\fBInformation element format using escape for extension\fR
}
.TE
.nr PS 9
.RT
.ad r
\fBTableau 4\(hy3/Q.931 [2T63.931], p. 11\fR
.sp 1P
.RT
.ad b
.RT
.LP
.sp 5
.rs
.sp 16P
.ad r
\fBFigure 4\(hy8/Q.931 [T64.931], p. 12\fR
.sp 1P
.RT
.ad b
.RT
.LP
.sp 2
.sp 1P
.LP
4.5.2
\fIExtensions of codesets\fR
.sp 9p
.RT
.PP
There is a certain number of possible information element
identifier values using the formatting rules described in \(sc\ 4.5.1;
128 from the variable length information element format and at least 8
from the single octet information element format.
.PP
One value in the single octet format is specified for shift operations
described below. One other value in both the single octet and variable
format is reserved. This leaves at least 133\ information element identifier
values
available for assignment.
.bp
.PP
It is possible to expand this structure to eight codesets of at least 133\
information element identifier values each. One common value in the single
octet format is employed in each codeset to facilitate shifting from one
codeset to another. The contents of this Shift information element identifies
the codeset to be used for the next information element or elements. The
codeset in use at any given time is referred to as the \*Qactive codeset\*U. By
convention, codeset\ 0 is the initially active codeset.
.PP
Two codeset shifting procedures are supported: locking shift and
non\(hylocking shift.
.PP
Codeset 5 is reserved for information elements reserved for national use.
.PP
Codeset 6 is reserved for information elements specific to the local network
(either public or private).
.PP
Codeset 7 is reserved for user\(hyspecific information elements.
.PP
The coding rules specified in \(sc 4.5.1 shall apply for information
elements belonging to any active codeset.
.PP
Transitions from one active codeset to another (i.e., by means of the locking
shift procedure) may only be made to a codeset with a higher numerical
value than the codeset being left.
.PP
An information element belonging to codesets 5, 6, or 7, may appear
together with information elements belonging to codeset\ 0 (being the active
codeset) by using the non\(hylocking shift procedure (see\ \(sc\ 4.5.4).
.PP
A user of network equipment shall have the capability to recognize a Shift
information element and to determine the length of the following
information element, although the equipment need not be able to interpret
and act upon the content of the information element. This enables the equipment
to determine the start of a subsequent information element.
.PP
Codeset 7 information element shall be handled according to the
procedures for unrecognized information elements (see\ \(sc\ 5.8.7.1) by
the first exchange in the local network, unless allowed by a future service
definition, bilateral agreement, or provision is made to support this across
the local
network for a specific user.
.PP
Codeset 6 is reserved for information elements specific to the local network
(either public or private). As such they do not have significance
across the boundaries between local networks, or across a national, or
international boundary. Therefore, codeset\ 6 information elements shall be
handled according to the procedures for unrecognized information elements
(see\ \(sc\ 5.8.7.1) beyond local network boundary, unless allowed by bilateral
agreement.
.PP
Codeset 5 is reserved for information elements reserved for national use.
As such they do not have significance across an international boundary.
Therefore, codeset\ 5 information elements shall be handled according to the
procedures for unrecognized information elements (see\ \(sc\ 5.8.7.1) at
the first exchange beyond the international boundary, unless there are
bilateral
agreements to the contrary.
.RT
.sp 1P
.LP
4.5.3
\fILocking shift procedure\fR
.sp 9p
.RT
.PP
The locking shift procedure employs an information element to
indicate the new active codeset. The specified codeset remains active until
another locking shift information element is encountered which specifies the
use of another codeset. For example, codeset\ 0 is active at the start of
message content analysis. If a locking shift to codeset\ 5 is encountered,
the next information elements will be interpreted according to the information
element identifiers assigned in codeset\ 5, until another shift information
element is encountered.
.PP
This procedure is used only to shift to a higher order codeset than
the one being left.
