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InfoMagic Standards 1994 January
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InfoMagic Standards - January 1994.iso
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1988
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6_8_01.tro
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.rs
.\" Troff code generated by TPS Convert from ITU Original Files
.\" Not Copyright ( c) 1991
.\"
.\" Assumes tbl, eqn, MS macros, and lots of luck.
.TA 1c 2c 3c 4c 5c 6c 7c 8c
.ds CH
.ds CF
.EQ
delim @@
.EN
.nr LL 40.5P
.nr ll 40.5P
.nr HM 3P
.nr FM 6P
.nr PO 4P
.nr PD 9p
.po 4P
.rs
\v | 5i'
.sp 1P
.ce 1000
\v'12P'
\s12FASCICLE\ VI.8
\v'4P'
.RT
.ce 0
.sp 1P
.ce 1000
\fBRecommendations Q.721 to Q.766\fR \v'2P'
.ce 0
.sp 1P
.ce 1000
\fBSPECIFICATIONS\ OF\ SIGNALLING\ SYSTEM\ No.\ 7\fR
.ce 0
.sp 1P
.ce 1000
\fB\ \ \fR \s8\fB | fR \s12\fB\ \ \fR
.RT
.ce 0
.sp 1P
.LP
.rs
.sp 28P
.ad r
Blanc
.ad b
.RT
.LP
.bp
.LP
\fBMONTAGE: PAGE 2 = PAGE BLANCHE\fR
.sp 1P
.RT
.LP
.EF '% Fascicle\ VI.8\ \(em\ Rec.\ Q.721''
.OF '''Fascicle\ VI.8\ \(em\ Rec.\ Q.721 %'
.LP
.bp
.sp 1P
.ce 1000
\v'3P'
SECTION\ 1
.ce 0
.sp 1P
.ce 1000
\fBTELEPHONE\ USER\ PART\ (TUP)\fR
.ce 0
.sp 1P
.sp 2P
.LP
\fBRecommendation\ Q.721\fR
.RT
.sp 2P
.ce 1000
\fBFUNCTIONAL\ DESCRIPTION\ OF\ THE\ SIGNALLING\ SYSTEM\ No.\ 7\fR
.EF '% Fascicle\ VI.8\ \(em\ Rec.\ Q.721''
.OF '''Fascicle\ VI.8\ \(em\ Rec.\ Q.721 %'
.ce 0
.sp 1P
.ce 1000
\fBTELEPHONE\ USER\ PART\ (TUP)\fR
.ce 0
.sp 1P
.LP
\fB1\fR \fBGeneral\fR
.sp 1P
.RT
.PP
Use of Signalling System No.\ 7 for telephone call control
signalling requires:
.RT
.LP
\(em
application of \fITelephone User Part\fR | (TUP) functions, in
combination with
.LP
\(em
application of an appropriate set of \fIMessage Transfer\fR
\fIPart\fR | (MTP) functions.
.PP
A general description of the signalling system and the division
of functions between the Message Transfer Part and the Telephone User Part
are presented in Recommendation\ Q.700 and the requirements of interaction
between those two parts are contained in Recommendation\ Q.701.
.sp 2P
.LP
\fB2\fR \fBTelephone User Part\fR
.sp 1P
.RT
.PP
The Telephone User Part specified in these specifications defines the necessary
telephone signalling functions for use of Signalling System No.\ 7 for
international telephone call control signalling. It is specified with the
aim of providing the same features for telephone signalling as other CCITT
telephone signalling systems.
.PP
Signalling System No.\ 7 can be used to control the switching of all
types of international circuits to be used in a worldwide connection,
including circuits with speech interpolation and satellite circuits.
.PP
The system meets all requirements defined by the CCITT concerning the service
features for worldwide international semiautomatic and automatic
telephone traffic. It is designed for the bothway operation of speech
circuits.
.PP
When used with homogeneous digital telephone circuits the continuity of
these circuits is ensured by the means for transmission quality supervision
and failure detection that are inherent in the digital systems providing
these circuits. However, the system includes means for link\(hyby\(hylink
assurance of
continuity check of the speech path when used with analogue telephone
circuits and/or digital circuits including certain types of equipment, where
fault indications are lost, e.g.,\ circuit multiplication equipment.
.PP
The signalling system is suitable for national telephone applications.
Most telephone signalling message types and signals specified for
international use are also required in typical national applications. In
addition to these, national applications typically require additional
signalling message types and signals; the system provides ample spare capacity
for such additions.
.PP
The standard label structure specified for telephone signalling
messages requires that all exchanges using the signalling system are
allocated codes from code plans established for the purpose of unambiguous
identification of signalling points. The principles to apply to the
international signalling network are specified in
Recommendation\ Q.708.
.bp
.RT
.sp 2P
.LP
\fB3\fR \fBMessage Transfer Part\fR
.sp 1P
.RT
.PP
The Message Transfer Part of Signalling System No.\ 7 is specified in Recommendations\
Q.701 to\ Q.709. An overview description of the Message
Transfer Part is contained in Recommendation\ Q.701.
.PP
The Message Transfer Part defines a range of functions by which
different signalling modes and different signalling network configurations
may be realized. Any application of Signalling System No.\ 7 requires that
an
appropriate selection of these functions is applied depending on the intended
use of the system and the characteristics of the telecommunications network
concerned.
.RT
.sp 2P
.LP
\fBRecommendation\ Q.722\fR
.RT
.sp 2P
.sp 1P
.ce 1000
\fBGENERAL\ FUNCTION\ OF\ TELEPHONE\ MESSAGES\ AND\ SIGNALS\fR
.EF '% Fascicle\ VI.8\ \(em\ Rec.\ Q.722''
.OF '''Fascicle\ VI.8\ \(em\ Rec.\ Q.722 %'
.ce 0
.sp 1P
.PP
This Recommendation describes the general function of
telephone signalling messages and the telephone signals and other information
components contained in those messages. The requirements relating to the
use of the signalling messages and their signal content are specified in
Recommendations\ Q.723 and\ Q.724.
.sp 1P
.RT
.sp 2P
.LP
\fB1\fR \fBTelephone signalling messages\fR
.sp 1P
.RT
.PP
The definition of formats and codes for telephone messages is based on
a functional grouping as indicated in the following. It is expected that
national application of the signalling system typically will require further
message types in addition to the internationally defined message types
indicated in the following. As a result of the criteria on which the grouping
of message types are based some groups as yet only contain one message
type.
.RT
.sp 1P
.LP
1.1
\fIForward address message group\fR
.sp 9p
.RT
.PP
This message group includes messages sent in the forward direction containing
address information. Signals from \(sc\ 3.3 may be included.
Messages so far specified are as follows.
.RT
.sp 1P
.LP
1.1.1
\fIInitial address message\fR
.sp 9p
.RT
.PP
A type of message sent first in the forward direction at call
set\(hyup. It contains address information and other information relating
to the routing and handling of the call.
.RT
.sp 1P
.LP
1.1.2
\fIInitial address message with additional information\fR
.sp 9p
.RT
.PP
A type of message sent first in the forward direction at call
set\(hyup. It contains address, routing and handling information such as
charging and supplementary services information to be used in the call
set\(hyup
procedures.
.RT
.sp 1P
.LP
1.1.3
\fISubsequent address message\fR
.sp 9p
.RT
.PP
A type of message sent in the forward direction subsequent to the initial
address message and containing further address information.
.RT
.sp 1P
.LP
1.1.4
\fISubsequent address message with one signal\fR
.sp 9p
.RT
.PP
A type of message sent in the forward direction subsequent to the initial
address message or to the subsequent address message and containing
only one address signal.
.RT
.sp 1P
.LP
1.2
\fIForward set\(hyup message group\fR
.sp 9p
.RT
.PP
This message group includes messages sent in the forward direction, subsequent
to address messages containing further information for call set\(hyup.
Signals from \(sc\ 3.3 may be included. Messages so far specified are as
follows.
.bp
.RT
.sp 1P
.LP
1.2.1
\fIGeneral forward set\(hyup information message\fR
.sp 9p
.RT
.PP
A type of message containing information relating to the calling
line or possibly other information required for call set\(hyup. This message is
sent in response to a general request message.
.RT
.sp 1P
.LP
1.2.2
\fIContinuity check message\fR
.sp 9p
.RT
.PP
A type of message containing a continuity signal or a
continuity\(hyfailure signal.
.RT
.sp 1P
.LP
1.3
\fIBackward set\(hyup request message group\fR
.sp 9p
.RT
.PP
This message group includes messages sent in the backward direction requesting
further information for call set\(hyup. Signals from \(sc\ 3.4 may be
included. Messages so far specified are as follows.
.RT
.sp 1P
.LP
1.3.1
\fIGeneral request message\fR
.sp 9p
.RT
.PP
A type of message containing a signal requesting transfer of
information relating to a call, e.g.,\ the identity or the category of the
calling party.
.RT
.sp 1P
.LP
1.4
\fISuccessful backward set\(hyup information message group\fR
.sp 9p
.RT
.PP
This message group includes messages sent in the backward direction containing
information relating to a successful call set\(hyup. Signals from
\(sc\ 3.4 may be included. Messages so far specified are as follows.
.RT
.sp 1P
.LP
1.4.1
\fIAddress\(hycomplete message\fR
.sp 9p
.RT
.PP
A type of message containing a signal indicating that all address signals
required for routing the call to the called party have been received
and giving additional information relating to this.
.RT
.sp 1P
.LP
1.4.2
\fICharging message\fR
.sp 9p
.RT
.PP
A type of message containing charging information.
.RT
.sp 1P
.LP
1.5
\fIUnsuccessful backward set\(hyup information message group\fR
.sp 9p
.RT
.PP
This message group includes messages sent in the backward direction containing
information relating to an unsuccessful call set\(hyup. Signals from
\(sc\ 3.4 may be included. Messages so far specified are as follows.
.RT
.sp 1P
.LP
1.5.1
\fISimple unsuccessful backward set\(hyup information message\fR
.sp 9p
.RT
.PP
A message containing a signal from \(sc\ 3.4, relating to an
unsuccessful call set up.
.RT
.sp 1P
.LP
1.5.2
\fIExtended unsuccessful backward set\(hyup information message\fR
.sp 9p
.RT
.PP
A message containing a signal from \(sc\ 3.4, relating to an
unsuccessful call set up, and additional information.
.RT
.sp 1P
.LP
1.6
\fICall supervision message group\fR
.sp 9p
.RT
.PP
This message group includes messages sent in the forward or
backward direction, relating to the supervision of the call. Signals from
\(sc\ 3.5 are included.
.RT
.sp 1P
.LP
1.7
\fICircuit supervision message group\fR
.sp 9p
.RT
.PP
This message group includes messages sent in the forward and
backward direction, relating to the supervision of the circuit. Signals from
\(sc\ 3.6 are included.
.RT
.sp 1P
.LP
1.8
\fICircuit group supervision message group\fR
.sp 9p
.RT
.PP
This message group contains messages from \(sc\ 3.7, relating to the
supervision of circuit groups.
.bp
.RT
.sp 1P
.LP
1.9
\fICircuit network management message group\fR
.sp 9p
.RT
.PP
This message group includes network management messages sent in the backward
direction, which are used to control traffic flow to reduce exchange switching
congestion. Messages so far specified are as follows.
.RT
.sp 1P
.LP
1.9.1
\fIAutomatic congestion control information message\fR
.sp 9p
.RT
.PP
A type of message containing information relating to the congestion status
of the exchange. Signals from \(sc\ 3.8 are included.
.RT
.sp 2P
.LP
\fB2\fR \fBService information\fR
.sp 1P
.RT
.PP
The service information provides the highest level of discrimination between
different sets of signalling messages. It contains the following
components. (See also Note.)
.RT
.sp 1P
.LP
2.1
\fIService indicator\fR
.sp 9p
.RT
.PP
Information used to identify the User Part to which the signalling message
belongs.
.RT
.sp 1P
.LP
2.2
\fINetwork indicator\fR
.sp 9p
.RT
.PP
Information used for discrimination between international and
national messages. In case of national messages, it may for example also be
used for discrimination between different label alternatives for national
use.
.PP
\fINote\fR \ \(em\ The service information octet and the label are not
included in messages transferred between the telephone user part and the
signalling connection control part (e.g.,\ node to node messages).
.RT
.sp 2P
.LP
\fB3\fR \fBSignalling information\fR
.sp 1P
.RT
.sp 1P
.LP
3.1
\fILabel components\fR
.sp 9p
.RT
.PP
In the case of the telephone signalling messages, the label is used for
message routing and, in general, identification of the concerned telephone
circuit. The standard label structure consists of the following
components.
