of information tones locally generated on the basis of
information received in the D-channel can be found in I-ETS 300 245, Part 7.
On receipt of a CONNECT message from the network, the terminal shall move to state U10 and shall
initiate inband signalling procedures as described in Clause 7.
5.5.3 Incoming calls
An incoming call shall be considered as a request for the telephony 7 kHz teleservice if a Bearer capability
information element indicating "UDI-TA" and possibly with the user information layer 1 protocol field
encoded as "Recommendation H.221 and H.242" is included in the SETUP message.
NOTE: When the incoming SETUP message contains only a Bearer capability information
element with no user information layer 1 protocol field encoded as "Recommendation
H.221 and H.242", it is not possible to determine the requested service. Then, after
connecting to the call, the inband signalling procedures will determine the teleservice.
Inband signalling procedures as described in Clause 7 shall be initiated when the D-channel compatibility
checks are considered successful and the CONNECT ACKNOWLEDGE message has been received
from the network.
5.6 Call clearing
Before call clearing according to ETS 300 102-1 [3] is initiated by either terminal, the clearing terminal
shall transmit the BAS command mode 0U A-law, and switch to this mode. When those procedures are
completed, normal D-channel procedures, as described in ETS 300 102-1 [3], shall be used to clear the
call.
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I-ETS 300 281: May 1994
If a DISCONNECT message which contains a progress indicator #8 is received, the terminal shall switch
to mode 0U, A-law.
6 B-channel characteristics
Throughout Clause 6, in addition to the terminology defined in Clause 3, the definitions of CCITT
Recommendation G.701 [6] and ITU-T Recommendation P.10 [10] apply.
6.1 Relative level
The digital interface is a 0 dBr point according to CCITT Recommendation G.101 [18].
6.2 Signal encoding
6.2.1 CCITT Recommendation G.711
6.2.1.1 A-law
When in mode 0U, the encoding law shall conform to CCITT Recommendation G.711 [14].
At the beginning of a call operation mode 0F (CCITT Recommendation G.711 [14] coding) shall be used.
The default encoding shall be A-law.
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 inband
signalling, as described in Clause 6 has been initiated.
The information shall be encoded using the μ-law at 64 kbit/s as defined in CCITT Recommendation
G.711 [14].
It shall be the responsibility of the calling terminal to ensure that correct encoding law is used. If no
indication on the coding law is available, 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
[19] shall be used.
For handset terminals, conformance to the coding requirements shall be checked by using the
requirements and test methods described in ETS 300 082 [20] with the following amendments:
- the test signal generator and analyzer shall use μ-law encoding/decoding;
- the quantising distortion characteristics shall be verified by using the sinewave method only. The
signal-to-total-distortion ratio shall meet the requirements described in ITU-T Recommendation
P.31 [21], Section 5;
- there is no variation of gain requirement;
- the noise levels (sending and receiving) shall meet the requirements described in ITU-T Recom-
mendation P.31 [21], Section 4.
NOTE: To date there is no standard describing requirements and corresponding test methods
for loudspeaking and handsfree terminals.
6.2.2 CCITT Recommendation G.722 encoding
When operating in Mode 1, 2 or 3 the signal shall be encoded as specified in CCITT Recommendation
G.722 [15], Section 3.
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According to CCITT Recommendation G.722 [15] the lower sub-band shall be encoded using 6 bits
independent of operation mode. However, when operating in Mode 2 or Mode 3, the least significant bit or
the two least significant bits shall be replaced by the bits for the auxiliary data channel, see CCITT
Recommendation G.722 [15], Section 1.3.
6.3 Signal decoding
6.3.1 CCITT Recommendation G.711
6.3.1.1 A-law
When in mode 0U, the decoding law shall conform to CCITT Recommendation G.711 [14].
At the beginning of a call operation mode 0F (CCITT Recommendation G.711 [14] coding) shall be used.
The default decoding shall be A-law.
6.3.1.2 μ-law
When a terminal by D-channel signalling, inband signalling or by other means has detected that the
incoming bitstream is encoded using the μ-law algorithm, the decoding algorithm shall fulfil the
characteristics described in CCITT Recommendation G.711 [14].
