PS to CS SRVCC (Single Active Call)

The SC UE includes a capability indicator (included by the lower layers) during UE NAS registration (see 3GPP TS 24.501 [98], for indicating support for SRVCC from NG-RAN to UTRAN), attach and updating procedures (see 3GPP TS 24.301 [52] and 3GPP TS 24.008 [8], for indicating support for SRVCC from E-UTRAN or UTRAN to UTRAN or GERAN).

PS to CS SRVCC with MSC server assisted mid-call feature

The SC UE includes the "g.3gpp.mid-call" media feature tag in the Contact header of the initial SIP INVITE request.

Upon receiving a SIP INVITE request including the g.3gpp.mid-call feature-capability indicator in the Feature-Caps header field, the SC UE includes the "g.3gpp.mid-call media feature" tag in the Contact header field of the SIP 2xx response.

PS to CS SRVCC for calls in alerting phase

The SC UE includes the "g.3gpp.srvcc-alerting" media feature tag in the Contact header of the initial SIP INVITE request.

Upon receiving a SIP INVITE request including the "g.3gpp.srvcc-alerting" feature-capability indicator in the Feature-Caps header field, the SC UE includes the "g.3gpp.srvcc-alerting" media feature tag in the Contact header field of the SIP1xx and SIP 2xx responses.

PS to CS SRVCC for originating calls in pre-alerting phase

The SC UE includes the "g.3gpp.ps2cs-srvcc-orig-pre-alerting" media feature tag in the Contact header of the initial SIP INVITE request.

CS to PS SRVCC (Single Active Call)

The SC UE includes a capability indicator (included by the lower layers) during UE attach and updating procedures (see 3GPP TS 24.008 [8]) in order to inform the BSS of CS to PS SRVCC support from GERAN.

The SC UE includes the "g.3gpp.cs2ps-srvcc" media feature tag in the Contact header field of the SIP REGISTER request.

CS to PS SRVCC with MSC server assisted mid-call feature

The SC UE includes an Accept header in the SIP INVITE request due to STI-rSR containing the application/vnd.3gpp.mid-call+xml MIME type for support of the additional session transfer.

CS to PS SRVCC for calls in the alerting phase

The SC UE includes the "g.3gpp.cs2ps-srvcc-alerting" media feature tag in the Contact header field of the SIP REGISTER request.

The SC UE includes an Accept header in the SIP INVITE request due to STI-rSR containing the application/vnd.3gpp.state-and-event-info+xml for support of the alerting session transfer.

PS to CS dual radio access transfer (single active call)

For support of access transfer for an SC UE without ICS capabilities, the SC UE uses a dynamic STN for the access transfer if it supports the use of dynamic STN and receives the dynamic STN from the SCC AS. Otherwise, the SC UE uses a static STN.

The SC UE indicates support for the dynamic STN by including the "g.3gpp.dynamic-stn" media feature tag in the Contact header of the initial SIP INVITE request and in the Contact header of SIP 1xx and SIP 2xx responses to the SIP INVITE request.

Upon receiving the dynamic STN in the "g.3gpp.dynamic-stn" feature-capability indicator in the Feature-Caps header field of a SIP INVITE request, SIP 1xx or SIP 2xx response, and the SC supports the use of the dynamic STN, the SC UE replaces the static STN with the dynamic STN.

PS to CS dual radio access transfer with MSC server assisted mid-call feature

The SC UE includes the "g.3gpp.mid-call" media feature tag in the Contact header of the initial SIP INVITE request.

Upon receiving a SIP INVITE request including the "g.3gpp.mid-call" feature-capability indicator in the Feature-Caps header field, the SC UE includes the "g.3gpp.mid-call media" feature tag in the Contact header field of the SIP 2xx response.

PS to CS dual radio access transfer for calls in alerting phase

The SC UE includes the "g.3gpp.drvcc-alerting" media feature tag in the Contact header of the initial SIP INVITE request.

Upon receiving a SIP INVITE request including the "g.3gpp.drvcc-alerting" feature-capability indicator in the Feature-Caps header field, the SC UE includes the "g.3gpp.drvcc-alerting media" feature tag in the Contact header field of all SIP 18x responses to the SIP INVITE request.

PS to CS dual radio access transfer for originating calls in pre-alerting phase

The SC UE includes the "g.3gpp.ps2cs-drvcc-orig-pre-alerting" media feature tag in the Contact header field of the initial SIP INVITE request.

CS to PS dual radio access transfer (single active call)

The SC UE uses a dynamic STI for the access transfer if it is configured to use ICS capabilities. Otherwise, the SC UE uses a static STI.

CS to PS dual radio access transfer with MSC server assisted mid-call feature

The SC UE includes an Accept header in the SIP INVITE request for static STI containing the application/vnd.3gpp.mid-call+xml MIME type, for support of the additional session transfer.

CS to PS dual radio access transfer for calls in the alerting phase

The SC UE (not using ICS capabilities) includes the "g.3gpp.cs2ps-drvcc-alerting" media feature tag in the Contact header field of the SIP INVITE request for static STI.

CS to PS dual radio access transfer for originating calls in the pre-alerting phase

The SC UE (not using ICS capabilities) includes the "g.3gpp.cs2ps-drvcc-orig-pre-alerting" media feature tag in the Contact header field of the SIP INVITE request for static STI.

PS to PS acess transfer

When the "PS to PS STI" is configured, the SC UE includes the "g.3gpp.pstops-sti" media feature tag in the Contact header field of a SIP REGISTER request.

PS to CS dual radio access transfer for emergency session

The SC UE includes the "g.3gpp.dynamic-e-stn-drvcc" media feature tag in the Contact

NOTE 1: ICS capabilities can be used by the SC UE for support of access transfer. Configuration for ICS is specified in 3GPP TS 24.292 [4].