.RT
.sp 1P
.LP
3.1.1
\fIDestination point code\fR
.sp 9p
.RT
.PP
Information identifying the signalling point to which the message is to
be routed.
.RT
.sp 1P
.LP
3.1.2
\fIOriginating point code\fR
.sp 9p
.RT
.PP
Information identifying the signalling point from which the message has
been originated.
.RT
.sp 1P
.LP
3.1.3
\fICircuit identification code\fR
.sp 9p
.RT
.PP
Information identifying the telephone circuit among those
interconnecting the destination point and originating point.
.RT
.sp 2P
.LP
3.2
\fIMessage format identifiers\fR
.sp 1P
.RT
.sp 1P
.LP
3.2.1
\fIHeading\fR
.sp 9p
.RT
.PP
Information discriminating, as applicable, between different groups or
individual types of messages within the set of messages identified by the
service information. The heading is split into two levels. The first level
discriminates between different groups. The second level either discriminates
between different message types or contains a signal.
.bp
.RT
.sp 1P
.LP
3.2.2
\fIField length indicator\fR
.sp 9p
.RT
.PP
Information associated with and indicating the length of a variable length
field.
.RT
.sp 1P
.LP
3.2.3
\fIField indicator\fR
.sp 9p
.RT
.PP
Information associated with and indicating the presence or absence of an
optional field.
.RT
.sp 2P
.LP
3.3
\fIForward set\(hyup telephone signals\fR
.sp 1P
.RT
.sp 1P
.LP
3.3.1
\fIAddress signal\fR
.sp 9p
.RT
.PP
A call set\(hyup signal sent in the forward direction containing one element
of information (digit\ 0, 1, 2,\ . | | ,\ 9, Code\ 11 or Code\ 12) about
the called party's number or the end\(hyof\(hypulsing (ST) signal.
.PP
For each call, a succession of address signals is sent.
.RT
.sp 1P
.LP
3.3.2
\fIEnd\(hyof\(hypulsing (ST) signal\fR
.sp 9p
.RT
.PP
An address signal sent in the forward direction indicating that
there are no more address signals to follow.
.RT
.sp 1P
.LP
3.3.3
\fINature\(hyof\(hyaddress indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating whether the
associated address or line identity is an international, national significant
or subscriber number.
.RT
.sp 1P
.LP
3.3.4
\fINature\(hyof\(hycircuit indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction about the nature of the circuit
or any preceding circuit(s) already engaged in the
connection:
.RT
.LP
\(em
a satellite circuit, or
.LP
\(em
no satellite circuit.
.PP
An international exchange receiving this information will use it (in combination
with the appropriate part of the address information) to
determine the nature of the outgoing circuit to be chosen.
.sp 1P
.LP
3.3.5
\fIOutgoing echo suppressor indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating whether or not an
outgoing half\(hyecho suppressor is included in the connection.
.RT
.sp 1P
.LP
3.3.6
\fIIncoming international call indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating that the call is an
incoming international call.
.RT
.sp 1P
.LP
3.3.7
\fICalling\(hyparty's\(hycategory\fR
.sp 9p
.RT
.PP
Information sent in the forward direction about the category of the calling
party and, in case of semiautomatic calls, about the service language to
be spoken by the incoming, delay and assistance operators.
.PP
The following categories are provided:
.RT
.LP
\(em
operator,
.LP
\(em
ordinary calling subscriber,
.LP
\(em
calling subscriber with priority,
.LP
\(em
data call,
.LP
\(em
test call,
.LP
\(em
payphone.
.sp 1P
.LP
3.3.8
\fIIncomplete calling line identity indicator\fR
.sp 9p
.RT
.PP
An indicator sent in the forward direction indicating that the
calling line identity is incomplete.
.bp
.RT
.sp 1P
.LP
3.3.9
\fIContinuity\(hycheck indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating whether or not a continuity
check will be performed on the circuit concerned or is being (has been)
performed on a previous circuit in the connection.
.RT
.sp 1P
.LP
3.3.10
\fICalling line identity\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating the national significant
number of the calling party.
.RT
.sp 1P
.LP
3.3.11
\fICalling line identity presentation indicator\fR
.sp 9p
.RT
.PP
Information indicating whether or not the calling line identity
presentation is restricted.
.RT
.sp 1P
.LP
3.3.12
\fICalling\(hyline\(hyidentity\(hyunavailable indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating that the
identity of the calling line is not available.
.RT
.sp 1P
.LP
3.3.13
\fICalling party's category unavailable indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction to indicate that the
calling party's category is not available.
.RT
.sp 1P
.LP
3.3.14
\fIOriginal called address not available indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating that the
original called address is not available.
.RT
.sp 1P
.LP
3.3.15
\fIContinuity signal\fR
.sp 9p
.RT
.PP
A signal sent in the forward direction indicating continuity of the preceding
System No.\ 7 speech circuit(s) as well as of the selected speech
circuit to the following international exchange, including verification
of the speech path across the exchange with the specified degree of reliability.
.RT
.sp 1P
.LP
3.3.16
\fIContinuity\(hyfailure signal\fR
.sp 9p
.RT
.PP
A signal sent in the forward direction indicating failure of
continuity of the System No.\ 7 speech circuit.
.RT
.sp 1P
.LP
3.3.17
\fIRedirected call indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating that the call is a
forwarded call.
.RT
.sp 1P
.LP
3.3.18
\fIOriginal called address\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating the address
towards which the call was previously routed (before the redirection
occurred).
.RT
.sp 1P
.LP
3.3.19
\fIAll digital path required indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating the type path required
(64\ kbit/s circuit switched connection\(hytransparent).
.RT
.sp 1P
.LP
3.3.20
\fISignalling path indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating that the
signalling system used since the originating exchange is System No.\ 7.
.RT
.sp 2P
.LP
3.3.21
\fIAdditional signals relating to the closed user group\fR
\fIfacilities\fR
.sp 1P
.RT
.sp 1P
.LP
3.3.21.1
\fIClosed user group call indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating whether or not the
call involves a closed user group and whether or not outgoing access is
allowed for the calling user.
.bp
.RT
.sp 1P
.LP
3.3.21.2
\fIInterlock code\fR
.sp 9p
.RT
.PP
Information sent in the forward direction identifying a closed user group
to which the calling user belongs.
.RT
.sp 1P
.LP
3.3.22
\fIMalicious call identification indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating that the
malicious call identification has been provided or not.
.RT
.sp 1P
.LP
3.3.23
\fIHold indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating whether the
requested holding of the connection is possible or not.
.RT
.sp 1P
.LP
3.3.24
\fITransit exchange identity type indicator\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating the type of
information included as transit exchange identity.
.RT
.sp 1P
.LP
3.3.25
\fITransit exchange identity\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating the identity of the
transit exchange by which the call is established such as signalling
point code or a part of the calling line identity.
.RT
.sp 1P
.LP
3.3.26
\fIIncoming trunk identity\fR
.sp 9p
.RT
.PP
Information sent in the forward direction indicating the identity of the
incoming trunk on which the call is established.
.RT
.sp 1P
.LP
3.3.27
\fISignals related to charging facilities\fR
.sp 9p
.RT
.PP
For further study.
.RT
.sp 1P
.LP
3.3.28
\fICharging information\fR
.sp 9p
.RT
.PP
Information sent in the forward direction for charging and/or
accounting purposes.
.RT
.sp 2P
.LP
3.4
\fIBackward set\(hyup telephone signals\fR
.sp 1P
.RT
.sp 1P
.LP
3.4.1
\fICalling\(hyline\(hyidentity\(hyrequest indicator\fR
.sp 9p
.RT
.PP
Information sent in the backward direction requesting transfer of the calling
line identity from the originating exchange.
.RT
.sp 1P
.LP
3.4.2
\fICalling party's category request indicator\fR
.sp 9p
.RT
.PP
Information sent in the backward direction requesting transfer of the calling
party's category from the originating exchange.
.RT
.sp 1P
.LP
3.4.3
\fIOriginal called address information request indicators\fR
.sp 9p
.RT
.PP
Information sent in the backward direction requesting transfer of the original
called address from the originating exchange.
.RT
.sp 1P
.LP
3.4.4
\fIAddress\(hycomplete signal\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating that all the
address signals required for routing the call to the called party have been
received and that no called\(hyparty's\(hyline\(hycondition signals (electrical)
will
be sent.
.RT
.sp 1P
.LP
3.4.5
\fIAddress\(hycomplete signal, charge\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating that all the
address signals required for routing the call to the called party have been
received, that no called\(hyparty's\(hyline\(hycondition signals (electrical)
will be
sent and that the call should be charged on answer.
.bp
.RT
.sp 1P
.LP
3.4.6
\fIAddress\(hycomplete signal, no\(hycharge\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating that all the
address signals required for routing the call to the called party have been
received, that no called\(hyparty's\(hyline\(hycondition (electrical) will
be sent and that the call should not be charged on answer.
.RT
.sp 1P
.LP
3.4.7
\fIAddress\(hycomplete signal, payphone\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating that all the
address signals required for routing the call to the called party have been
received, that no called\(hyparty's\(hyline\(hycondition (electrical) will
be sent,
that the call should be charged on answer and that the called number is a
payphone station.
.RT
.sp 1P
.LP
3.4.8
\fISubscriber\(hyfree indicator\fR
.sp 9p
.RT
.PP
Information sent in the backward direction indicating that the
called party's line is free.
.RT
.sp 1P
.LP
3.4.9
\fIIncoming echo suppressor indicator\fR
.sp 9p
.RT
.PP
Information sent in the backward direction indicating that an
incoming half\(hyecho suppressor has been inserted or not.
.RT
.sp 1P
.LP
3.4.10
\fICall forwarding indicator\fR
.sp 9p
.RT
.PP
Information sent in the backward direction indicating that the call has
been forwarded to a different address.
.RT
.sp 1P
.LP
3.4.11
\fISignalling path indicator\fR
.sp 9p
.RT
.PP
Information sent in the backward direction indicating that the
signalling system used since the terminating exchange is Signalling System
No.\ 7.
.RT
.sp 1P
.LP
3.4.12
\fICharging information signals\fR
.sp 9p
.RT
.PP
Information sent in the backward direction for charging
and/or accounting purposes.
.RT
.sp 1P
.LP
3.4.13
\fIOutgoing echo suppressor request indicator\fR
.sp 9p
.RT
.PP
Information sent in the backward direction requesting for the
insertion of an outgoing suppressor.
.RT
.sp 1P
.LP
3.4.14
\fIHold request indicator\fR
.sp 9p
.RT
.PP
Information sent in the backward direction indicating that the hold of
the connection is requested. The release of the call will be controlled
by the terminating exchange.
.RT
.sp 1P
.LP
3.4.15
\fIMalicious call identification indicator\fR
.sp 9p
.RT
.PP
Information sent in the backward direction indicating that a
malicious call identification facility has been encountered.
.RT
.sp 1P
.LP
3.4.16
\fISwitching\(hyequipment\(hycongestion signal\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating the failure of the call
set\(hyup attempt due to congestion encountered at international
switching equipment.
.RT
.sp 1P
.LP
3.4.17
\fICircuit\(hygroup\(hycongestion signal\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating the failure of the call
set\(hyup attempt due to congestion encountered on an international
circuit group.
.RT
.sp 1P
.LP
3.4.18
\fINational\(hynetwork\(hycongestion signal\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating the failure of the call
set\(hyup attempt due to congestion encountered in the national
destination network [excluding the busy condition of the called party's
line(s)].
.bp
.RT
.sp 1P
.LP
3.4.19
\fIDigital path not provided signal\fR
.sp 9p
.RT
.PP
Information sent in the backward direction indicating that a
routing which allows the complete digital path requested does not
exist.
.RT
.sp 1P
.LP
3.4.20
\fIAddress\(hyincomplete signal\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating that the number of address
signals received is not sufficient for setting up the call. This
condition may be determined in the incoming international exchange (or
in the national destination network):
.RT
.LP
\(em
immediately after the reception of an ST signal, or
.LP
\(em
on timeout after the latest digit received.
.sp 1P
.LP
3.4.21
\fICall\(hyfailure signal\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating the failure of a call
set\(hyup attempt due to the lapse of a timeout or a fault not covered
by
specific signals.
.RT
.sp 2P
.LP
3.4.22
\fICalled party's line condition signals\fR
.sp 1P
.RT
.sp 1P
.LP
3.4.22.1
\fIUnallocated\(hynumber signal\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating that the
received number is not in use (e.g.,\ spare level, spare code, vacant
subscriber's number).