.PP
The
locking shift
is valid only within that message which
contains the locking Shift information element. At the start of every message
content analysis, the active codeset is codeset\ 0.
.PP
The locking Shift information element uses the single octet
information element format and coding shown in Figure\ 4\(hy9/Q.931
and Table\ 4\(hy4/Q.931.
.bp
.RT
.LP
.rs
.sp 16P
.ad r
\fBFigure 4\(hy9/Q.931 [T65.931], p. 13\fR
.sp 1P
.RT
.ad b
.RT
.ce
\fBH.T. [T66.931]\fR
.ce
TABLE\ 4\(hy4/Q.931
.ce
\fBLocking Shift information
.ce
element\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
lw(228p) .
.TE
.nr PS 9
.RT
.ad r
ne
\fBFigure 4\(hy4/Q.931 [T66.931], p. 14\fR
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
4.5.4
\fINon\(hylocking shift procedure\fR
.sp 9p
.RT
.PP
The non\(hylocking shift procedure provides a temporary shift to the specified
lower or higher codeset. The non\(hylocking shift procedure uses a
single octet information element to indicate the codeset to be used to
interpret the next single information element. After the interpretation
of the next single information element, the active codeset is again used
for
interpreting any following information elements. For example, codeset\ 0 is
active at the beginning of message content analysis. If a non\(hylocking
shift to codeset\ 6 is encountered, only the next information element is
interpreted
according to the information element identifiers assigned in codeset\ 6.
After this information element is interpreted, codeset\ 0 will again be
used to
interpret the following information elements. A non\(hylocking Shift information
element indicating the current codeset shall not be regarded as an error.
.bp
.PP
A locking Shift information element shall not follow directly on a
non\(hylocking Shift information element. If this combination is received, it
shall be interpreted as though a locking Shift information element only had
been received.
.PP
The non\(hylocking Shift information element uses the single octet
information element format and coding shown in Figure\ 4\(hy10/Q.931 and
Table\ 4\(hy5/Q.931.
.RT
.LP
.rs
.sp 15P
.ad r
\fBFigure 4\(hy10/Q.931 [T67.931], p. 15\fR
.sp 1P
.RT
.ad b
.RT
.LP
.sp 5
.ce
\fBH.T. [T68.931]\fR
.ce
TABLE\ 4\(hy5/Q.931
.ce
\fBNon\(hylocking Shift information element\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
lw(228p) .
.TE
.nr PS 9
.RT
.ad r
ne
\fBTableau 4\(hy5/Q.931 [T68.931], p. 16\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
4.5.5
\fIBearer capability\fR
.sp 9p
.RT
.PP
The purpose of the Bearer capability information element is to
indicate a requested Recommendation\ I.231\ [6] bearer service to be provided
by the network. It contains only information which \fImay\fR be used by
the network
(see Annex\ L). The use of the bearer capability information element in
relation to compatibility checking is described in Annex\ B.
.PP
The Bearer capability information element is coded as shown in
Figure\ 4\(hy11/Q.931 and Table\ 4\(hy6/Q.931.
.PP
Examples of the coding of the Bearer capability information element is
shown in Annex\ H.
.PP
No default bearer capability may be assumed by the absence of this
information element.
.PP
The maximum length of this information element is 13\ octets when CCITT
standard coding is used.
.PP
\fINote\fR \ \(em\ Future extensions to the codings of the Bearer capability
information element should not be in conflict with the currently defined
coding of the Low layer compatibility information element (see\ \(sc\ 4.5.18).
.RT
.sp 1P
.LP
4.5.6
\fICall identity\fR
.sp 9p
.RT
.PP
The purpose of the Call identity information element is to identify the
suspended call. The call identity provided by the user is guaranteed by
the network to be unique over the user\(hynetwork interface on which the
user
resides. The call identity is assigned at the start of the call suspension,
and is available for re\(hyuse after the resume procedure has completed
successfully.
.PP
The Call identity information element is coded as shown in
Figure\ 4\(hy12/Q.931.
