7.5.10 Closed User Group (CUG)
29.1633GPPInterworking between the IP Multimedia (IM) Core Network (CN) subsystem and Circuit Switched (CS) networksTS
7.5.10.0 General
The protocol specification of the Closed User Group supplementary service is described in 3GPP TS 24.654 [101].
7.5.10.1 Interworking at the I-MGCF
If the I-MGCF supports the interworking of CUG supplementary service, the I-MGCF shall map between the SIP and ISUP messages in accordance with table 7.5.10.1.1.
Table 7.5.10.1.1: Mapping of SIP messages to ISUP messages
|
SIP Message |
ISUP Message |
|
INVITE request containing a XML cug body with CUG XML schema |
IAM containing the Closed user group interlock code Parameter and the closed user group call indicator of the Optional Forward Call Indicator Parameter |
If the MGCF supports the interworking of CUG supplementary service, the I-MGCF shall interwork the CUG XML schema with the ISUP Closed user group interlock code parameter and the Closed user group call indicator of the optional forward call indicator parameter in accordance with tables 7.5.10.1.2 and 7.5.10.1.3.
Table 7.5.10.1.2: Mapping of the SIP XML CUG Element to the ISUP closed usergroup interlock code parameter
|
CUG XML Element |
Source component value |
ISUP Closed user group interlock code Parameter |
derived value of parameter field |
|
networkIndicator |
networkIdentityType = 4 hexbinary coded digits (NOTE) |
"Network Identity" |
Octet 1 & Octet 2 including 4 binary coded digits derived from XML Network Identity |
|
cugInterlockBinaryCode |
sixteenbitType = 16 bit coded value |
"Binary Code" |
Octet 3 & Octet 4 including a 16 bit Binary Code derived from the XML Binary Code |
|
NOTE: ISUP Closed user group interlock code Parameter Octet 1 contains "Network Identity" (NI) digits 1 & 2 and Octet 2 contains "Network Identity" digits 3 & 4.The networkidentityType is filled with "Octet1 & Octet 2" = "NI digit 1, NI digit 2, NI digit 3, NI digit 4". Example: Digit 1=0, Digit 2=4, Digit 3=9, Digit 4=0 so the networkidentityType is encoded with "0490". |
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Table 7.5.10.1.3: Mapping of the SIP XML CUG Element to the ISUP closed user group call indicator included in the optional Forward Call Indicator Parameter
|
CUG XML Element |
Source component value |
ISUP "Optional Forward Call Indicator" Parameter |
derived value of parameter field |
|
cugCommunicationIndicator |
Type=00 |
"closed user group call" indicator |
non-CUG call |
|
Type=01 |
spare |
||
|
Type=10 |
closed user group call, outgoing access allowed |
||
|
Type=11 |
closed user group call, outgoing access not allowed |
If the I-MGCF supports the interworking of CUG supplementary service, then if an INVITE request with the MIME including a cug XML element is received and the terminating network is not supporting CUG, the I-MGCF shall behave as shown in table 7.5.10.1.4.
Table 7.5.10.1.4: Action at the I-MGCF with a PSTN/ISDN network without CUG capability
|
cugCommunicationIndicator in INVITE request |
Action at the I-MGCF |
|
Type=11 (CUG without outgoing access) |
Release the communication with 403 |
|
Type=10 (CUG with outgoing access) |
Treat the communication as an ordinary call (NOTE) |
|
Non-CUG |
Treat the communication as an ordinary call |
|
NOTE: The cugCommunicationIndicator shall not be mapped or if appropriate the CUG call indicator of the optional forward call indicator shall be set to non-CUG call. |
|
7.5.10.2 Interworking at the O-MGCF
If the MGCF supports the interworking of CUG supplementary service, the O-MGCF shall map between the SIP and ISUP messages in accordance with table 7.5.10.2.1
Table 7.5.10.2.1: Mapping of ISUP messages to SIP messages
|
ISUP Message |
SIP Message |
|
IAM containing the Closed user group interlock code Parameter and the closed user group call indicator of the Optional Forward Call Indicator Parameter |
INVITE request containing a XML cug body with CUG XML schema |
If the MGCF supports the interworking of CUG supplementary service, the MGCF shall interwork the CUG XML schema with the ISUP Closed user group interlock code parameter and the Closed user group call indicator of the optional forward call indicator parameter in accordance with tables 7.5.10.2.2 and table 7.5.10.2.3.
Table 7.5.10.2.2: Mapping of the ISUP closed usergroup interloccode to SIP XML CUG element
|
ISUP Closed user group interlock code Parameter |
Source component value |
CUG XML Element |
derived value of parameter field |
|
"Network Identity" |
Octet 1 & Octet 2 including 4 binary coded digits |
networkIndicator |
networkIdentityType = 4 hexbinary coded digits derived from Network Identity (NOTE) |
|
"Binary Code" |
Octet 3 & Octet 4 including a 16 bit Binary Code |
cugInterlockBinaryCode |
sixteenbitType = 16 bit coded value derived from Binary Code |
|
NOTE: ISUP Closed user group interlock code Parameter Octet 1 contains "Network Identity" (NI) digits 1 & 2 and Octet 2 contains "Network Identity" digits 3 & 4.The networkidentityType shall be filled with "Octet1 & Octet 2" = "NI digit 1, NI digit 2, NI digit 3, NI digit 4". Example: Digit 1=0, Digit 2=4, Digit 3=9, Digit 4=0 so the networkidentityType is encoded with "0490". |
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Table 7.5.10.2.3: Mapping of the ISUP Closed user group call indicator to SIP XML CUG element
|
ISUP Optional Forward Call Indicator Parameter |
Source component value |
CUG XML Element |
derived value of parameter field |
|
closed user group call indicator |
non-CUG call |
cugCommunicationIndicator |
Type=00 |
|
spare |
Type=01 |
||
|
closed user group call, outgoing access allowed |
Type=10 |
||
|
closed user group call, outgoing access not allowed |
Type=11 |
If the MGCF supports the interworking of CUG supplementary service, but the IMS is not supporting CUG, the procedures described in ITU Q.735.1 [42] shall apply if an INVITE request with the MIME body including a cug XML element is sent and the O-MGCF supports CUG supplementary service.