.RT
.sp 1P
.LP
3.4.22.2
\fISubscriber\(hybusy signal (electrical)\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating that the line(s) connecting
the called party with the exchange is (are) engaged. The
subscriber\(hybusy signal will also be sent in case of complete uncertainty
about the place where the busy or congestions are encountered and in the
case where a discrimination between subscriber\(hybusy and national\(hynetwork
congestion is not possible.
.RT
.sp 1P
.LP
3.4.22.3
\fILine\(hyout\(hyof\(hyservice signal\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating that the called party's
line is out\(hyof\(hyservice or faulty.
.RT
.sp 1P
.LP
3.4.22.4
\fISend\(hyspecial\(hyinformation\(hytone signal\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating that the special information
tone should be returned to the calling party. This tone indicates that
the called number cannot be reached for reasons not covered by other
specific signals and that the unavailability is of a long\(hyterm nature
(see also Recommendation\ Q.35\ [1]).
.RT
.sp 1P
.LP
3.4.23
\fIAccess barred signal\fR
.sp 9p
.RT
.PP
Information sent in the backward direction indicating that the call is
rejected because a compatibility check failed.
.RT
.sp 1P
.LP
3.4.24
\fIMisdialled trunk prefix\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating the erroneous
inclusion of a trunk prefix (for national use).
.RT
.sp 2P
.LP
3.5
\fICall supervision signals\fR
.sp 1P
.RT
.sp 1P
.LP
3.5.1
\fIForward\(hytransfer signal\fR
.sp 9p
.RT
.PP
A signal sent in the forward direction on semiautomatic calls when the
outgoing international exchange operator wants the help of an operator
at the incoming international exchange. The signal will normally serve
to bring an assistance operator (see Recommendation\ Q.101\ [2]) into the
circuit if the call is automatically set up at the exchange. When a call
is completed via an
operator (incoming or delay operator) at the incoming international exchange,
the signal should preferably cause this operator to be recalled.
.bp
.RT
.sp 1P
.LP
3.5.2
\fIAnswer signal, charge\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating that the call is answered
and subject to charge.
.PP
In semiautomatic working, this signal has a supervisory function. In automatic
working, the signal is used:
.RT
.LP
\(em
to start metering the charge to the calling subscriber
(Recommendation\ Q.28\ [3]), and
.LP
\(em
to start the measurement of call duration for international accounting
purposes (Recommendation\ E.260\ [4]).
.sp 1P
.LP
3.5.3
\fIAnswer signal, no charge\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating that the call is answered
but is not subject to charge. It is used for calls to particular
destinations only.
.PP
In semiautomatic working, this signal has a supervisory function. In automatic
working, the reception of this signal shall not start the metering to the
calling subscriber.
.RT
.sp 1P
.LP
3.5.4
\fIAnswer signal, unqualified\fR (basic national use)
.sp 9p
.RT
.PP
A signal sent in the backward direction to indicate that the call is answered.
.RT
.sp 1P
.LP
3.5.5
\fIClear\(hyback signal\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating that the called party
has cleared.
.PP
In semiautomatic working, this signal has a supervisory function. In automatic
working, the arrangements specified in Recommendation\ Q.118\ [5]
apply.
.RT
.sp 1P
.LP
3.5.6
\fIRe\(hyanswer signal\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction indicating that the called party,
after having cleared, again lifts his receiver or in some other way
reproduces the answer condition, e.g.,\ switch\(hyhook flashing.
.RT
.sp 1P
.LP
3.5.7
\fIClear\(hyforward signal\fR
.sp 9p
.RT
.PP
A signal sent in the forward direction to terminate the call or
call attempt and release the circuit concerned. This signal is normally sent
when the calling party clears but also may be a proper response in other
situations as, for example, when reset circuit is received.
.RT
.sp 1P
.LP
3.5.8
\fICalling party clear signal\fR | national option)
.sp 9p
.RT
.PP
A signal sent in the forward direction, when the holding of the
connection is provided, to indicate that the calling party has cleared.
.RT
.sp 2P
.LP
3.6
\fICircuit supervision signals\fR
.sp 1P
.RT
.sp 1P
.LP
3.6.1
\fIRelease\(hyguard signal\fR
.sp 9p
.RT
.PP
A signal sent in the backward direction in response to a
clear\(hyforward signal, or if appropriate to the reset\(hycircuit signal,
when the circuit concerned has been brought into the idle condition.
.RT
.sp 1P
.LP
3.6.2
\fIReset\(hycircuit signal\fR
.sp 9p
.RT
.PP
A signal that is sent to release a circuit when, due to memory
mutilation or other causes, it is unknown whether, for example, a clear\(hyforward
or clear\(hyback signal is appropriate. If at the receiving end the circuit
is
blocked, this signal should remove that condition.
.bp
.RT
.sp 1P
.LP
3.6.3
\fIBlocking signal\fR
.sp 9p
.RT
.PP
A signal sent only for maintenance purposes to the exchange at the other
end of a circuit to cause engaged conditions of that circuit for
subsequent calls outgoing from that exchange. When a circuit is used in the
bothway mode of operation, an exchange receiving the blocking signal must be
capable of accepting incoming calls on that circuit unless it also has
sent a blocking signal. Under conditions covered later, a blocking signal
is also a
proper response to a reset circuit signal.
.RT
.sp 1P
.LP
3.6.4
\fIUnblocking signal\fR
.sp 9p
.RT
.PP
A signal sent to the exchange at the other end of a circuit to
cancel in that exchange the engaged conditions of that circuit caused by an
earlier blocking signal or maintenance\(hyoriented group blocking message.
.RT
.sp 1P
.LP
3.6.5
\fIBlocking\(hyacknowledgement signal\fR
.sp 9p
.RT
.PP
A signal sent in response to a blocking signal indicating that the speech
circuit has been blocked.
.RT
.sp 1P
.LP
3.6.6
\fIUnblocking\(hyacknowledgement signal\fR
.sp 9p
.RT
.PP
A signal sent in response to an unblocking signal indicating that the speech
circuit has been unblocked.
.RT
.sp 1P
.LP
3.6.7
\fIContinuity\(hycheck\(hyrequest signal\fR
.sp 9p
.RT
.PP
A signal sent requesting an independent circuit continuity
test.
.RT
.sp 2P
.LP
3.7
\fICircuit group supervision messages\fR
.sp 1P
.RT
.sp 1P
.LP
3.7.1
\fIMaintenance oriented group blocking message\fR
.sp 9p
.RT
.PP
A message sent for maintenance purposes to the exchange at the
other end of a circuit group to cause an engaged condition on that circuit
group or parts thereof for subsequent calls outgoing from that exchange. An
exchange receiving the maintenance oriented group blocking message must be
capable of accepting incoming calls on the blocked circuits of that circuit
group unless it also has sent a blocking message.
.RT
.sp 1P
.LP
3.7.2
\fIMaintenance oriented group unblocking message\fR
.sp 9p
.RT
.PP
A message sent to the exchange at the other end of a circuit group to cancel
in that exchange the engaged condition on that circuit group or parts thereof
caused by an earlier maintenance\(hyoriented group blocking message or
blocking signal.
.RT
.sp 1P
.LP
3.7.3
\fIHardware failure oriented group blocking message\fR
.sp 9p
.RT
.PP
A message sent for reason of a hardware failure to the exchange at the
other end of a circuit group to cause an engaged condition on that circuit
group or parts thereof. An exchange receiving the hardware failure oriented
group blocking message must be capable of accepting incoming calls on the
blocked circuits of that circuit group unless it also has sent a blocking
message.
.RT
.sp 1P
.LP
3.7.4
\fIHardware failure oriented group unblocking message\fR
.sp 9p
.RT
.PP
A message sent to the exchange at the other end of a circuit group to cancel
in that exchange the engaged condition on that circuit group or parts thereof
caused by an earlier hardware failure oriented group blocking
message.
.RT
.sp 1P
.LP
3.7.5
\fISoftware generated group blocking message (national option)\fR
.sp 9p
.RT
.PP
A message sent for reason of a software generated alarm to the
exchange at the other end of a circuit group to cause an engaged condition
on that circuit group or parts thereof. An exchange receiving the software
generated group blocking message must be capable of accepting incoming calls
on the blocked circuits of that circuit group unless it also has sent a
blocking message.
.bp
.RT
.sp 1P
.LP
3.7.6
\fISoftware generated group unblocking message (national option)\fR
.sp 9p
.RT
.PP
A message sent to the exchange at the other end of a circuit group to cancel
in that exchange the engaged condition on that circuit group or parts thereof
caused by an earlier software generated group blocking message.
.RT
.sp 1P
.LP
3.7.7
\fICircuit group reset message\fR
.sp 9p
.RT
.PP
A message that is sent to release a circuit group or parts thereof when,
due to memory mutilation or other causes, it is unknown which of the
clearing signals is appropriate for the particular circuits within that
circuit group. If at the receiving end circuits are blocked, this message
should remove that condition.
.RT
.sp 1P
.LP
3.7.8
\fIMaintenance oriented group blocking\(hyacknowledgement message\fR
.sp 9p
.RT
.PP
A message sent in response to a maintenance oriented group blocking message
indicating that the circuit group or parts thereof has/have been
blocked.
.RT
.sp 1P
.LP
3.7.9
\fIMaintenance oriented group unblocking\(hyacknowledgement message\fR
.sp 9p
.RT
.PP
A message sent in response to a maintenance oriented group
unblocking message indicating that the circuit group or parts thereof has/have
been unblocked.
.RT
.sp 1P
.LP
3.7.10
\fIHardware failure oriented group blocking\(hyacknowledgement\fR
\fImessage\fR
.sp 9p
.RT
.PP
A message sent in response to a hardware failure oriented group
blocking message indicating that the circuit group or parts thereof has/have
been blocked.
.RT
.sp 1P
.LP
3.7.11
\fIHardware failure oriented group unblocking\(hyacknowledgement\fR
\fImessage\fR
.sp 9p
.RT
.PP
A message sent in response to a hardware failure oriented group
unblocking message indicating that the circuit group or parts thereof has/have
been unblocked.
.RT
.sp 1P
.LP
3.7.12
\fISoftware generated group blocking\(hyacknowledgement message\fR
\fI(national option)\fR
.sp 9p
.RT
.PP
A message sent in response to a software generated group blocking message
indicating that the circuit group or parts thereof has/have been
blocked.
.RT
.sp 1P
.LP
3.7.13
\fISoftware generated group unblocking\(hyacknowledgement message\fR
\fI(national option)\fR
.sp 9p
.RT
.PP
A message sent in response to a software generated group unblocking message
indicating that the circuit group or parts thereof has/have been
unblocked.
.RT
.sp 1P
.LP
3.7.14
\fICircuit group reset\(hyacknowledgement message\fR
.sp 9p
.RT
.PP
A message sent in response to a circuit group reset message
indicating that:
.RT
.LP
i)
if the range field is not coded all zero, the circuits are
reset; or
.LP
ii)
if the range field is coded all zero, the reset of the
circuit group has been started and the reset state of each
circuit concerned will be reported by the appropriate call,
circuit or circuit group supervision
signal/message.
.sp 1P
.LP
3.8
\fIAutomatic congestion control signals\fR
.sp 9p
.RT
.PP
Signals generated by the exchange to indicate that a congestion
threshold has been exceeded (see Recommendation\ Q.542, \(sc\ 5.4.5).
.RT
.sp 1P
.LP
3.8.1
\fICongestion level 1\fR
.sp 9p
.RT
.PP
A signal indicating that the first (less severe) congestion
threshold in an exchange has been exceeded.
.RT
.sp 1P
.LP
3.8.2
\fICongestion level 2\fR
.sp 9p
.RT
.PP
A signal indicating that the second (more severe) congestion
threshold in an exchange has been exceeded.
.bp
.RT
.sp 2P
.LP
\fBReferences\fR
.sp 1P
.RT
.LP
[1]
CCITT Recommendation \fICharacteristics of the dial tone, ringing tone,\fR
\fIbusy tone, congestion tone, special information tone and warning tone,\fR
Rec.\ Q.35.
.LP
[2]
CCITT Recommendation \fIFacilities provided in international\fR
\fIsemiautomatic working\fR , Rec.\ Q.101.
.LP
[3]
CCITT Recommendation \fIDetermination of the moment of the called\fR
\fIsubscriber's answer in the automatic service\fR , Rec.\ Q.28.
.LP
[4]
CCITT Recommendation \fIBasic technical problems concerning the\fR
\fImeasurement and recording of call durations\fR , Rec.\ E.260.
.LP
[5]
CCITT Recommendation \fISpecial release arrangements and indication\fR
\fIof congestion conditions at transit exchanges\fR , Rec.\ Q.118.