.PP
The default maximum length of this information element is ten
octets.
.RT
.sp 1P
.LP
4.5.7
\fICall state\fR
.sp 9p
.RT
.PP
The purpose of the Call state information element is to describe
the current status of a call, (see\ \(sc\ 2.1) or an access connection
(see\ \(sc\ 2.2) or a global interface state (see\ \(sc\ 2.4).
.PP
The Call state information element is coded as shown in
Figure 4\(hy13/Q.931 and Table\ 4\(hy7/Q.931.
.PP
The maximum length of this information element is three octets when
CCITT standard coding is used.
.RT
.sp 1P
.LP
4.5.8
\fICalled party number\fR
.sp 9p
.RT
.PP
The purpose of the Called party number information element is to
identify the called party of a call.
.PP
The Called party number information element is coded as shown in
Figure 4\(hy14/Q.931 and Table\ 4\(hy8/Q.931.
.PP
The maximum length of this information element is network
dependent.
.RT
.sp 1P
.LP
4.5.9
\fICalled party subaddress\fR
.sp 9p
.RT
.PP
The purpose of the Called party subaddress information
element is to identify the subaddress of the called party of a call. For the
definition of subaddress see Recommendation\ I.330\ [18].
.PP
The Called party subaddress is coded as shown in Figure 4\(hy15/Q.931
and Table 4\(hy9/Q.931.
.PP
The maximum length of this information element is 23 octets.
.bp
.RT
.LP
.rs
.sp 47P
.ad r
\fBFigure 4\(hy11/Q.931 + Notes [T69.931], p. 17\fR
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [T70.931]\fR
.ce
TABLE\ 4\(hy6/Q.931\ (Sheet\ 1\ of\ 8)
.ce
\fBBearer capability information element\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
lw(228p) .
\fICoding standard (octet 3):\fR
Bits 7\ \ 6 0\ \ 0 CCITT standardized coding as described below
0\ \ 1 reserved for other international standards (Note)
1\ \ 0 national standard (Note)
{
1\ \ 1
standard defined for the network (either public or private)
present on the network side of the interface (Note)
}
.TE
.LP
\fINote\fR
\ \(em\ These other coding standards should be used only when the
desired bearer capability can not be represented with the CCITT\(hystandardized
coding.
}
.TS
center box ;
lw(228p) .
\fIInformation transfer capability (octet 3)\fR
Bits 5\ \ 4\ \ 3\ \ 2\ \ 1
0\ \ 0\ \ 0\ \ 0\ \ 0 speech
0\ \ 1\ \ 0\ \ 0\ \ 0 unrestricted digital information
0\ \ 1\ \ 0\ \ 0\ \ 1 restricted digital information
1\ \ 0\ \ 0\ \ 0\ \ 0 3.1 kHz audio
1\ \ 0\ \ 0\ \ 0\ \ 1 7 kHz audio
1\ \ 1\ \ 0\ \ 0\ \ 0 Video
All other values are reserved.
\fITransfer mode (octet 4)\fR
Bits 7\ \ 6
0\ \ 0 circuit mode
1\ \ 0 packet\(hymode
All other values are reserved.
.TE
.nr PS 9
.RT
.ad r
\fBTableau 4\(hy6/Q.931 (feuillet 1 sur 8) [T70.931], p. 18\fR
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 17P
.ad r
BLANC
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [T71.931]\fR
.ce
TABLE\ 4\(hy6/Q.931\ (Sheet\ 2\ of\ 8)
.ce
\fBBearer capability information element\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
lw(228p) .