Conformance shall be checked by using the test methods described in ETS 300 082 [20], modified as
described in subclause 6.2.1.2.
6.3.2 CCITT Recommendation G.722
6.3.2.1 General
If the called terminal during the call setup phase or during the in-band signalling procedure (cf subclause
6.3), has indicated that it supports the telephony 7 kHz teleservice in the ISDN, operating mode 1, 2 or 3
shall be used according to the result of the initialization procedure.
6.3.2.2 Mode 1
When operating in mode 1, the lower sub-band decoder shall use a 6 bit codeword as described in
CCITT Recommendation G.722 [15]. The signal decoding shall be as described in CCITT Recommend-
ation G.722 [15], Section 4.
6.3.2.3 Mode 2
When operating in mode 2 the lower sub-band decoder shall use a 5 bit codeword as described in CCITT
Recommendation G.722 [15]. The signal decoding shall be as described in CCITT Recommendation
G.722 [15], Section 4.
6.3.2.4 Mode 3
When operating in mode 3, the lower sub-band decoder shall use a 4 bit codeword as described in CCITT
Recommendation G.722 [15]. The signal decoding shall be as described in CCITT Recommendation
G.722 [15], Section 4.
6.3.2.5 Fallback to the telephony 3,1 kHz teleservice
If fallback to the telephony 3,1 kHz teleservice occurs, the calling terminal shall switch to operational
mode 0U, A-law.
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6.3.2.6 Interworking with the Public Switched Telephone Network (PSTN)
If interworking with the PSTN occurs, the calling terminal shall switch to operational mode 0U, A-law.
6.4 Speech transmission characteristics (handset mode)
When the terminal is working in 7 kHz mode (mode 1) the requirements of this subclause shall be met.
When the terminal is working in 3,1 kHz mode (mode 0U) the speech transmission requirements of
ETS 300 082 [20] shall be met. The receive characteristics requirements and test method of ETS 300 082
[2] are not valid when low impedance receivers are implemented in the handset.
The acoustic impedance of the receiver shall be stated by a supplier's declaration.
6.4.1 Volume control
Unless stated otherwise, compliance requirements are intended to be as referred to the maximum position
of the receiving volume control (when available).
The minimum range of the receiving volume control (when provided) shall be 15 dB.
6.4.2 Sensitivity-frequency response
6.4.2.1 Sending
The Sending Sensitivity-Frequency Response (from Mouth Reference Point (MRP) to digital interface)
shall fall within a mask which can be drawn between the points given in table 1. The mask shall be drawn
with straight lines between the breaking points in table 1 on a logarithmic (frequency) - linear (dB
sensitivity) scale.
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.
Table 1: Sending sensitivity/frequency mask
Centre Upper limit Lower limit
frequency (Hz) (dB) (dB)
100 4
125 - 7
- 4
1 000 4
5 000 - 4
6 300 9 - 7
8 000 9
NOTE: Under ideal conditions, 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.
Conformance shall be checked by the tests described in Annex A, subclause A.2.1.1 of this I-ETS.
6.4.2.2 Receiving
The Receiving Sensitivity-Frequency Response (from the digital interface to the Ear Reference Point
(ERP)) shall fall within a mask which can be drawn between the points given in table 2. The mask shall be

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drawn with straight lines between the breaking points in table 2 on a logarithmic (frequency) - linear (dB
sensitivity) scale.
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.
Table 2: Receiving sensitivity/frequency mask
Centre Upper limit Lower limit
Frequency (Hz) (dB) (dB)
100 4
160 - 7
200 - 4
5 000 - 4
6 300 - 7
8 000 4
Conformance shall be checked by the tests described in Annex A, subclause A.2.1.2 of this I-ETS.
6.4.3 Loudness rating
6.4.3.1 Sending Loudness Rating (SLR)
The nominal value of (narrow band) SLR is:
SLR = 7 dB
A manufacturing tolerance of ± 3 dB is allowed.
Conformance shall be checked by measurement of the SLR as described in Annex A, subclause A.2.2.1
of this I-ETS.
6.4.3.2 Receiving Loudness Rating (
...