BEARER INDEPENDENT CALL CONTROL PROTOCOL (CS2) AND SIGNALLING
SYSTEM No.7 – ISDN USER PART GENERAL FUNCTIONS OF MESSAGES AND
This Recommendation describes the messages, parameters and the signalling information contained
within parameters used by the Bearer Independent Call Control (BICC) protocol and the ISDN user
part, and their functions.
1 Scope ......................................................................................................................2
2 References ...............................................................................................................2 3 Definitions ...............................................................................................................2 4 Abbreviations ..........................................................................................................3 5 Signalling messages .................................................................................................5 6 Signalling parameters ...............................................................................................8 7 Parameter information .............................................................................................14
1 Draft Recommendation Q.1902.2 (07/01)
This Recommendation describes the elements of signalling information used by the Bearer Independent Call Control protocol and the ISDN user part and their functions. The encoding of these elements, the format of the messages in which they are conveyed, their applicability to the two protocols, and an indication of whether or not they are for national use, are described in Recommendation Q.1902.3. Throughout this Recommendation where a message, a parameter or parameter information relates to either physical circuits controlled by the ISDN user part or the BICC protocol call instances the notation 'circuit/CIC' is used. Also, a generic term „node‟ is used to refer to signalling entities in either the ISUP (i.e. an exchange) or the BICC network (i.e. either an SN or an CMN) whenever a message, a parameter or parameter information is applicable to either.
The following ITU-T Recommendations, and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published.
 ITU-T Recommendation Q.1902.1 (2001), Bearer Independent Call Control protocol (CS2)
See Q.1902.1  for all the references used within this Recommendation.
See Recommendation Q.1902.1 .
2 Draft Recommendation Q.1902.2 (07/01)
APP Application Transport Parameter ASE Application Service Element ATII Application Transport Instruction Indicators
CCBS Completion of Calls to Busy Subscribers CCNR Completion of Calls on No Reply CCSS Call Completion Service Set-up DME Digital Multiplexing Equipment DNIC Data Network Identification Code ECT Explicit Call Transfer
GSN Gateway Serving Node
GVNS Global Virtual Network Service ID Identifier
IN Intelligent Network
ISC International Switching Centre LFB Look For Busy
MCID Malicious Call Identification MLPP Multi-level Precedence and Preemption MNIC Mobile Network Identification Code PDU Protocol Data Unit
QoR Query on Release
ROER Remote Operation Error
ROIV Remote Operation Invoke
RORJ Remote Operation Reject
RORS Remote Operation Result
SCCP Signalling Connection Control Part SCF Service Control Function
SLR Segmentation Local Reference SN Serving Node
UID User Interactive Dialogue
WGS-84 World Geodetic System 1984 For further abbreviations see Recommendation Q.1902.1 .
Table 1 defines the acronyms used for BICC and ISUP messages.
3 Draft Recommendation Q.1902.2 (07/01)
Table 1/Q.1902.2 - Message acronyms
Acronym Message ACM Address complete
APM Application transport BLA Blocking acknowledgement BLO Blocking
CCR Continuity check request CFN Confusion
CGB Circuit/CIC group blocking CGBA Circuit/CIC group blocking acknowledgement
CGU Circuit/CIC group unblocking CGUA Circuit/CIC group unblocking acknowledgement
CPG Call progress
CRG Charge information
CQM Circuit/CIC group query CQR Circuit/CIC group query response DRS Delayed release (reserved - used in 1988 version)
FAA Facility accepted
FAR Facility request
FOT Forward transfer
FRJ Facility reject
GRA Circuit/CIC group reset acknowledgement
GRS Circuit/CIC group reset IAM Initial address
IDR Identification request
IRS Identification response INF Information
INR Information request
LPA Loop back acknowledgement LOP Loop prevention
NRM Network resource management OLM Overload
PRI Pre-release information REL Release
RLC Release complete
RSC Reset circuit/CIC
SAM Subsequent address
SDM Subsequent directory number SGM Segmentation
UBA Unblocking acknowledgement UCIC Unequipped CIC
UPA User part available
UPT User part test
USR User-to-user information
4 Draft Recommendation Q.1902.2 (07/01)
5 Signalling messages
5.1 Address Complete Message (ACM): A message sent in the backward direction indicating
that all the address signals required for routeing the call to the called party have been received. 5.2 Answer message (ANM): A message sent in the backward direction indicating that the call has been answered. In semi-automatic working, this message has a supervisory function. In automatic working, this message is used in conjunction with charging information in order to: – start metering the charge to the calling subscriber (see Recommendation Q.28 ); and – start measurement of call duration for international accounting purposes (see
Recommendation E.260 ).
5.3 Application Transport message (APM): A message sent in either direction to convey
application information using the Application Transport mechanism.