\fIInformation transfer rate (octets 4 and 4b, bits 5 to 1)\fR
Bits 5\ \ 4\ \ 3\ \ 2\ \ 1
\fICircuit mode\fR
\fIPacket\(hymode\fR
0\ \ 0\ \ 0\ \ 0\ \ 0 \(em This code shall be used for packet mode calls
1\ \ 0\ \ 0\ \ 0\ \ 0 64 kbit/s
\(em 1\ \ 0\ \ 0\ \ 0\ \ 1
2 \(mu 64 kbit/s \(em 1\ \ 0\ \ 0\ \ 1\ \ 1
384 kbit/s \(em 1\ \ 0\ \ 1\ \ 0\ \ 1
1536 kbit/s \(em 1\ \ 0\ \ 1\ \ 1\ \ 1
1920 kbit/s \(em
All other values are reserved.
.TE
.LP
\fINote 1\fR
\ \(em\ When octet 4b is omitted, the bearer capability is
bidirectional symmetric at the information transfer rate specified in octet\ 4. When octet 4b is included, the information transfer rate in octet\ 4 refers to the origination \(ra destination direction.
.LP
\fINote 2\fR
\ \(em\ When the information transfer rate 2 \(mu 64 kbit/s is used, the
coding of octets\ 3 and\ 4 refer to both 64\ kbit/s channels.
.TS
box center ;
lw(228p) .
\fIStructure (octet 4a)\fR
Bits 7\ \ 6\ \ 5
0\ \ 0\ \ 0 default (see Note 1)
0\ \ 0\ \ 1 8 kHz integrity (Note 2)
1\ \ 0\ \ 0 service data unit integrity
1\ \ 1\ \ 1 unstructured
.TE
.LP
\fINote 1\fR
\ \(em\ If octet 4a is omitted, or the structure field is coded
\*Q000\*U, then the value of the structure attribute is according to the
following:
.TS
center box ;
lw(228p) .
\fITransfer mode\fR
\fITransfer capability\fR
\fIStructure\fR
circuit speech 8 kHz integrity
circuit unrestricted digital 8 kHz integrity
circuit restricted digital 8 kHz integrity
circuit audio 8 kHz integrity
circuit video 8 kHz integrity
packet unrestricted digital service data unit integrity
.TE
.LP
\fINote 2\fR
\ \(em\ When the information transfer rate 2 \(mu 64 kbit/s is
used, 8\ kHz integrity with Restricted Differential Time Delay (RDTD) is
offered.
.nr PS 9
.RT
.ad r
\fBTableau 4\(hy6/Q.931 (feuillet 2 sur 8) [T71.931], p. 19\fR
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 12P
.ad r
BLANC
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [T72.931]\fR
.ce
TABLE\ 4\(hy6/Q.931\ (Sheet\ 3\ of\ 8)
.ce
\fBBearer capability information element\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
lw(228p) .
\fIConfiguration (octet 4a)\fR
Bits 4\ \ 3
0\ \ 0 point\(hyto\(hypoint
All other values are reserved.
.TE
.LP
\fINote\fR
\ \(em\ If octet 4a is omitted, the configuration is assumed to be
point\(hyto\(hypoint.
.TS
center box ;
lw(228p) .
\fIEstablishment (octet 4a)\fR
Bits 2\ \ 1
0\ \ 0 demand
All other values are reserved.
.TE
.LP
\fINote\fR
\ \(em\ If octet 4a is omitted, the method of establishment is
assumed to be \*Qdemand\*U.
.LP
\fISymmetry (octet 4b)\fR
Bits 7\ \ 6
0\ \ 0 bidirectional symmetric
All other values are reserved.
.LP
\fINote\fR
\ \(em\ If octet 4b is omitted, bidirectional symmetric is
assumed.
.nr PS 9
.RT
.ad r
\fBTableau 4\(hy6/Q.931 (feuillet 3 sur 8) [T72.931], p. 20\fR
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 22P
.ad r
BLANC
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [T73.931]\fR
.ce
TABLE\ 4\(hy6/Q.931\ (Sheet\ 4\ of\ 8)
.ce
\fBBearer capability information element\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.LP
\fIUser information layer 1 protocol (octet 5)\fR
Bits 5\ \ 4\ \ 3\ \ 2\ \ 1
.LP
0\ \ 0\ \ 0\ \ 0\ \ 1
CCITT standardized rate adaption V.110/X.30. This
implies the presence of octet 5a and optionally octets 5b, 5c and 5d as
defined below.