\v'1P'
.sp 2P
.LP
\fBRecommendation\ Q.723\fR
.RT
.sp 2P
.sp 1P
.ce 1000
\fBFORMATS\ AND\ CODES\fR
.EF '% Fascicle\ VI.8\ \(em\ Rec.\ Q.723''
.OF '''Fascicle\ VI.8\ \(em\ Rec.\ Q.723 %'
.ce 0
.sp 1P
.LP
\fB1\fR \fBBasic format characteristics\fR
.sp 1P
.RT
.sp 1P
.LP
1.1
\fIGeneral\fR
.sp 9p
.RT
.PP
The telephone user messages are carried on the signalling data link by
means of signal units, the format of which is described in
Recommendation\ Q.703, \(sc\ 2.2.
.PP
The signalling information of each message constitutes the signalling information
field of the corresponding signal unit and consists of an integral number
of octets. It basically contains the \fIlabel\fR , the \fIheading code\fR
and one or more \fIsignals\fR and/or \fIindications\fR . Structure and
function of the label are described in \(sc\ 2; the heading codes and detailed
message formats are
described in \(sc\ 3.
.RT
.sp 1P
.LP
1.2
\fIThe service\fR
\fIinformation octet\fR
.sp 9p
.RT
.PP
The \fIservice information octet\fR | comprises the \fIservice indicator\fR
and the \fIsubservice field\fR .
.PP
The service indicator is used to associate signalling information with
a particular User Part and is only used with message signal units (see
Recommendation\ Q.704, \(sc\ 12.2).
.PP
The information in the subservice field permits a distinction to be
made between national and international signalling messages. In national
applications when this discrimination is not required possibly for certain
national User Parts only, the subservice field can be used independently for
different User Parts.
.PP
The format of the service information octet is shown in
Figure\ 1/Q.723.
.RT
.LP
.rs
.sp 12P
.ad r
\fBFigure\ 1/Q.723, (M), p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
The following codes are used in the fields of the service
information octet:
.LP
a)
The service indicator is coded 0100.
.LP
b)
Subservice field.
.LP
bits
B
A
Spare (see Note)
.LP
bits
D
C
Network indicator
.LP
0
0
International network
.LP
0
1
Spare (for international use only)
.LP
1
0
National network
.LP
1
1
Reserved for national use
.PP
\fINote\fR \ \(em\ The two unused bits in the service information octet
are spare for possible future needs that may require a common solution
for all
international User Parts and Message Transfer Part level\ 3. The bits are
coded\ 00.
.sp 1P
.LP
1.3
\fIFormat principles\fR
.sp 9p
.RT
.PP
The user generated information in the signalling information field is,
in general, divided into a number of subfields which may be either of fixed
or variable length. For a given message type identified by a unique message
heading, the presence of a given subfield may be either mandatory or optional.
The various types of subfields are further defined below.
.RT
.sp 1P
.LP
1.3.1
\fIMandatory subfields\fR
.sp 9p
.RT
.PP
Subfields which have been declared mandatory for a given message
type appear in all messages of that type.
.RT
.sp 1P
.LP
1.3.2
\fIOptional subfields\fR
.sp 9p
.RT
.PP
Subfields which have been declared optional for a given message
type only appear when required in messages of that type. The presence or
absence of each optional field is indicated by the state of a field indicator
located in an indicator field, which in this case is a mandatory
subfield.
.RT
.sp 1P
.LP
1.3.3
\fIFixed length subfields\fR
.sp 9p
.RT
.PP
Subfields which have been declared fixed length for a given message type,
contain the same number of bits in all messages of that type.
.RT
.sp 1P
.LP
1.3.4
\fIVariable length subfields\fR
.sp 9p
.RT
.PP
For subfields which have been declared variable length for a given message
type, the number of bits may vary between messages of that type. The
size of a variable length subfield is indicated in an immediately preceding
fixed length subfield in terms of a predefined unit such as bits, octets or
half\(hyoctets.
.RT
.sp 1P
.LP
1.3.5
\fIOrder of subfield transmission\fR
.sp 9p
.RT
.PP
For a given type of message the various types of subfields are
transmitted in the following order:
.RT
.LP
a)
mandatory subfields,
.LP
b)
optional subfields.
.PP
Within each of these two classes, the order of subfield
transmission is, in general, as follows:
.LP
1)
fixed length subfields (with the exception of the indicator field and
subfields indicating the size of a variable length
subfield),
.LP
2)
variable length subfields.
.sp 1P
.LP
1.3.6
\fIOrder of bit transmission\fR
.sp 9p
.RT
.PP
Within each defined subfield the information is transmitted least significant
bit first.
.RT
.sp 1P
.LP
1.3.7
\fICoding of spare bits\fR
.sp 9p
.RT
.PP
Spare bits are coded 0 unless indicated otherwise.
.bp
.RT
.sp 2P
.LP
\fB2\fR \fBLabel\fR
.sp 1P
.RT
.sp 1P
.LP
2.1
\fIGeneral\fR
.sp 9p
.RT
.PP
The \fIlabel\fR | is an item of information which forms part of every
signalling message and is used by the message routing function at Message
Transfer Part level\ 3 to select the appropriate signalling route and by the
User Part function to identify the particular transaction (e.g.\ the call) to
which the message pertains.
.PP
In general, label information encompasses an explicit or implicit
indication of the message source and destination and, depending on the
application, various forms of transaction identification.
.PP
For messages which are related to circuits or calls, the transaction is
conveniently identified by including the corresponding circuit identity
in the label. This technique applies to messages which pass between adjacent
nodes, and to messages which pass between nodes which are not adjacent;
in this case the technique is known as the pass\(hyalong method. In future,
the
introduction of new subscriber services may require the transfer of call
related messages between exchanges at a time when no circuit is associated
with the call. Such messages could be carried using the services of the
Signalling Connection Control Part SCCP\ [6]. In this case the standard
access to the
Signalling Connection Control Part is used.
.PP
\fINote\fR \ \(em\ The service information octet, the routing label and the
circuit identification code are not included in the information transferred
between the Telephone User Part and the Signalling Connection Control
Part.
.PP
One standard label format is specified (\(sc\ 2.2) for international
use. The same standard label is applicable for national use; admitted
deviations from the format of the standard label are described in
\(sc\ 2.3.
.RT
.sp 2P
.LP
2.2
\fIStandard telephone label\fR
.sp 1P
.RT
.sp 1P
.LP
2.2.1
\fILabel format\fR
.sp 9p
.RT
.PP
The \fIstandard label\fR | has a length of 40 bits and is placed at the
beginning of the signalling information field. The label structure is as
shown in Figure\ 2/Q.723.
.RT
.LP
.rs
.sp 15P
.ad r
\fBFigure\ 2/Q.723, (M), p.
.sp 1P
.RT
.ad b
.RT
.PP
The \fIdestination point code\fR | (DPC) indicates the signalling
point for which the message is intended, while the \fIoriginating point
code\fR
(OPC) indicates the signalling point which is the source of the message. The
\fIcircuit identification code\fR (CIC) indicates one speech circuit among
those
directly interconnecting the destination and the originating points.
.PP
The portion of the label that consists of the destination point code and
originating point code fields and of the four least significant bits of
the circuit identification code field corresponds to the standard routing
label
specified in Recommendation\ Q.704, \(sc\ 13.2.
.bp
.RT
.sp 1P
.LP
2.2.2
\fIDestination and originating point codes\fR
.sp 9p
.RT
.PP
The standard label structure requires that each telephone exchange in its
role as signalling point is allocated a code from code plans established
for the purpose of unambiguous identification of signalling points.
.PP
Separate code plans will be used for the international signalling
network and for different national signalling networks.
.PP
The principles of code allocation which apply to the international
signalling network should be in accordance with Recommendation\ Q.708.
.PP
The destination point code will be the code applicable to the
telephone exchange to which the message is sent. The originating point code
will be the code applicable to the telephone exchange from which the message
is sent.
.RT
.sp 1P
.LP
2.2.3
\fICircuit identification code\fR
.sp 9p
.RT
.PP
The allocation of circuit identification codes to individual
telephone circuits is determined by bilateral agreement and/or in accordance
with applicable predetermined rules.
.PP
Allocation rules for certain applications are defined below:
.RT
.LP
a)
2048\ kbit/s digital path
.LP
For circuits which are derived from a 2048\(hykbit/s digital
path (Recommendations\ G.732\ [1] and G.734\ [2]) the circuit identification
code contains in the 5 least significant bits a binary representation of
the actual number of the time slot which is assigned to the speech circuit.
The remaining bits in the circuit identification code are used where necessary,
to identify one among several systems interconnecting an originating and
destination
point.
.LP
b)
8448\ kbit/s digital path
.LP
For circuits which are derived from a 8448\(hykbit/s digital
path (Recommendation\ G.744\ [3] and G.746\ [4]) the circuit identification
code contains in the 7 least significant bits an identification of the
channel which is assigned to the speech circuit. The codes in Table\ 1/Q.723
are used.
.LP
The remaining bits are used, where necessary, to identify
one among several systems interconnecting an originating and destination
point.
.LP
c)
Frequency division multiplex (FDM) systems in networks
using the 2048\(hykbit/s pulse code modulation standard
.LP
For FDM systems existing in
networks that also use the 2048\(hykbit/s pulse code modulation standard, the
circuit identification code contains in the 6 least significant bits the
identification of a channel within a group of 60\ channels carried by 5 basic
FDM groups which may or may not be part of the same
supergroup.
.LP
The codes in Table 2/Q.723 are used.
.LP
.sp 4
.ce
\fBH.T. [T1.723]\fR
.ce
TABLE\ 1/Q.723
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(30p) | lw(18p) | lw(24p) .
0000000 channel 1
.T&
cw(30p) | lw(18p) | lw(24p) .
0000001 | 0011111 channel 2 \ | channel 32
.T&
cw(30p) | lw(18p) | lw(24p) .
0100000 | 1111110 channel 33 \ | channel 127
.T&
cw(30p) | lw(18p) | lw(24p) .
1111111 channel 128
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau\ 1/Q.723, [T1.723], p.
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [T2.723]\fR
.ce
TABLE\ 2/Q.723
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(24p) | lw(18p) | lw(24p) | lw(6p) | lw(48p) .
000000 unallocated
_
.T&
cw(24p) | lw(18p) | lw(24p) | lw(6p) | cw(48p) .
000001 | 001100 channel 1 \ | channel 12 1st basic (FDM) group
_
.T&
cw(24p) | lw(18p) | lw(24p) | lw(6p) | cw(48p) .
{
001101
001110
001111
010000
010001
|
011001
} {
channel 1
channel 2
channel 3
unallocated
channel 4
\ |
channel 12
} 2nd basic (FDM) group
_
.T&
cw(24p) | lw(18p) | lw(24p) | lw(6p) | cw(48p) .
{
011010
|
011111
100000
100001
|
100110
} {
channel 1
\ |
channel 6
unallocated
channel 7
\ |
channel 12
} 3rd basic (FDM) group
_
.T&
cw(24p) | lw(18p) | lw(24p) | lw(6p) | cw(48p) .
{
100111
|
101111
110000
110001
110010
110011
} {
channel 1
\ |
channel 9
unallocated
channel 10
channel 11
channel 12
} 4th basic (FDM) group
_
.T&
cw(24p) | lw(18p) | lw(24p) | lw(6p) | cw(48p) .
110100 | 111111 channel 1 \ | channel 12 5th basic (FDM) group
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau\ 2/Q.723, [T2.723], p.
.sp 1P
.RT
.ad b
.RT
.LP
.sp 1
.sp 1P
.LP
2.3
\fIOptional national labels\fR
.sp 9p
.RT
.PP
For the purpose of satisfying the requirements imposed by specific characteristics
of some national signalling networks, field sizes different
from those specified for the standard label are admitted for the destination
point code, originating point code and circuit identification code fields in
national labels.
.RT
.sp 2P
.LP
\fB3\fR \fBTelephone signal message formats and codes\fR
.sp 1P
.RT
.sp 1P
.LP
3.1
\fIGeneral\fR
.sp 9p
.RT
.PP
All telephone signal messages contain a \fIheading\fR | consisting of
two parts, heading code\ H0 and heading code\ H1. Code\ H0 identifies a
specific message group (see Recommendation\ Q.722, \(sc\ 3.2.1) while\
H1 either
contains a signal code or in case of more complex messages, identifies the
format of these messages. The allocation of the H0 and H1\ code is summarized
in Table\ 3/Q.723.
.bp
.RT
.ce
\fBH.T. [1T7.723]\fR
.ce
TABLE\ 3/Q.723
.ce
\fBHeading code allocation\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(24p) | lw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) .