5.4 Blocking message (BLO): A message sent only for maintenance purposes to the exchange
at the other end of a circuit, to cause an engaged condition 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 message must be capable of accepting incoming calls on the concerned circuit unless it has also sent a blocking message. Under certain conditions, a blocking message is also a proper response to a reset circuit message.
5.5 Blocking Acknowledgement message (BLA): A message sent in response to a blocking
message indicating that the circuit has been blocked.
5.6 Call Progress message (CPG): A message, sent in either direction during the set-up or
active phase of the call, indicating that an event, which is of significance, and should be relayed to the originating or terminating access, has occurred.
5.7 Charge information message (CRG): Information sent in either direction for accounting
and/or call charging purposes.
5.8 Circuit/CIC Group Blocking message (CGB): A message sent to the node to permit the
switching equipment or maintenance system to remove from (and return to) traffic a group of circuits/CICs. A node receiving a Circuit/CIC Group Blocking message must be able to accept incoming calls on the group of blocked circuits/CICs unless it has also sent a Circuit/CIC Group Blocking message.
5.9 Circuit/CIC Group Blocking Acknowledgement message (CGBA): A message sent in
response to a Circuit/CIC Group Blocking message to indicate that the requested group of circuits/CICs has been blocked.
5.10 circuit/CIC Group Reset message (GRS): A message sent to release an identified group of
circuits/CICs when, due to memory mutilation or other causes, it is unknown whether for example, a release or release complete message is appropriate for each of the circuits/CICs in the group. If at the receiving end a circuit/CIC is remotely blocked, reception of this message should cause that condition to be removed.
5.11 circuit/CIC Group Reset Acknowledgement message (GRA): A message sent in
response to a Circuit/CIC Group Reset message indicating that the requested group of circuits/CICs has been reset. The message also indicates the maintenance blocking state of each circuit/CIC. 5.12 Circuit/CIC Group Unblocking message (CGU): A message sent to the node to cause
cancellation in a group of circuits/CICs of a blocked condition invoked earlier by a Circuit/CIC Group Blocking message.
5 Draft Recommendation Q.1902.2 (07/01)
5.13 Circuit/CIC Group Unblocking Acknowledgement message (CGUA): A message sent in
response to a Circuit/CIC Group Unblocking message to indicate that the requested group of circuits/CICs has been unblocked.
5.14 Circuit/CIC group Query Message (CQM): A message sent on a routine or demand basis
to request the far-end node to give the state of all circuits/CICs in a particular range. 5.15 Circuit/CIC group Query Response message (CQR): A message sent in response to a
Circuit/CIC Group Query message to indicate the state of all circuits/CICs in a particular range. 5.16 Confusion message (CFN): A message sent in response to any message (other than a
confusion message) if the node does not recognize the message or detects a part of the message as being unrecognized.
5.17 Connect message (CON): A message sent in the backward direction indicating that all the address signals required for routeing the call to the called party have been received and that the call has been answered.
5.18 Continuity message (COT) (ISUP): A message sent in the forward direction indicating
whether or not there is continuity on the preceding circuit(s) as well as of the selected circuit to the following exchange, including verification of the communication path across the exchange with the specified degree of reliability.
5.18a Continuity message (COT) (BICC): A message sent in the forward direction indicating
that the establishment of the bearer is complete up to and including the SN sending the COT message.
5.19 Continuity Check Request message (CCR): A message sent by an exchange for a circuit
on which a continuity check is to be performed, to the exchange at the other end of the circuit, requesting continuity checking equipment to be attached.
5.20 Facility Accepted message (FAA): A message sent in response to a facility request
message indicating that the requested facility has been invoked.
5.21 Facility message (FAC): A message sent in either direction at any phase of the call to request an action at another node. The message is also used to carry the results, error or rejection of a previously requested action.
5.22 Facility Reject message (FRJ): A message sent in response to a facility request message to indicate that the facility request has been rejected.
5.23 Facility Request message (FAR): A message sent from a node to another node to request
activation of a facility.
5.24 Forward Transfer message (FOT): A message sent in the forward direction on
semi-automatic calls when the outgoing international exchange/GSN operator wants the help of an operator at the incoming international exchange/GSN. The message will normally serve to bring an assistance operator (see Recommendation Q.101) into the call if the call is automatically set up at the exchange/GSN. When the call is completed via an operator (incoming or delay operator) at the incoming international exchange/GSN, the message should preferably cause this operator to be recalled.
5.25 Identification Request message (IDR): A message sent in the backward direction to
request action regarding the malicious call identification supplementary service. 5.26 Identification Response message (IRS): A message sent in response to the identification
6 Draft Recommendation Q.1902.2 (07/01)
5.27 Information message (INF): A message sent to convey information in association with a
call, which may have been requested in an information request message.
