Content for TS 23.292 Word version: 17.0.0

1… 4… 5… 7… 7.2… 7.3… 7.3.2.2… 7.3.2.2.4… 7.4… 7.4.2.2… 7.4.2.2.3… 7.4.2.2.7… 7.5… 7.6… 7.6.1.2.2.6… 7.6.1.2.3… 7.6.1.2.3.5… 7.6.1.2.3.6… 7.6.2… 7.6.2.7 7.6.2.8… 7.6.2.11… 7.6.3… 7.7… 7.7.2… 7.9… 7.9.2… 7.9.2.4 7.9.2.5 8… A… G… H… H.5… H.5.3…

7.3 Originations 7.3.1 Originating sessions that use PS media 7.3.2 Originating sessions that use CS media 7.3.2.1 Non ICS UE originating sessions that use CS media 7.3.2.1.1 Overview 7.3.2.1.2 Origination using I2 reference point 7.3.2.1.3 Origination when using an MSC Server
...

7.3 Originations p. 30

7.3.1 Originating sessions that use PS media p. 30

When the ICS UE has access to a PS network that supports the full duplex speech component of an IMS service, the originating IMS procedures (as described in clause 5.6 of TS 23.228) shall be used to set up the session. The S-CSCF shall insert the SCC AS in the IMS session path using originating initial filter criteria. The SCC AS shall be the first AS inserted into the session path.

7.3.2 Originating sessions that use CS media p. 30

7.3.2.1 Non ICS UE originating sessions that use CS media p. 30

7.3.2.1.1 Overview p. 30

Originating sessions that use CS media made by non ICS UEs that have been successfully registered in IMS by the MSC Server can utilize IMS service control. The non ICS UE initiates a standard CS originating session toward the MSC Server enhanced for ICS, which in turn can initiate an IMS originating session using the I2 reference point.

For these sessions, the MSC Server shall perform interworking between the I2 reference point and CS signalling (e.g. as described in TS 24.008). The MSC Server shall also control a CS-MGW using the Mc reference point to perform interworking between CS access bearers and RTP bearers on the Mb reference point. For emergency sessions, the MSC Server may perform existing MSC Server emergency call handling procedures or interworking with IMS as specified in clause 7.3.2.3.

For video call originating sessions that use CS media, the MSC Server enhanced for ICS shall also, after the multimedia connection is established, perform the video codec negotiation for the non ICS UE and set up the video media bearer based upon the procedures defined in TS 29.163 for 3GPP systems and based on procedures defined in 3GPP2 C.S0042 [38] for 3GPP2 systems.

The SCC AS shall be inserted in the IMS session path using the iFC.

7.3.2.1.2 Origination using I2 reference point p. 30

Figure 7.3.2.1.2-1 describes how IMS originations are performed via CS access for non ICS UE. This call flow also applies for an ICS UE CS origination with CS media without use of I1 and with use of an MSC server enhanced for ICS, as specified in clause 7.3.2.2.3.

Copy of original 3GPP image for 3GPP TS 23.292, Fig. 7.3.2.1.2-1: IMS Origination via CS Access for non ICS UE

Figure 7.3.2.1.2-1: IMS Origination via CS Access for non ICS UE
(⇒ copy of original 3GPP image)

Step 1.

The UE A sends a CS call setup message containing the B-party number to the MSC Server enhanced for ICS according to standard CS originating procedures.

Step 2.

The MSC Server sends an INVITE to the S-CSCF with the Request-URI set to the B-party number. If a GRUU is to be included as described in TS 23.228, then include a temporary-GRUU as the contact address if privacy has been requested or a public-GRUU if privacy has not been requested. The INVITE also contains SDP received from the CS-MGW. The MSC Server adds the User Location Information (e.g. CGI or SAI) and/or UE Time Zone Information to the INVITE. For a roaming user, when the Roaming Architecture for Voice over IMS with Local Breakout is supported according to clause 4.15a of TS 23.228, the MSC Server may, based on operator policy, add a reference to the preferred Transit and Roaming Function.

Step 3.

The S-CSCF performs standard service control execution procedures. Filter criteria direct the S-CSCF to send the INVITE to the SCC AS.

Step 4.

The SCC AS invokes a B2BUA, terminating the UE A Leg and originating the Remote Leg for presentation of an IMS session towards the B-party on behalf of UE A. The SCC AS creates an INVITE containing the SDP received in the CS Bearer Control Signalling Path, indicating CS voice or voice and video media. The INVITE request is routed from the SCC AS to the S-CSCF.

Step 5.

The S-CSCF continues with standard IMS originated session processing and routes the request onwards to the B-party.

Step 6.

Completion of the session and bearer control setup procedures. For video call, to complete the session and bearer setup, the specific handling as described in clause 7.3.2.1.1 applies.

7.3.2.1.3 Origination when using an MSC Server p. 31

Figure 7.3.2.1.3-1 describes how IMS originations are performed via CS access for non ICS UE attached to a legacy MSC or MSC-Server which has not been enhanced for ICS. This call flow also applies for an ICS UE CS origination with CS media without use of I1 and with use of an MSC server, as specified in clause 7.3.2.2.3.

Copy of original 3GPP image for 3GPP TS 23.292, Fig. 7.3.2.1.3-1: IMS Origination via CS Access for non ICS UE

Figure 7.3.2.1.3-1: IMS Origination via CS Access for non ICS UE
(⇒ copy of original 3GPP image)

Step 1.

The UE A originates a call in the CS domain to party-B according to standard origination procedures.

Step 2.

The MSC Server responds with a Call Proceeding message and begins to set up the CS Bearer Control Signalling Path.

Step 3.

The MSC-Server fetches an IP Multimedia Routing Number (IMRN) via IN (e.g. CAMEL) and routes the call towards the user's home IMS network using the IMRN via an MGCF.

Step 4.

The MGCF initiates an INVITE towards the I-CSCF in the home IMS of the originating ICS user.

Step 5.

The I-CSCF routes the INVITE based on one of the following standard procedures specified in "PSI based Application Server termination - direct and PSI based Application Server termination - indirect" procedures in TS 23.228 either directly to the SCC AS or via the S-CSCF.

Step 6.

When the INVITE arrives at the SCC AS, it invokes a B2BUA, terminating the UE A leg and originating the Remote Leg for presenting an IMS session towards the B-party on behalf of UE A. The SCC AS creates an INVITE containing the SDP received from MGCF, indicating CS voice or voice and video media. The original called number and the calling party number are used to setup the outgoing call leg to party-B in accordance with the AS origination procedure defined in clause 5.6.5 of TS 23.228. If required the SCC AS adds User Location Information (e.g. CGI or SAI) and/or UE Time Zone Information to the INVITE. The SCC AS sends the INVITE back to S-CSCF.

Step 7-8.

The S-CSCF sends the INVITE further for completion of the call toward the remote end. For video call, to complete the session and bearer setup, the specific handling as described in clause 7.3.2.1.1 applies.