9 Interaction with supplementary services

22.2793GPPCombined Circuit Switched (CS) and IP Multimedia Subsystem (IMS) sessionsStage 1TS

The current section lists the supplementary services as specified in 3GPP TS 22.004 [4].

9.1 Line Identification

9.1.1 Calling Line Identity Presentation (CLIP)

When CLIP is used in conjunction with a combinational service, it shall function as specified for CS voice and data calls.

If the called party does not subscribe to CLIP or the CLI is not available, then the called party’s UE may treat an incoming IMS session as an independent IMS session and the called party may establish an independent IMS session with the calling party.

9.1.2 Calling Line Identity Restriction (CLIR)

Existing CLIR rules apply, even if this results in the called party being unable to establish a combinational call.

If a calling party uses CLIR when establishing a CS call, either by subscription or per call basis, and the called party does not have CLIR override, then the called party’s UE may treat an incoming IMS session as an independent IMS session and the called party may establish an independent IMS session with the calling party.

If the CLI of the calling party is restricted as a result of CLIR, then the calling party’s UE or the network shall ensure that the Public User Identity of the calling party is also restricted when establishing an outgoing IMS session associated with this CS call and when responding to an incoming IMS session associated with this CS call.

9.1.3 Connected Line Identification Presentation (COLP)

When COLP is used in conjunction with a combinational service, it shall function as specified for CS voice and data calls.

If the calling party does not subscribe to COLP or the COL is not available, then the calling party’s UE may use the called party number of the CS call, as provided by the UE to the network, to correlate an incoming IMS session with the CS call and to establish an IMS session associated with the CS call.

9.1.4 Connected Line Identification Restriction (COLR)

Existing COLR rules apply, even if this results in the calling party being unable to establish a combinational call.

If the called party subscribes to COLR and the calling party does not have COLR override, then the calling party’s UE may use the called party number of the CS call, as provided by the UE to the network, to correlate an incoming IMS session with the CS call and to establish an IMS session associated with the CS call.

If the COL of the called party is restricted as a result of COLR, then the called party’s UE or the network shall ensure that the Public User Identity of the called party is also restricted when establishing an outgoing IMS session associated with this CS call and when responding to an incoming IMS session associated with this CS call.

9.2 Name Identification

9.2.1 Calling Name Presentation (CNAP)

When CNAP is used in conjunction with a combinational service, it shall function as specified for CS calls.

9.3 Call Forwarding

9.3.1 Call Forwarding Unconditional (CFU)

Call forwarding unconditional shall not prevent the calling party or the called party from adding an IMS session to the CS call. Refer to the clause on Line Identification for the usage of the CLI and COL for establishing an IMS session associated with the CS call and for correlating an incoming IMS session with the CS call.

9.3.2 Call Forwarding on Busy (CFB)

Refer to CFU.

9.3.3 Call Forwarding on No Reply (CFNRY)

Refer to CFU.

9.3.4 Call Forwarding on Not Reachable (CFNRC)

Refer to CFU.

9.3.5 Call Deflection (CD)

Refer to CFU.

9.4 Call Offering

9.4.1 Explicit Call Transfer (ECT)

At the moment that the subscriber invokes ECT, she may have an IMS session ongoing with either or both of the CS call parties. The user may keep or terminate these IMS sessions when ECT is invoked. The two CS call parties that are in speech connection after the invocation of ECT, have not exchanged Radio Network and Terminal capabilities with one another. Neither are these two call parties aware of one another’s Line Identification. These parties are therefore not capable of initiating IMS sessions, associated with the CS call.

9.5 Call Completion

9.5.1 Call Waiting (CW)

When a second CS call arrives during an ongoing combinational call, the IMS session of the ongoing combinational call shall not be affected. When the user decides to place the ongoing CS call on hold and accept the second CS call, then the rules as specified for Call Hold apply for the ongoing CS call that is placed on hold. When the incoming, waiting CS call is accepted, the calling party’s UE and called party’s UE may exchange terminal capability and radio network capability. An IMS session may be established associated with the second CS call, when that CS call is accepted. The IMS session(s) for the second CS call may run concurrently with the IMS session(s) for the CS call that is on hold.

9.5.2 Call Hold (CH)

When a user places a CS call on hold, the user may decide to suspend an IMS session associated with that CS call, or to terminate the IMS session. When a held CS call is resumed, an associated IMS session that was suspended when that CS call was placed on hold, may be resumed. The user may decide whether new IMS sessions may be created for a CS call when that CS call is currently in the held state.

For the second CS call that may be established or accepted when a first CS call is placed on hold, the calling party’s UE and called party’s UE may exchange terminal capability and radio network capability. An IMS session may be established associated with the second CS call, when that second call is active.

9.5.3 Call Completion to Busy Subscriber (CCBS)

Not part of the scope of the present specification.

9.5.4 Multi Call (MC)

Not part of the scope of the present specification.

9.6 Multi Party

9.6.1 Multi Party call (MPTY)

Not part of the scope of the present specification.

9.7 Community of Interest

9.7.1 Closed User Group (CUG)

No impact. When the establishment of an outgoing CS call or the acceptance of a CS incoming call is barred due to CUG, that shall not affect the calling or called party’s ability to establish IMS sessions with the other party. However, these IMS sessions will not be considered "combinational".

9.8 Charging

9.8.1 Advice of Charge – Information (AOCI)

When AOCI is used in conjunction with a combinational service, it shall function as specified for CS calls and packet data service.

9.8.2 Advice of charge – Charge (AOCC)

Refer to AOCI.

9.9 Additional Info Transfer

9.9.1 User-to-User Signalling service 1 (UUS1)

When UUS1 is used in conjunction with a combinational service, it shall function as specified for CS voice and data calls.

9.9.2 User-to-User Signalling service 2 (UUS2)

When UUS2 is used in conjunction with a combinational service, it shall function as specified for CS voice and data calls.

9.9.3 User-to-User Signalling service 3 (UUS3)

When UUS3 is used in conjunction with a combinational service, it shall function as specified for CS voice and data calls.

9.10 Call Barring

9.10.1 Barring of All Outgoing Calls (BAOC)

When the establishment of an outgoing CS call is barred due to BAOC, that shall not affect the calling party’s ability to establish IMS sessions with the other party. However, these IMS sessions will not be considered "combinational".

9.10.2 Barring of Outgoing International Calls (BOIC)

Refer to BAOC.

9.10.3 Barring of Outgoing International Calls except to HPLMN country (BOIC-exHc)

Refer to BAOC.

9.10.4 Barring of All Incoming Calls (BAIC)

When the acceptance of an incoming CS call is barred due to BAIC, that shall not affect the called party’s ability to establish IMS sessions with the other party. However, these IMS sessions will not be considered "combinational".

9.10.5 Barring of All Incoming Calls when roaming outside HPLMN country (BICROAM)

Refer to BAIC.

9.11 Call Priority

9.11.1 Enhanced Multi Level Precedence Pre-emption (EMLPP)

When a CS call cannot be established due to a lower precedence this shall not affect the user’s ability to establish IMS sessions to another party. However, these IMS sessions will not be considered “combinational”.

It shall be possible to pre-empt a CS call which is part of a combinational service.

It shall be possible to add a precedence call to an IMS session.