5.28 Information Request message (INR): A message sent by a node to request information in
association with a call.
5.29 Initial Address message (IAM): A message sent in the forward direction to initiate seizure
of an outgoing circuit/CIC and to transmit number and other information relating to the routeing and handling of a call.
5.30 Loop back Acknowledgement message (LPA): A message sent in the backward direction
in response to a continuity check request message indicating that a loop (or transceiver in the case of a 2-wire circuit) has been connected.
5.31 Loop Prevention message (LOP): A message sent to convey information required by the
ECT supplementary service.
5.32 Network Resource Management message (NRM): A message sent in order to modify
network resources associated with a certain call. The message is sent along an established path in any direction in any phase of the call.
5.33 Overload Message (OLM): A message sent in the backward direction, on non-priority calls in response to an IAM, to invoke temporary trunk blocking of the circuit concerned when the exchange generating the message is subject to load control.
5.34 Pass-Along Message (PAM): A message that may be sent in either direction to transfer
information between two signalling points along the same signalling path as that used to establish a physical connection between those two points.
5.35 Pre-release Information message (PRI): A message to be used with the Release message
for the transport of information which cannot be sent in the Release message due to the compatibility rules (see Q.1902.4 for BICC and Q.764 for ISUP).
5.36 Release message (REL): A message sent in either direction to indicate that the circuit/CIC is being released due to the reason (cause) supplied and is ready to be put into the idle state on receipt of the Release Complete message. Where the call is to be redirected the message will also carry the redirection number.
5.37 Release Complete message (RLC): A message sent in either direction in response to the
receipt of a Release message, or if appropriate to a Reset Circuit message, when the circuit/CIC concerned has been brought into the idle condition.
5.38 Reset Circuit/CIC message (RSC): A message sent to release a circuit/CIC when, due to
memory mutilation or other causes, it is unknown whether for example, a Release or a Release Complete message is appropriate. If, at the receiving end, the circuit/CIC is remotely blocked, reception of this message should cause that condition to be removed.
5.39 Resume message (RES): A message sent in either direction indicating that the calling or called party, after having been suspended, is reconnected.
5.40 Segmentation Message (SGM): A message sent in either direction to convey an additional
segment of an overlength message.
5.41 Subsequent Address Message (SAM): A message that may be sent in the forward
direction following an initial address message, to convey additional called party number information.
7 Draft Recommendation Q.1902.2 (07/01)
5.42 Subsequent Directory Number message (SDM): A message that may be sent in the
forward direction following an Initial Address Message, to convey additional called party number information, when the called party number in the Initial Address Message was contained in the Called Directory Number parameter.
5.43 Suspend message (SUS): A message sent in either direction indicating that the calling or called party has been temporarily disconnected.
5.44 Unblocking message (UBL): A message sent to the exchange at the other end of a circuit to cancel, in that exchange, the engaged condition of the circuit caused by a previously sent blocking
or circuit group blocking message.
5.45 Unblocking Acknowledgement Message (UBA): A message sent in response to an
unblocking message indicating that the circuit has been unblocked. 5.46 Unequipped CIC message (UCIC): A message sent from one node to another when it receives a message on a circuit/CIC that is not provisioned for use. 5.47 User Part Available message (UPA): A message sent in either direction as a response to a user part test message, to indicate that the user part is available. 5.48 User Part Test message (UPT): A message sent in either direction to test the status of a user part marked as unavailable for a signalling point.
5.49 User-to-user information message (USR): A message to be used for the transport of user-to-user signalling independent of call control messages.
6 Signalling parameters
6.1 access delivery information: Information sent in the backward direction indicating that a SETUP message was generated at the destination access.
6.2 access transport: Information generated on the access side of a call and transferred transparently in either direction between originating and terminating local nodes. The information is
significant to both users and local nodes.
6.3 application transport parameter (APP): Information sent in either direction to allow the peer-to-peer communication of Application Transport mechanism user applications. 6.4 automatic congestion level: Information sent to the node to indicate that a particular level of congestion exists at the sending node.
6.5 backward call indicators: Information relating to the characteristics of the connection, signalling path and called party sent in the backward direction.
6.6 backward GVNS: Information sent in the backward direction used for a GVNS call to convey GVNS related information.
6.7 call diversion information: Information sent in the backward direction indicating the redirecting reason and the notification subscription option of the redirecting user. 6.8 call diversion treatment indicators: Information sent in the forward direction concerning treatment of call diversion.
6.9 call history information: Information sent in the backward direction to indicate the accumulated propagation delay of a connection.
8 Draft Recommendation Q.1902.2 (07/01)
6.10 call offering treatment indicators: Information sent in the forward direction concerning
treatment of call offering.