Message group \ \ H1 | 0 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111
_
.T&
cw(24p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) sw(12p) sw(12p) sw(12p) sw(12p) sw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) , ^ | ^ | l | l | l | l | l | l | l | l | l | l | l | l | l | l | l | l.
{
0000
.
.
.
.
.
Spare, reserved for national use
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
}
_
.T&
cw(24p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) .
FAM 0001 IAM IAI SAM SAO
_
.T&
cw(24p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) .
FSM 0010 GSM COT CCF
_
.T&
cw(24p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) .
BSM 0011 GRQ
_
.T&
cw(24p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) .
SBM 0100 ACM CHG
_
.T&
cw(24p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | lw(12p) | lw(12p) | lw(12p) .
UBM 0101 SEC CGC NNC ADI CFL SSB UNN LOS SST ACB DPN MPR EUM
_
.T&
cw(24p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | lw(12p) | lw(12p) | lw(12p) .
CSM 0110 ANU ANC ANN CBK CLF RAN FOT CCL
_
.T&
cw(24p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | lw(12p) | lw(12p) | lw(12p) .
CCM 0111 RLG BLO BLA UBL UBA CCR RSC
_
.T&
cw(24p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | cw(12p) | lw(12p) | lw(12p) .
GRM 1000 MGB MBA MGU MUA HGB HBA HGU HUA GRS GRA SGB\ua\d\u)\d SBA\ua\d\u)\d SGU\ua\d\u)\d SUA\ua\d\u)\d
_
.T&
cw(24p) | cw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(96p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) .
1001 RESERVED
_
.T&
cw(24p) | cw(12p) | cw(12p) | cw(12p) | lw(12p) | lw(12p) | lw(96p) | lw(48p) , l | l | l | l | l | l ^ | | l.
CNM 1010 ACC {
1011
Spare reserved for international
and basic national use
}
_
.T&
cw(24p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(96p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) .
1100
_
.T&
cw(24p) | cw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(96p) | lw(48p) , l | l | l | l | l | l ^ | | l.
1101 {
1110
Spare, reserved for national use
}
_
.T&
cw(24p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) | lw(96p) | lw(12p) | lw(12p) | lw(12p) | lw(12p) .
{
1111
\ua\d\u)\d
National option.
}
.TE
.nr PS 9
.RT
.ad r
\fBTableau 3/Q.723, [1T7.723], p.5\fR
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 10P
.ad r
Blanc
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [2T7.723] \ \ \
.ce
TABLEAU AVEC (AR)\fR
.ce
\fBAbbreviations used in Table 3/Q.723\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
lw(120p) .
ACB Access barred signal
.T&
lw(120p) .
{
ACC
Automatic congestion control information message
}
.T&
lw(120p) .
{
ACM
Address complete message (note)
}
.T&
lw(120p) .
ADI Address incomplete signal
.T&
lw(120p) .
ANC Answer signal, charge
.T&
lw(120p) .
ANN Answer signal, no charge
.T&
lw(120p) .
{
ANU
Answer signal, unqualified
}
.T&
lw(120p) .
{
BLA
Blocking\(hyacknowledgement signal
}
.T&
lw(120p) .
BLO Blocking signal
.T&
lw(120p) .
{
BSM
Backward set\(hyup message
}
.T&
lw(120p) .
CBK Clear\(hyback signal
.T&
lw(120p) .
{
CCF
Continuity\(hyfailure signal
}
.T&
lw(120p) .
{
CCL
Calling party clear signal
}
.T&
lw(120p) .
{
CCM
Circuit supervision message
}
.T&
lw(120p) .
{
CCR
Continuity\(hycheck\(hyrequest signal
}
.T&
lw(120p) .
CFL Call\(hyfailure signal
.T&
lw(120p) .
{
CGC
Circuit\(hygroup\(hycongestion signal
}
.T&
lw(120p) .
CHG Charging message
.T&
lw(120p) .
CLF Clear\(hyforward signal
.T&
lw(120p) .
{
CNM
Circuit network management message group
}
.T&
lw(120p) .
COT Continuity signal
.T&
lw(120p) .
CSM Call supervision message
.T&
lw(120p) .
{
DPN
Digital path not provided signal
}
.T&
lw(120p) .
{
EUM
Extended unsuccessful backward set\(hyup information
message
}
.T&
lw(120p) .
FAM Forward address message
.T&
lw(120p) .
{
FOT
Forward\(hytransfer signal
}
.T&
lw(120p) .
FSM Forward set\(hyup message
.T&
lw(120p) .
{
GRA
Circuit group reset\(hyacknowledgement message
}
.T&
lw(120p) .
{
GRM
Circuit group supervision messages
}
.T&
lw(120p) .
GRQ General request message
.T&
lw(120p) .
{
GRS
Circuit group reset message
}
.T&
lw(120p) .
{
GSM
General forward set\(hyup information message
}
.T&
lw(120p) .
{
HBA
Hardware failure oriented group blocking\(hyacknowledgement
message
}
.TE
.nr PS 9
.RT
.ad r
\fBTableau 3/Q.723, [2T7.723], p.6\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
3.2
\fIHeading code\fR \fIH0\fR
.sp 9p
.RT
.PP
The \fIheading code\fR | H0 occupies the 4\(hybit field following the
label and is coded as follows:
.RT
.LP
0000
spare, reserved for national use
.LP
0001
forward address messages
.LP
0010
forward set\(hyup messages
.LP
0011
backward set\(hyup request messages
.LP
0100
successful backward set\(hyup information messages
.LP
0101
unsuccessful backward set\(hyup information messages
.LP
0110
call supervision messages
.LP
0111
circuit supervision messages
.LP
1000
circuit group supervision messages
.LP
1001
reserved
.LP
1010
circuit network management messages
.LP
1011
reserved for international and basic national use
.LP
1100
.LP
\ to\
reserved for national use
.LP
1111
.sp 1P
.LP
3.3
\fIForward address messages\fR
.sp 9p
.RT
.PP
The following types of \fIforward address messages\fR | are specified
and are each identified by a different heading code\ H1:
.RT
.LP
\(em
Initial address message.
.LP
\(em
Initial address message with additional information.
.LP
\(em
Subsequent address message (with one or more address
signals).
.LP
\(em
Subsequent address message with one (address)
signal.
.sp 1P
.LP
3.3.1
\fIInitial address message\fR
.sp 9p
.RT
.PP
The basic format of the \fIinitial address message\fR | is shown on
Figure\ 3/Q.723.
.RT
.LP
.rs
.sp 19P
.ad r
\fBFigure\ 3/Q.723, (M), p.\fR
.sp 1P
.RT
.ad b
.RT
.PP
The following codes are used in the fields of the initial address message.
.LP
a)
Label: see \(sc 2
.LP
b)
Heading code H0 is coded 0001
.LP
c)
Heading code H1 is coded 0001
.LP
d)
Calling party category
.bp
.LP
bits
F
E
D
C
B
A
.LP
0
0
0
0
0
0
unknown source (Note\ 1)
.LP
0
0
0
0
0
1
operator, language French
.LP
0
0
0
0
1
0
operator, language English
.LP
0
0
0
0
1
1
operator, language German
.LP
0
0
0
1
0
0
operator, language Russian
.LP
0
0
0
1
0
1
operator, language Spanish
.LP
0
0
0
1
1
0
.LP
0
0
0
1
1
1
.LP
0
0
1
0
0
0
.LP
\-v'2P'
\-v'1p'
available to Administrations for selecting
a particular language provided by mutual agreement
\v'5p'
.LP
0
0
1
0
0
1
reserved (see
Recommendation\ Q.104\ [5])
(Note\ 2)
.LP
0
0
1
0
1
0
ordinary calling subscriber
.LP
0
0
1
0
1
1
calling subscriber with priority
.LP
0
0
1
1
0
0
data call
.LP
0
0
1
1
0
1
test call
.LP
0
0
1
1
1
0
spare
.LP
0
0
1
1
1
1
payphone
.LP
0
1
0
0
0
0
.LP
\
\
\ to
spare
.LP
1
1
1
1
1
1
.PP
\fINote\ 1\fR \ \(em\ The calling party category \*Qunknown source\*U is
classified, for the time being, for basic national use. The use of this
category in the international network is for further study.
.PP
\fINote\ 2\fR \ \(em\ In national networks, code 001001 may be used to
indicate that the calling party is a national operator.
.RT
.LP
e)
Spare
.LP
The bits in this field are spare for international
allocation.
.LP
f
)
Message indicators
.LP
bits
B
A:
nature of address indicator
.LP
0
0
subscriber number
.LP
0
1
spare, reserved for national use
.LP
1
0
national (significant) number
.LP
1
1
international number
.LP
bits
D
C:
nature\(hyof\(hycircuit indicator
.LP
0
0
no satellite circuit in the
connection
.LP
0
1
one satellite circuit in the
connection
.LP
1
0
spare
.LP
1
1
spare
.LP
bits
F
E:
continuity\(hycheck indicator
.LP
0
0
continuity\(hycheck not required
.LP
0
1
continuity\(hycheck required on this
circuit
.LP
1
0
continuity\(hycheck performed on a previous
circuit
.LP
1
1
spare
.LP
bit
G:
echo\(hysuppressor indicator
.LP
0
outgoing half echo suppressor not included
.LP
1
outgoing half echo suppressor included
.LP
bit
H:
incoming international call indicator
.LP
0
call other than international incoming
.LP
1
incoming international call
.LP
bit
I:
redirected call indicator
.LP
0
not a redirected call
.LP
1
redirected call
.LP
bit
J:
all\(hydigital\(hypath\(hyrequired indicator
.LP
0
ordinary call
.LP
1
digital path required
.LP
bit
K:
signalling path indicator
.LP
0
any path
.LP
1
all signalling system No. 7 path
.LP
bit
L:
spare
.PP
\fINote\fR \ \(em\ The spare indicator may be used, e.g.,\ to provide the
\(*m/A law conversion control, pending further study.
.bp
.LP
g)
Number of address signals
.LP
A code expressing in pure binary representation the number of address
signals contained in the initial address message,
except for the code\ 0000 to which the meaning 16\ digits
including ST signal is assigned.
.LP
h)
Address signals
.LP
0000\ digit 0
.LP
0001\ digit 1
.LP
0010\ digit 2
.LP
0011\ digit 3
.LP
0100\ digit 4
.LP
0101\ digit 5
.LP
0110\ digit 6
.LP
0111\ digit 7
.LP
1000\ digit 8
.LP
1001\ digit 9
.LP
1010\ spare
.LP
1011\ code 11
.LP
1100\ code 12
.LP
1101\ spare
.LP
1110\ spare
.LP
1111\ ST
.LP
The most significant address signal is sent first.
Subsequent address signals are sent in successive 4\(hybit fields.
.LP
i)
Filler
.LP
In case of an odd number of address signals, the filler code 0000 is
inserted after the last address signal. This ensures that the variable
length field which contains the address signals consists of an integral
number of octets.
.sp 1P
.LP
3.3.2
\fIInitial address message with additional information\fR
.sp 9p
.RT
.PP
The basic format of the \fIinitial address message with additional\fR \fIinformation\fR
| is shown in Figure\ 4/Q.723.
.RT
.LP
.rs
.sp 26P
.ad r
\fBFigure\ 4/Q.723, (MC), p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
The following codes are used in the initial address message with additional
information:
.LP
a)
Label: see \(sc 2
.LP
b)
Heading code H0 is coded 0001
.LP
c)
Heading code H1 is coded 0010
.LP
d)
Calling party category: [see \(sc\ 3.3.1 | )]
.LP
e)
Message indicators: [see \(sc\ 3.3.1 | )]
.LP
f
)
Number of address signals: \fR [see \(sc\ 3.3.1 | )]
.LP
g)
Address signals: [see \(sc\ 3.3.1 | )]
.LP
h)
First indicator octet
.LP
bit
A:
network capability or user facility information
indicator
.LP
0
network capability or user facility information
not included
.LP
1
network capability or user facility
information included
.LP
bit
B:
closed user group information indicator
.LP
0
closed user group information not
included
.LP
1
closed user group information included
.LP
bit
C:
additional calling party information
indicator
.LP
0
additional calling party information not
included
.LP
1
additional calling party information
included
.LP
bit
D:
additional routing information indicator
.LP
0
additional routing information not
included
.LP
1
additional routing information included
.LP
bit
E:
calling line identity indicator
.LP
0
calling line identity not included
.LP
1
calling line identity included
.LP
bit
F:
original called address indicator
.LP
0
original called address not included
.LP
1
original called address included
.LP
bit
G:
charging information indicator
.LP
0
charging information not included
.LP
1
charging information included
.LP
bit
H:
spare, reserved for indicating the presence or absence of a second indicator
octet
.LP
i)
Network capability or user facility information: spare,
reserved for national use. (This optional field may be used
in national applications to indicate specific network
capabilities and/or user facility information.)