.LP
0\ \ 0\ \ 0\ \ 1\ \ 0
Recommendation G.711 \(*m\(hylaw [10]
.LP
0\ \ 0\ \ 0\ \ 1\ \ 1
Recommendation G.711 A\(hylaw [10]
.LP
0\ \ 0\ \ 1\ \ 0\ \ 0
Recommendation G.721 [11] 32 kbit/s ADPCM and
Recommendation I.460
.LP
0\ \ 0\ \ 1\ \ 0\ \ 1
Recommendations G.722 [12] and G.725 [35] 7 kHz audio
.LP
0\ \ 0\ \ 1\ \ 1\ \ 0
Recommendation H.261 [13] for 384 kbit/s video
.LP
0\ \ 0\ \ 1\ \ 1\ \ 1
Non\(hyCCITT standardized rate adaption. This implies
the presence of octet 5a and, optionally, octets 5b, 5c and 5d. The use
of this code point indicates that the user rate specified in octet 5a is
defined in accordance with the non\(hyCCITT standardized rate adoption scheme.
Additionally, octets 5b, 5c and 5d, if present, are defined consistent
with the specified rate adoption.
.LP
0\ \ 1\ \ 0\ \ 0\ \ 0
CCITT standardized rate adaption V.120 [9]. This
implies the presence of octets 5a and 5b as defined below, and optionally
octets\ 5c and\ 5d.
.LP
0\ \ 1\ \ 0\ \ 0\ \ 1
CCITT standardized rate adaption X.31 [14] HDLC flag
stuffing.
.LP
All other values are reserved.
.LP
\fINote\fR
\ \(em\ If the transfer mode is \*Qcircuit mode\*U, and if the
information transfer capability is \*Qunrestricted digital information\*U or
\*Qrestricted digital information\*U, and if the user information layer 1 protocol is not to be identified to the network, octet 5 shall be omitted. If
the transfer mode is packet mode, octet 5 may be omitted. Otherwise, octet\ 5
shall be present.
.LP
\fISynchronous/asynchronous (octet 5a)\fR
Bit
7
.LP
0
Synchronous
.LP
1
Asynchronous
.LP
\fINote\fR
\ \(em\ Octets 5b\(hy5d may be omitted in case of synchronous user
rates.
.LP
\fINegotiation (octet 5a)\fR
.LP
Bit
6
.LP
0
In\(hyband negotiation not possible
.LP
1
In\(hyband negotiation possible
.LP
\fINote\fR
\ \(em\ See Recommendations V.110 [7] and
X.30 [8].