6.11 call reference: Information identifying a particular call.
6.12 call transfer number: Information sent in both directions to identify each of the users involved in a call transfer.
6.13 call transfer reference: Information used to convey a reference number associated with the ECT supplementary service.
6.14 called directory number: Information to indicate the directory number. The directory
number is a number in the national numbering scheme that is allocated to a customer for a telephony service.
6.15 called IN number: Information indicating the number which was received in the SSP as called party number in IAM and SAM messages.
6.16 called party number: Information to identify the called party.
6.17 calling geodetic location: Information that indicates the geodetic location of the calling party. The reference system for the coding is the World Geodetic System 1984, (WGS-84). The origin of the WGS-84 coordinate system is the geometric centre of the WGS-84 ellipsoid. The ellipsoid is constructed by the rotation of an ellipse around the minor axis that is oriented in the north-south direction. The rotation axis is the polar axis of the ellipsoid, and the plane orthogonal to it and including the centre of symmetry is the equatorial plane.
The relevant dimensions are as follows:
Major Axis (a) = 6 378 137 m
Minor Axis (b) = 6 356 752.314 m
Coordinates are then expressed in terms of longitude and latitude relevant to this ellipsoid. The range of longitude is -180？ to +180？, and the range of latitude is -90？ to +90？. 0？ longitude corresponds to
the Greenwich Meridian, and positive angles are to the East, while negative angles are to the West. 0？ latitude corresponds to the equator, and positive angles are to the North, while negative angles are to the South. Altitudes are defined as the distance between the ellipsoid and the point, along a line orthogonal to the ellipsoid.
6.18 Calling Party Geodetic Velocity Information: Information that indicates velocity
information associated with the Calling Party Geodetic Information.
6.19 calling party number: Information sent in the forward direction to identify the calling party. 6.20 calling party's category: Information sent in the forward direction indicating the category of the calling party and, in case of semi-automatic calls, the service language to be spoken by the incoming, delay and assistance operators.
6.21 carrier selection information: Information sent in the forward direction to indicate the
method (namely call per call or preselection) being used to invoke carrier selection.
6.22 cause indicators: Information sent in either direction indicating the reason for sending the message (e.g. release message).
6.23 CCNR possible indicator: Information sent in ACM (subscriber free)/CPG (alerting) to
indicate the possibility to invoke a possible succeeding CCNR service request.
9 Draft Recommendation Q.1902.2 (07/01)
6.24 CCSS: Information sent in an initial address message indicating that a call is a CCBS or a CCNR call as defined in the CCBS or CCNR supplementary service.
6.25 charged party identification: Information identifying the charged party, e.g. the account number.
6.26 circuit assignment map: Information sent in the forward direction to identify the circuits used for an N ！ 64 kbit/s connection.
6.27 circuit group supervision message type: Information sent in a Circuit Group Blocking or Unblocking message, indicating that blocking (unblocking) is maintenance oriented or hardware oriented.
6.28 CIC group supervision message type: Information sent in a CIC Group Blocking or
Unblocking message, indicating that blocking (unblocking) is maintenance oriented. 6.29 circuit/CIC state indicator: Information indicating the state of a circuit/CIC according to the sending node.
6.30 closed user group interlock code: Information uniquely identifying a closed user group within a network.
6.31 Coding Decoding Processing parameter: Information sent in the Initial Address message, in support of DME tandeming avoidance procedure. This parameter indicates whether the voice call is compressed and the type of voice compression used.
6.32 collect call request: Information sent in the forward direction indicating whether or not a call is a collect call.
6.33 conference treatment indicators: Information sent in both directions concerning treatment of a multi-party call.
6.34 connected number: Information sent in the backward direction to identify the connected party.
6.35 connection request: Information sent in the forward direction on behalf of the signalling connection control part requesting the establishment of an end-to-end connection. 6.36 continuity indicators (ISUP): Information sent in the forward direction indicating whether or not the continuity check on the outgoing circuit was successful. A continuity check successful indication also implies continuity of the preceding circuits and successful verification of the path across the exchange with the specified degree of reliability.
6.36a continuity indicators (BICC): Information sent in the forward direction indicating that the establishment of the bearer is complete up to and including the SN sending the COT message. 6.37 correlation id: Information used by the SCF for correlation with a previous connection (see Recommendations Q.1218 and Q.1228 - Definition of common data types). 6.38 display information: Information sent in either direction indicating a text string to be sent to the user.
6.39 echo control information: Indicators used to request activation and deactivation of echo control devices, and to respond to such requests.
6.40 end of optional parameters: The end of optional parameters field indicates that there are no more optional parameters in the message.
10 Draft Recommendation Q.1902.2 (07/01)