.LP
j
)
Closed user group (CUG) information
.LP
The basic format of the closed user group information field is shown
in Figure\ 4a/Q.723.
.ce
\fBH.T. [T3.723]\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(36p) | lw(36p) | lw(36p) .
DCBA
_
.T&
cw(36p) | cw(36p) | cw(36p) .
Interlock code Spare CUG indicator
_
.T&
cw(36p) | cw(36p) | cw(36p) .
32 4 {
4
FIGURE\ 4a/Q.723
\fBClosed user group information field\fR
}
.TE
.nr PS 9
.RT
.ad r
\fBFigure 4a/Q.723 (comme tableau) [T3.723], p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.LP
The following codes are used in the subfields of the closed user group
information field.
.LP
\(em
bits
B
A:
CUG call indicator
.LP
0
0
ordinary call
.LP
0
1
successful check
.LP
1
0
outgoing access allowed
.LP
1
1
outgoing access not allowed
.LP
\(em
bits
C
D:
spare
.LP
\(em
Interlock code
.LP
A code identifying the closed user group involved in
the call. The nature of this code is for further study.
.LP
k)
Additional calling party information: for further study.
(This optional field is of fixed length and will indicate
additional information concerning the calling party, which is
not carried by the calling party's category
indicator.)
.LP
l)
Additional routing information: for further study.
(This optional field is of fixed length and will indicate that
the call has to be routed in some particular way, due for
example to additional customer services.)
.LP
m)
Calling line identity
.LP
The basic format of the calling line identity field is shown
in Figure\ 4b/Q.723.
.ce
\fBH.T. [T4.723]\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(36p) | cw(36p) | lw(36p) .
DCBA DCBA
_
.T&
cw(36p) | cw(36p) | cw(36p) .
Calling line identity Number of address signals Address indicator
_
.T&
cw(36p) | cw(36p) | cw(36p) .
n | (mu | 4 {
4
FIGURE\ 4b/Q.723
\fBCalling line identity field\fR
}
.TE
.nr PS 9
.RT
.ad r
\fBFigure 4b/Q.723 (comme tableau) [T4.723], p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
The following codes are used in the subfields of the
calling line identity field.
.LP
\(em
Address indicators:
.LP
bits
B
A:
nature of address indicator
.LP
0
0
subscriber number
.LP
0
1
spare, reserved for national use
.LP
1
0
national significant number
.LP
1
1
international number
.LP
bit
C:
calling line identity presentation
indicator
.LP
0
calling line identity presentation not
restricted
.LP
1
calling line identity presentation
restricted
.LP
bit
D:
incomplete calling line identity
indicator
.LP
0
no indication
.LP
1
incomplete calling line identity
.LP
\(em
Number of address signals
.LP
bits
D
C
B
A
.LP
0
0
0
0
calling line identity
not available indicator
.LP
0
0
0
1
.LP
\ \ to
.LP
1
1
1
1
.LP
\-v'2P'
\-v'1p'
a code expressing in pure binary representation the
number of address signals.
\v'5p'
.LP
\(em
Calling line address signals
.LP
Each signal is coded as indicated in \(sc\ 3.3.1\ h) as
applicable.
.bp
.LP
n)
Original called address
.LP
The basic format of the original called address field is
shown in Figure\ 4c/Q.723.
.ce
\fBH.T. [T5.723]\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(36p) | cw(36p) | lw(36p) .
DCBA DCBA
_
.T&
cw(36p) | cw(36p) | cw(36p) .
Original called address Number of address signals Address indicators
_
.T&
cw(36p) | cw(36p) | cw(36p) .
n | (mu | 4 {
4
FIGURE\ 4c/Q.723
\fBOriginal called address field\fR
}
.TE
.nr PS 9
.RT
.ad r
\fBFigure 4c/Q.723 (comme tableau) [T5.723], p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
The following codes are used in the subfields of the
original address field:
.LP
\(em
Address indicator
.LP
bits
B
A:
nature of address indicator
.LP
0
0
subscriber number
.LP
0
1
spare, reserved for national use
.LP
1
0
national (significant) number
.LP
1
1
international number
.LP
bits
D
C:
spare
.LP
\(em
Number of address signals
.LP
bits
D
C
B
A
.LP
0
0
0
0
original called address
not available
.LP
0
0
0
1
.LP
\ \ to
.LP
1
1
1
1
.LP
\-v'2P'
\-v'1p'
a code expressing in pure binary representation the
number of address signals.
\v'5p'
.LP
\(em
Original called address signals
.LP
Each signal is coded as indicated in \(sc\ 3.3.1\ h) as
applicable.
.LP
o)
Charging information: for further study. (This optional
field will contain information to be sent to a successive exchange for
charging and/or accounting purposes.)
.sp 1P
.LP
3.3.3
\fISubsequent address message\fR
.sp 9p
.RT
.PP
The basic format of the \fIsubsequent address\fR | message (SAM) is
shown in Figure\ 5/Q.723.
.RT
.LP
.rs
.sp 10P
.ad r
\fBFigure 5/Q.723, (M), p.
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
The following codes are used in the fields of the subsequent
address message:
.LP
a)
Label: see \(sc\ 2
.LP
b)
Heading code H0 is coded 0001
.LP
c)
Heading code H1 is coded 0011
.LP
d)
Address signal is coded as indicated in \(sc\ 3.3.1 | )
as applicable
.LP
e)
Number of address signals: a code expressing in pure
binary representation the number of address signals
contained in the subsequent address message.
.sp 1P
.LP
3.3.4
\fISubsequent address message with one signal\fR
.sp 9p
.RT
.PP
The basic format of the \fIsubsequent address message with one\fR
\fIsignal\fR | is shown in Figure\ 6/Q.723.
.RT
.LP
.rs
.sp 10P
.ad r
\fBFigure 6/Q.723, (M), p.
.sp 1P
.RT
.ad b
.RT
.PP
The following codes are used in the fields of the subsequent
address message with one signal:
.LP
a)
Label: see \(sc\ 2
.LP
b)
Heading code H0 is coded 0001
.LP
c)
Heading code H1 is coded 0100
.LP
d)
Address signal is coded as indicated in \(sc\ 3.3.1 | )
as applicable.
.sp 1P
.LP
3.4
\fIForward set\(hyup messages\fR
.sp 9p
.RT
.PP
The following types of forward set\(hyup messages are specified and
are each identified by a different heading code\ H1:
.RT
.LP
\(em
general forward set\(hyup information message,
.LP
\(em
continuity\(hycheck message.
.PP
Unallocated H1 codes in this message group are spare.
.sp 1P
.LP
3.4.1
\fIGeneral forward set\(hyup information message\fR
.sp 9p
.RT
.PP
The basic format of the general forward set\(hyup information message is
shown in Figure\ 7/Q.723.
.RT
.LP
.rs
.sp 11P
.ad r
\fBFigure\ 7/Q.723, (M), p.
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
The following codes are used in the fields of the general forward set\(hyup
information message:
.LP
a)
Label: see \(sc\ 2
.LP
b)
Heading code H0 is coded 0010
.LP
c)
Heading code H1 is coded 0001
.LP
d)
Response type indicator
.LP
bit
A:
calling party category indicator
.LP
0
calling party category not included
.LP
1
calling party category included
.LP
bit
B:
calling line identity indicator
.LP
0
calling line identity not included
.LP
1
calling line identity included
.LP
bit
C:
incoming trunk and transit exchange: identity indicator
.LP
0
incoming trunk and transit exchange identity
not included
.LP
1
incoming trunk and transit exchange identity
included
.LP
bit
D:
original called address indicator
.LP
0
original called address not included
.LP
1
original called address included
.LP
bit
E:
outgoing echo suppressor indicator
.LP
0:
outgoing half echo suppressor not included
.LP
1:
outgoing half echo suppressor included
.LP
bit
F:
malicious call identification indicator
.LP
0
malicious call identification not provided
.LP
1
malicious call identification provided
.LP
bit
G:
hold indicator
.LP
0
hold not provided
.LP
1
hold provided
.LP
bit
H:
spare
.LP
e)
Calling party category:
.LP
bits
F
E
D
C
B
A
.LP
0
0
0
0
0
0
unknown
source/calling party category unavailable indicator
.LP
0
0
0
0
0
1
.LP
\
\
\ to
(see \(sc\ 3.3.1\ d))
.LP
1
1
1
1
1
1
.LP
f
)
Calling line identity:
.LP
Format and codes are the same as used in the calling line
identity contained in the initial address message with
additional information (see \(sc\ 3.3.2).
.LP
g)
Incoming trunk and transit exchange identity:
.LP
The basic format of the incoming trunk and transit exchange
identity field is shown in
Figure\ 8/Q.723.
.ce
\fBH.T. [T6.723]\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(36p) | cw(36p) | cw(36p) | lw(36p) | lw(36p) | lw(36p) .
DCBA DCBA DCBA
_
.T&
cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) .
Incoming trunk identity Field length indicator Spare Transit exchange identity {
Exchange
identity
length
indicator
} Identity type indicator
_
.T&
cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) .
n | (mu | 4 4 n | (mu | 4 {
4
FIGURE\ 8/Q.723
\fBIncoming trunk and transit exchange identity field\fR
}
.TE
.nr PS 9
.RT
.ad r
\fBFigure 8/Q.723 (comme tableau) [T6.723], p.\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
The following codes are used in the subfields of the
incoming trunk and transit exchange identity field:
.LP
\(em
Identity type indicator
.LP
bits
B
A:
.LP
0
0
spare
.LP
0
1
signalling point code
.LP
1
0
available part of calling line identity
.LP
1
1
spare
.LP
bits
D
C:
spare
.LP
\(em
Exchange identity length indicator
.LP
A code expressing in pure binary representation the number of address
signals included in the transit exchange identity subfield for the case
when part of the calling line identity is used for this purpose.
.LP
When the transit exchange is identified by the signalling
point code, this subfield is coded 0000.
.LP
\(em
Transit exchange identity
.LP
A code consisting of either:
.LP
i)
the signalling point code of the exchange, or
.LP
ii)
a part of the calling line identity, in which case
each address digit contained in this identity is coded as
indicated in \(sc\ 3.3.1\ h) where applicable.
.LP
\(em
Field length indicator
.LP
A code indicating in pure binary representation the number
of octets in the incoming trunk identity field.
.LP
Code 0000 indicates that the incoming trunk identity is not
provided.
.LP
\(em
Incoming trunk identity
.LP
A code contained in a maximum of 15 octets, identifying the
incoming trunk. The encoding of the incoming trunk identity is
for further study.
.LP
h)
Original called address
.LP
See \(sc\ 3.3.2\ n).
.sp 1P
.LP
3.4.2
\fIContinuity\(hycheck message\fR
.sp 9p
.RT
.PP
The basic format of the \fIcontinuity\(hycheck\fR | message is shown in
Figure\ 9/Q.723.
.RT
.LP
.rs
.sp 11P
.ad r
\fBFigure\ 9/Q.723, (M), p.
.sp 1P
.RT
.ad b
.RT
.PP
The following codes are used in the fields of the continuity\(hycheck message:
.LP
a)
Label: see \(sc\ 2
.LP
b)
Heading code H0 is coded 0010
.LP
c)
Heading code H1 contains signal codes as follows:
.LP
0011\ continuity signal
.LP
0100\ continuity\(hyfailure signal
.bp
.sp 1P
.LP
3.5
\fIBackward set\(hyup request message\fR
.sp 9p
.RT
.PP
The following type of backward set\(hyup request message is specified and
is identified by one of the heading codes H1. The other H1 codes in this
message group are spare.
.RT
.sp 1P
.LP
3.5.1
General request message\fR
.sp 9p
.RT
.PP
The basic format of the general \fIrequest\fR | message is shown
in Figure 10/Q.723.
.RT
.LP
.rs
.sp 13P
.ad r
\fBFigure\ 10/Q.723, (M), p.