.nr PS 9
.RT
.ad r
\fBTableau 4\(hy6/Q.931 (feuillet 4 sur 8) [T73.931], p. 21\fR
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 10P
.ad r
BLANC
.ad b
.RT
.LP
.bp
.ce
\fBH.T. [T74.931]\fR
.ce
TABLE\ 4\(hy6/Q.931\ (Sheet\ 5\ of\ 8)
.ce
\fBBearer capability information element\fR
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.LP
\fIUser rate (octet 5a)\fR
.LP
Bits
5\ \ 4\ \ 3\ \ 2\ \ 1
.LP
0\ \ 0\ \ 0\ \ 0\ \ 0
rate is indicated by E\(hybits specified in Recommendation
I.460 [15]
.LP
0\ \ 0\ \ 0\ \ 0\ \ 1
0.6 kbit/s Recommendations V.6 [16] and X.1 [17]
.LP
0\ \ 0\ \ 0\ \ 1\ \ 0
1.2 kbit/s Recommendation V.6
.LP
0\ \ 0\ \ 0\ \ 1\ \ 1
2.4 kbit/s Recommendations V.6 and X.1
.LP
0\ \ 0\ \ 1\ \ 0\ \ 0
3.6 kbit/s Recommendation V.6
.LP
0\ \ 0\ \ 1\ \ 0\ \ 1
4.8 kbit/s Recommendations V.6 and X.1
.LP
0\ \ 0\ \ 1\ \ 1\ \ 0
7.2 kbit/s Recommendation V.6
.LP
0\ \ 0\ \ 1\ \ 1\ \ 1
8 kbit/s Recommendation I.460
.LP
0\ \ 1\ \ 0\ \ 0\ \ 0
9.6 kbit/s Recommendations V.6 and X.1
.LP
0\ \ 1\ \ 0\ \ 0\ \ 1
14.4 kbit/s Recommendation V.6
.LP
0\ \ 1\ \ 0\ \ 1\ \ 0
16 kbit/s Recommendation I.460
.LP
0\ \ 1\ \ 0\ \ 1\ \ 1
19.2 kbit/s Recommendation V.6
.LP
0\ \ 1\ \ 1\ \ 0\ \ 0
32 kbit/s Recommendation I.460
.LP
0\ \ 1\ \ 1\ \ 1\ \ 0
48 kbit/s Recommendations V.6 and X.1
.LP
0\ \ 1\ \ 1\ \ 1\ \ 1
56 kbit/s Recommendation V.6
.LP
1\ \ 0\ \ 1\ \ 0\ \ 1
0.1345 kbit/s Recommendation X.1
.LP
1\ \ 0\ \ 1\ \ 1\ \ 0
0.100 kbit/s Recommendation X.1
.LP
1\ \ 0\ \ 1\ \ 1\ \ 1
0.075/1.2 kbit/s Recommendations V.6 and X.1 (Note)
.LP
1\ \ 1\ \ 0\ \ 0\ \ 0
1.2/0.075 kbit/s Recommendations V.6 and X.1 (Note)
.LP
1\ \ 1\ \ 0\ \ 0\ \ 1
0.050 kbit/s Recommendations V.6 and X.1
.LP
1\ \ 1\ \ 0\ \ 1\ \ 0
0.075 kbit/s Recommendations V.6 and X.1
.LP
1\ \ 1\ \ 0\ \ 1\ \ 1
0.110 kbit/s Recommendations V.6 and X.1
.LP
1\ \ 1\ \ 1\ \ 0\ \ 0
0.150 kbit/s Recommendations V.6 and X.1
.LP
1\ \ 1\ \ 1\ \ 0\ \ 1
0.200 kbit/s Recommendations V.6 and X.1
.LP
1\ \ 1\ \ 1\ \ 1\ \ 0
0.300 kbit/s Recommendations V.6 and X.1
.LP
1\ \ 1\ \ 1\ \ 1\ \ 1
12 kbit/s Recommendation V.6
.LP
All other values are reserved.
.LP
\fINote\fR
\ \(em\ The first rate is the transmit rate in the forward direction of the call. The second rate is the transmit rate in the backward
direction of the call.
.LP
\fIOctet 5b for V.110/X.30 rate adaption\fR
.LP
\fIIntermediate rate (octet 5b)\fR
.LP
Bits
7\ \ 6
.LP
0\ \ 0
Not used
.LP
0\ \ 1
8 kbit/s
.LP
1\ \ 0
16 kbit/s
.LP
1\ \ 1
32 kbit/s
.LP
\fINetwork independent clock (NIC) on transmission (Tx) (octet 5b)\fR
\fI(Note 1)\fR
.LP
Bit
5
.LP
0
Not required to send data with network independent clock
.LP
1
Required to send data with network independent clock
.LP
\fINote 1\fR
\ \(em\ Refers to transmission in the forward direction of the
call.
.LP
}
.LP
\ \(em\ See Recommendations V.110 and X.30.
}
.RT
.ad r
\fBTableau 4\(hy6/Q.931 (feuillet 5 sur 8) [T74.931], p. 22\fR