.sp 1P
.RT
.ad b
.RT
.PP
The following codes are used in the fields of the general request message:
.LP
a)
Label: see \(sc 2
.LP
b)
Heading code H0 is coded 0011
.LP
c)
Heading code H1 is coded 0001
.LP
d)
Request type indicators
.LP
bit
A:
calling party category request indicator
.LP
0
no calling party category request
.LP
1
calling party category request
.LP
bit
B:
calling line identity request indicator
.LP
0
no calling line identity request
.LP
1
calling line identity request
.LP
bit
C:
original called address request
.LP
0
no original called address request
.LP
1
original called address request
.LP
bit
D:
malicious call identification indicator
(national option)
.LP
0
no malicious call identification encountered
.LP
1
malicious call identification encountered
.LP
bit
E:
hold request indicator
.LP
0
hold not requested
.LP
1
hold requested
.LP
bit
F:
echo suppressor request indicator
.LP
0
no outgoing half echo suppressor requested
.LP
1
outgoing half echo suppressor requested
.LP
bit
GH:
spare
.sp 1P
.LP
3.6
\fISuccessful backward set\(hyup information messages\fR
.sp 9p
.RT
.PP
The following types of successful backward set\(hyup information
messages are specified and are each identified by a different heading
code\ H1:
.RT
.LP
\(em
address\(hycomplete message
.LP
\(em
charging message.
.bp
.sp 1P
.LP
3.6.1
\fIAddress\(hycomplete message\fR
.sp 9p
.RT
.PP
The basic format of the \fIaddress\(hycomplete\fR | message is shown in
Figure\ 11/Q.723.
.RT
.LP
.rs
.sp 15P
.ad r
\fBFigure\ 11/Q.723, (M), p.
.sp 1P
.RT
.ad b
.RT
.PP
The following codes are used in the fields of the address\(hycomplete message:
.LP
a)
Label: see \(sc\ 2
.LP
b)
Heading code H0 is coded 0100
.LP
c)
Heading code H1 is coded 0001
.LP
d)
Message indicators
.LP
bits
B
A:
type of address\(hycomplete signal
indicators
.LP
0
0
address\(hycomplete signal
.LP
0
1
address\(hycomplete signal, charge
.LP
1
0
address\(hycomplete signal, no charge
.LP
1
1
address\(hycomplete signal, payphone
.LP
bit
C:
subscriber\(hyfree indicator
.LP
0
no indication
.LP
1
subscriber\(hyfree
.LP
bit
D:
incoming echo suppressor indicator
.LP
0
no incoming half echo suppressor included
.LP
1
incoming half echo suppressor included
.LP
bit
E:
call forwarding indicator
.LP
0
call not forwarded
.LP
1
call forwarded
.LP
bit
F:
signalling path indicator
.LP
0
any path
.LP
1
all signalling system No. 7 path
.LP
bits
G
H:
spare, for national use (may be used to
indicate call redirection, holding of the connection
or the end\(hyto\(hyend signalling method to be used).
.PP
\fINote\fR \ \(em\ The address\(hycomplete signal without qualification is
classified for the time being in the basic national category of signals. The
use of this signal in the international network is for further study.
.bp
.sp 1P
.LP
3.6.2
\fICharging message\fR | (see Note)
.sp 9p
.RT
.PP
The basic format of the \fIcharging\fR | message is shown in
Figure\ 12/Q.723.
.RT
.LP
.rs
.sp 13P
.ad r
\fBFigure\ 12/Q.723, (M), p.
.sp 1P
.RT
.ad b
.RT
.PP
The following codes are used in the fields of the charging
message:
.LP
a)
Label: see \(sc\ 2
.LP
b)
Heading code H0 is coded 0100
.LP
c)
Heading code H1 is coded 0010
.LP
d)
Charging information
.PP
(Possible formats and codes of the charging information field are shown
in Annex A.)
.PP
\fINote\fR \ \(em\ The charging message is classified, for the time being, in
the basic national category of messages. The use of this message in the
international network is for further study.
.RT
.sp 2P
.LP
3.7
\fIUnsuccessful backward set\(hyup information messages\fR
.sp 1P
.RT
.sp 1P
.LP
3.7.1
\fISimple unsuccessful backward set\(hyup information message\fR
.sp 9p
.RT
.PP
The basic format of the simple unsuccessful backward set\(hyup
information message is shown in
Figure\ 13/Q.723.
.RT
.LP
.rs
.sp 13P
.ad r
\fBFigure\ 13/Q.723, (M), p.
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
The following codes are used in the fields of the simple
unsuccessful backward set\(hyup information message.
.LP
a)
Label: see \(sc\ 2
.LP
b)
Heading code H0 is coded 0101
.LP
c)
Heading code H1 contains signal codes as follows:
.LP
0000
spare
.LP
0001
switching\(hyequipment\(hycongestion signal
.LP
0010
circuit\(hygroup\(hycongestion signal
.LP
0011
national\(hynetwork\(hycongestion signal
.LP
0100
address\(hyincomplete signal
.LP
0101
call\(hyfailure signal
.LP
0110
subscriber\(hybusy signal (electrical)
.LP
0111
unallocated\(hynumber signal
.LP
1000
line\(hyout\(hyof\(hyservice signal
.LP
1001
send\(hyspecial\(hyinformation\(hytone signal
.LP
1010
access barred signal
.LP
1011
digital path not provided signal
.LP
1100
misdialled trunk prefix signal (for national use)
.LP
1101
.LP
\ to
spare
.LP
1110
.sp 1P
.LP
3.7.2
\fIExtended unsuccessful backward set\(hyup information message\fR
.sp 9p
.RT
.PP
The basic format of the extended unsuccessful backward set\(hyup
information message is shown in
Figure\ 13a/Q.723.
.RT
.LP
.rs
.sp 12P
.ad r
\fBFigure\ 13a/Q.723, (M), p.
.sp 1P
.RT
.ad b
.RT
.PP
The following codes are used in the fields of the extended
unsuccessful backward set\(hyup information message:
.LP
a)
Label: see \(sc\ 2
.LP
b)
Heading code H0 is coded 0101
.LP
c)
Heading code H1 contains signal code 1111
.LP
d)
Octet indicator
.LP
bits
D
C
B
A:
unsuccessful indicator
.LP
0
0
0
0
spare
.LP
0
0
0
1
subscriber busy
.LP
0
0
1
0
.LP
\ \ to
spare
.LP
1
1
1
1
.LP
bits
H
G
F
E:
spare.
.LP
e)
Signalling point code
.LP
The point code of the signalling point in which the message
is originated.
.bp
.sp 1P
.LP
3.8
\fICall supervision message\fR
.sp 9p
.RT
.PP
The basic format of the \fIcall supervision\fR | message is shown in
Figure\ 14/Q.723.
.RT
.LP
.rs
.sp 13P
.ad r
\fBFigure\ 14/Q.723, (M), p.
.sp 1P
.RT
.ad b
.RT
.PP
The following codes are used in the fields of the call supervision message:
.LP
a)
Label: see \(sc\ 2
.LP
b)
Heading code H0 is coded 0110
.LP
c)
Heading code H1 contains signal codes as follows:
.LP
0000
answer signal, unqualified
.LP
0001
answer signal, charge
.LP
0010
answer signal, no charge
.LP
0011
clear\(hyback signal
.LP
0100
clear\(hyforward signal
.LP
0101
re\(hyanswer signal
.LP
0110
forward\(hytransfer signal
.LP
0111
calling party clear signal (national option)
.LP
1000
.LP
\ to
spare
.LP
1111
.sp 1P
.LP
3.9
\fICircuit supervision message\fR
.sp 9p
.RT
.PP
The basic format of the \fIcircuit supervision\fR | message is shown in
Figure\ 15/Q.723.
.RT
.LP
.rs
.sp 13P
.ad r
\fBFigure\ 15/Q.723, (M), p.
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.PP
The following codes are used in the fields of the circuit
supervision message:
.LP
a)
Label: see \(sc\ 2
.LP
b)
Heading code H0 is coded 0111
.LP
c)
Heading code H1 contains signal codes as follows:
.LP
0000
spare
.LP
0001
release\(hyguard signal
.LP
0010
blocking signal
.LP
0011
blocking\(hyacknowledgement signal
.LP
0100
unblocking signal
.LP
0101
unblocking\(hyacknowledgement signal
.LP
0110
continuity\(hycheck\(hyrequest signal
.LP
0111
reset\(hycircuit signal
.LP
1000
.LP
\ to
spare
.LP
1111
.sp 1P
.LP
3.10
\fICircuit group supervision message\fR
.sp 9p
.RT
.PP
The basic format of the circuit group supervision message is shown in Figure\
16/Q.723:
.RT
.LP
.rs
.sp 11P
.ad r
\fBFigure\ 16/Q.723, (M), p.
.sp 1P
.RT
.ad b
.RT
.PP
The following codes are used in the fields of the circuit group
supervision message:
.LP
a)
Label: see \(sc\ 2
.LP
The following interpretations apply to the CIC given in the label:
.LP
i)
If the range field is not coded all zero the CIC given in the label is
the first CIC within the circuit group or the first CIC within that part
of the circuit group.
.LP
ii)
If the range field is coded all zero (national
option) the CIC given in the label is a representative CIC within the circuit
group.
.LP
b)
Heading code H0 is coded 1000
.LP
c)
Heading code H1 contains message codes as follows:
.LP
0000
spare
.LP
0001
Maintenance oriented group blocking message
.LP
0010
Maintenance oriented group blocking\(hyacknowledging message
.LP
0011
Maintenance oriented group unblocking message
.LP
0100
Maintenance oriented group
unblocking\(hyacknowledgement message
.LP
0101
Hardware failure oriented group blocking message
.LP
0110
Hardware failure oriented group blocking\(hyacknowledge message
.LP
0111
Hardware failure oriented group unblocking message
.LP
1000
Hardware failure oriented group
unblocking\(hyacknowledgement message
.LP
1001
Circuit group reset message
.LP
1010
Circuit group reset\(hyacknowledgement message
.LP
1011
Software generated group blocking message (national option)
.LP
1100
Software generated group blocking\(hyacknowledgement
message (national option)
.LP
1101
Software generated group unblocking message
(national option)
.LP
1110
Software generated group unblocking\(hyacknowledgement message (national
option)
.LP
1111
spare
.bp
.LP
d)
Range: in principle, two different codings are
possible:
.LP
i)
not all zero: The message is related to a whole
circuit group or a part thereof, and includes a status field unless the
message is the circuit group reset message. The number of consecutive circuits
to be
handled is indicated by the value contained in the range field increased
by 1. The CIC of the first circuit to be handled is given in the label.
The number of circuits to be indicated is\ 2 (range value\ 1) to 256 (range
value\ 255).
.LP
ii)
all zero
.FS
Range value zero is only for national
use.
.FE
(national option): The message is related to a pre\(hydetermined circuit
group. No status field is included. In this case the circuit group is
addressed by means of a representative CIC within the circuit group.
.PP
\fINote\fR \ \(em\ In national networks, the range field may not be used
if only the concept of pre\(hydetermined circuit group applies.
.LP
e)
Status field
.LP
All circuit group supervision messages except the circuit
group reset message include a status field containing status indicator bits
when the range field is not coded all zero. The number of status indicator
bits is indicated by the value given in the range field increased by one.
.LP
The status field contains up to 256 one bit status
indicators. The first status indicator bit is related to the circuit indicated
by the CIC contained within the label, the second one is related to the
circuit address by the CIC contained in the label increased by\ 1.
.LP
.rs
.sp 12P
.ad r
\fBfigure\ 17/Q.723, (M), p.
.sp 1P
.RT
.ad b
.RT
.PP
The CIC of the last circuit concerned is obtained by adding the
value given in the range field to the CIC in the label. The status field
consists of an integral number of octets. Bits within the last octet that
are not used as status indicators are filled with zeros.
.PP
The status indicator bits are coded as follows:
.RT
.LP
\(em
in all group blocking messages (MGB, HGB, SGB)
.LP
1
blocking
.LP
0
no blocking
.LP
\(em
in all group blocking\(hyacknowledgement messages (MGB, HBA,
SBA)
.LP
1
blocking acknowledgement
.LP
0
no blocking acknowledgement
.LP
\(em
in all unblocking messages (MGU, HGU, SGU)
.LP
1
unblocking
.LP
0
no unblocking
.LP
\(em
in all group unblocking\(hyacknowledgement messages
(MUA, HUA, SUA)
.LP
1
unblocking acknowledgement
.LP
0
no unblocking acknowledgement
.LP
\(em
in the circuit group reset\(hyacknowledgement message (GRA)
.LP
1
blocking for maintenance reasons
.LP
0
no blocking for maintenance reasons
.bp
.sp 1P
.LP
3.11
\fICircuit network management messages\fR
.sp 9p
.RT
.PP
The following type of circuit network management message is
specified and identified by one of the heading codes\ H1. Unallocated H1\
codes in this message group are spare.
.RT
.sp 1P
.LP
3.11.1
\fIAutomatic congestion control information message\fR
.sp 9p
.RT
.PP
The basic format of the automatic congestion control (ACC)
information message is shown in Figure\ 18/Q.723:
.RT
.LP
.rs
.sp 8P
.ad r
\fBFigure\ 18/Q.723, (N), p.
.sp 1P
.RT
.ad b
.RT
.PP
The following codes are used in the fields of the automatic
congestion control information message.
.LP
a)
Label: see \(sc\ 2
.LP
b)
Heading code H0 is coded 1001
.LP
c)
Heading code H1 is coded 0001
.LP
d)
Message indicators
.LP
bits
B
A
ACC information
.LP
0
0
spare
.LP
0
1
congestion level 1
.LP
1
0
congestion level 2
.LP
1
1
spare
.LP
bits
HGFEDC
spare
.ce 1000
ANNEX\ A
.ce 0
.ce 1000
(to Recommendation Q.723)
.sp 9p
.RT
.ce 0
.ce 1000
\fBCharging messages\fR
.sp 1P
.RT
.ce 0
.LP
A.1
\fIIntroduction\fR
.sp 1P
.RT
.PP
The application of Signalling System No.\ 7 in national networks was recognized
from the beginning of the discussions about the signalling system. The
result of this can be found throughout the specifications especially in
those Recommendations dealing with the TUP. One of the points which is
particularly of interest for an Administration is the possibility of transfer
of charging information. Signalling System No.\ 7 allows for such a feature
for charging a calling subscriber by defining a specific charging message
as
indicated in \(sc\ 3.6.2. However, the detailed format, coding and related
procedures are not given, mostly because this matter is very dependent
on the circumstances within a specific national network. The following
examples
illustrate a particular implementation in a national network for telephony
without exclusion of other possible solutions.
.RT
.sp 1P
.LP
A.2
\fIStarting points\fR
.sp 9p
.RT
.PP
Before describing in detail the messages involved, a number of
starting points have to be adopted.
.RT
.LP
a)
The first No.\ 7 exchange performs metering according to all
possible tariffs.
.LP
b)
The determination of a particular tariff is performed in a
point somewhere in the network.
.LP
c)
The receipt of messages containing charging information
should be acknowledged within the call control procedures.
.LP
d)
At dedicated moments the actual charging should be
adapted.
.LP
e)
A variety of charging possibilities should be
available.
.bp
.PP
The effect of these starting points is:
.LP
a)
the actual generation of charging units according to a
particular tariff is always performed at the lowest level of the
national public telephone network (local exchange);
.LP
b)
the determination of tariffs for local and trunk calls is
carried out in the local exchange and for international calls in
the international exchange; however, also the use of a centre
for determination of all kinds of tariffs is possible;
.LP
c)
the transmission of charging information is assured at the
highest level of the call control procedures and possibly
inhibits call completion without receipt of charging
information;
.LP
d)
calls of long duration can be subject to different charging
rates;
.LP
e)
the application of charge free calls, specific charge on
answer, time dependent charging during a call, additional
(specific) charge during a call and a combination of these.
.sp 1P
.LP
A.3
\fIMessages and procedures\fR
.sp 9p
.RT
.PP
To meet all the above mentioned requirements a number of messages are defined.
.RT
.sp 1P
.LP
A.3.1
\fICharging message\fR
.sp 9p
.RT
.PP
This message has to be sent for any call, charge free or not. In
the procedure this is covered by the fact that the charging message has
to be received during call set up before receipt of the address complete
message.
.PP
If not, then the call should be cleared immediately.
.PP
The content of the message will vary depending on the actual tariff
and this is indicated by a number of indicators indicating the presence of
certain fields in the message.
.PP
Possible contents:
.RT
.LP
a)
charge band
.LP
The indication of a certain charge band should allow the
receiving exchange to charge a call according to a certain
tariff including possible switchover times to higher or lower
rates. This method results in a simple message but requires the
receiving exchange to have all the information available related
to all possible charge bands, national and international.
.LP
b)
explicit charging indication
.LP
In this case the message contains explicit indications of
details of the tariff viz.
.LP
\(em
number of charging units on answer (packet)
.LP
\(em
time dependent tariff(s)
.LP
\(em
possible switchover time.
.LP
This method results in a more complex message but does not require the
permanent storage of any charging information.
.sp 1P
.LP
A.3.2
\fIChange message\fR
.sp 9p
.RT
.PP
A consequence of the adoption of the method with explicit charging
indication (\(sc\ A.3.1\ b)) is the necessity to allow for tariff switchover
for
calls of very long duration or for calls which are answered just after the
switchover time given in the message described in \(sc\ A.3.1\ b). The
content of
such at message is rather simple because it only contains the new applicable
tariff and the actual switch\(hyover time.
.PP
The procedure to acknowledge the receipt of the message cannot be
found in the normal call control procedure, therefore an acknowledgement
message (see \(sc\ A.3.5) in the forward direction is used. If this acknowledgement
message is not received within a certain time, the change message has to
be
repeated.
.RT
.sp 1P
.LP
A.3.3
\fICollection charging\fR
.sp 9p
.RT
.PP
For a variety of reasons it might be necessary to charge a
subscriber during the call a certain amount. For this purpose a message
is used indicating the number of charging units related to the amount for
which the
subscriber has to be charged.
.PP
The procedure to assure the receipt of this message is the same as
described in \(sc\ A.3.2 above. A possible further collection charging message
should not be sent before receipt of the acknowledgement message and the
charging confirmation message (see \(sc\ A.3.4 charging confirmation).
.bp
.RT
.sp 1P
.LP
A.3.4
\fICharging confirmation\fR
.sp 9p
.RT
.PP
In relation with the message described in \(sc\ A.3.3 a message in the
forward direction is required indicating how many charging units actually
are charged to the subscriber. This number should match to the number given
in the collection charging message, otherwise it must be concluded that
for some
reason the order is not executed, e.g.,\ a certain service should now be
withheld to be furnished to the subscriber.
.PP
Again the procedure is the one as described in \(sc\ A.3.2 above but in
the opposite direction.
.RT
.sp 1P
.LP
A.3.5
\fIAcknowledgement\fR
.sp 9p
.RT
.PP
To acknowledge the receipt of the messages described in \(sc\(sc\ A.3.2,
A.3.3 and A.3.4, an acknowledgement message is used in both directions
only
indicating the receipt of the related message.
.RT
.LP
A.4
\fIFormats and codes\fR
.sp 1P
.RT
.sp 2P
.LP
A.4.1
\fICharging messages\fR
.sp 1P
.RT
.sp 1P
.LP
A.4.1.1
\fICharge band\fR
.sp 9p
.RT
.LP
.rs
.sp 8P
.ad r
\fBtableau ccitt 86010, (M), p.
.sp 1P
.RT
.ad b
.RT
.LP
\(em
Charge band
.LP
A charge indicates the combination of tariffs including
switch\(hyover times which is applicable for a certain period
(e.g., day or week).
.sp 1P
.LP
A.4.1.2
\fIExplicit charging indication\fR
.sp 9p
.RT
.LP
.rs
.sp 8P
.ad r
\fBtableau ccitt 86020, (M), p.
.sp 1P
.RT
.ad b
.RT
.LP
\(em
Message indicators
.LP
bit
A:
tariff indicator current tariff (A)
.LP
0
packet charging field and tariff indicators
current tariff (A) not present
.LP
1
packet charging field and tariff indicators
current tariff (A) present
.LP
bit
B:
tariff factor current tariff (A)
.LP
0
tariff factor field current tariff (A) not
present
.LP
1
tariff factor field current tariff (A) present
.bp
.LP
bit
C:
tariff indicator next tariff (B)
.LP
0
packet charging field and tariff indicators next tariff (B) not present
.LP
1
packet charging field and tariff indicators next tariff (B) present
.LP
bit
D:
tariff factor next tariff (B)
.LP
0
tariff factor field next tariff (B) not present
.LP
1
tariff factor field next tariff (B) present
.LP
bit
H\(hyE
spare
.LP
\(em
Packet charging field
.LP
0000
.LP
\ |
number of charging units on answer
.LP
1111
.LP
\(em
Tariff indicators
.LP
0000
tariff\ scale\ 0
(no time dependent tariff)
.LP
0001
tariff\ scale\ I
.LP
\ |
tariff\ scale\
|
every scale indicates a
certain step in seconds or parts thereof
.LP
1111
tariff\ scale\ XV
.LP
\(em
Tariff factors
.LP
If a call is charge free (A\ =\ B\ =\ C\ =\ D\ =\ 0) only the
message indicator octet is present.
.LP
If a call is charge free from the start but may become
chargeable (A\ =\ 1, B\ =\ 0, C\ =\ 1, D\ =\ 0/1), the packet charging
field for the
current tariff is 0000 and the tariff indicator for the current tariff
indicates scale\ 0.
.LP
If a call is chargeable from the start but may become charge free (A\
=\ 1, B\ =\ 0/1, C\ =\ 1, D\ =\ 0) the packet charging field for the next
tariff is\ 0000 and the tariff indicator for the next tariff indicates
scale\ 0. If a call is chargeable according to only one tariff (A\ =\ 1,
B\ =\ 0/1, C\ =\ 0,
D\ =\ 0), also the time indicator is not present in the message. The actual
tariff is determined by multiplication of the step indicated by the tariff
indicator with the tariff factor which gives then a specific charging unit
interval in seconds.
.LP
\(em
Time indicator
.LP
000000
spare
.LP
000001
00.30 h
.LP
000010
01.00 h
.LP
\ \ |
\ \ |
.LP
\ \ |
\ \ |
.LP
110000
24.00 h
.sp 1P
.LP
A.4.2
\fITariff change message\fR
.sp 9p
.RT
.LP
.rs
.sp 8P
.ad r
\fBtableau ccitt 86030, (M), p.
.sp 1P
.RT
.ad b
.RT
.LP
\(em
Message indicator
.LP
Bit
A:
tariff factor next tariff
.LP
0
tariff factor field next tariff not present
.LP
1
tariff factor field next tariff present
.LP
Bits
D\(hyB:
spare
.LP
\(em
Tariff indicator, tariff factor and time indicator: see
\(sc\ A.4.1.2
.bp
.sp 1P
.LP
A.4.3
\fICollection charging message\fR
.sp 9p
.RT
.LP
.rs
.sp 8P
.ad r
\fBtableau ccitt 86040, (M), p.
.sp 1P
.RT
.ad b
.RT
.PP
The collection field contains the number of charging units which
are to be charged to the calling subscriber. The field has a length of
8\ bits so a maximum of 256\ units is possible.
.RT
.sp 1P
.LP
A.4.4
\fICharging confirmation message\fR
.sp 9p
.RT
.LP
.rs
.sp 8P
.ad r
\fBtableau ccitt 86040 (?), (M), p.
.sp 1P
.RT
.ad b
.RT
.LP
\(em
Heading code H1
.LP
H1\ =\ 0101
confirmation of packet charging
.LP
H1\ =\ 0110
confirmation of collection charging
.LP
\(em
Charging unit field
.LP
Number of charging units which actually are charged
to the calling party
.sp 1P
.LP
A.4.5
\fIAcknowledgement message\fR
.sp 9p
.RT
.LP
.rs
.sp 8P
.ad r
\fBtableau ccitt 86050, (M), p.
.sp 1P
.RT
.ad b
.RT
.LP
\(em
Heading code H1
.LP
H1\ =\ 1000
acknowledgement receipt of tariff review,
collection charging or charging confirmation message
.bp
.sp 2P
.LP
\fBReferences\fR
.sp 1P
.RT
.LP
[1]
CCITT Recommendation \fICharacteristics of primary PCM multiplex\fR
\fIequipment operating at 2048\ kbit/s\fR , Rec.\ G.732.
.LP
[2]
CCITT Recommendation \fICharacteristics of 2048\(hykbit/s frame structure\fR
\fIfor use with digital exchanges\fR , Vol.\ III, Rec.\ G.734.
.LP
[3]
CCITT Recommendation \fISecond order PCM multiplex equipment operating\fR
\fIat 8448\ kbit/s\fR , Rec.\ G.744.
.LP
[4]
CCITT Recommendation \fICharacteristics of 8448\(hykbit/s frame structure\fR
\fIfor use with digital exchanges\fR , Rec.\ G.746.
.LP
[5]
CCITT Recommendation \fILanguage digit or discriminating digits\fR ,
Rec.\ Q.104.
.LP
[6]
CCITT Recommendation \fISignalling Connection Control Part\fR ,
Recs.\ Q.711\(hyQ.714.
.LP
.rs
.sp 42P
.sp 2P
.LP
\fBMONTAGE: RECOMMANDATION Q.724 SUR LE RESTE DE CETTE PAGE\fR
.sp 1P
.RT
.LP
.bp