Figure 7.6.1.2.3.5.1-1 describes how IMS consultative ECT is performed when ICS UE A is playing the role of transfer initiator using I1 interface. The ICS UE A has a held call with UE B and an ongoing call with UE C before transfer.
Step 1.
The ICS UE A initiates transfer of UE B to UE C by sending a transfer message to SCC AS using I1 interface.
Step 2.
Completion of referring UE B to UE C as specified in
TS 24.173 and releasing the session between the ICS UE A and UE C.
Step 3.
The SCC AS sends the transfer complete message to ICS UE A via I1 interface.
Step 4.
The ICS UE A releases the calls between it and UE B.
Figure 7.6.1.2.3.5.1-2 describes how IMS consultative ECT is performed when ICS UE is playing the role of transfer recipient using I1 interface. The UE A has a held call with UE C and also has a held call with ICS UE B before transfer.
Step 1.
UE A initiates transfer of ICS UE B to UE C by sending a REFER request as specified in
TS 24.173.
Step 2.
The S-CSCF sends the REFER to the SCC AS as it was inserted at session establishment.
Step 3.
The S-CSCF sends a transfer message to the ICS UE B via I1 interface.
Step 4.
The ICS UE B initiates a call initiation message to SCC AS via I1 interface.
Step 5.
Completion of referring the ICS UE B to UE C as specified in
TS 24.173 and releasing the session between the UE A and UE C.
Step 6.
The ICS UE B provides an indication that the communication transfer is complete to SCC AS via I1 interface.
Step 7.
The SCC AS sends a NOTIFY message to the S-CSCF.
Step 8.
The NOTIFY is sent to UE A.
Step 9.
The UE A initiates session release with ICS UE B and release the session.
Figure 7.6.1.2.3.5.1-3 describes how IMS consultative ECT is performed when ICS UE is playing the role of transfer target using I1 interface. The UE A has a held call with UE C and also has a held call with ICS UE B before transfer.
Step 1.
UE A initiates transfer of UE B to ICS UE C by sending a REFER request as specified in
TS 24.173.
Step 2.
An INVITE is sent by UE B upon reception of the REFER request as specified in
TS 24.173, and received at the S-CSCF of the ICS UE C.
Step 3.
The S-CSCF executes terminating initial filter criteria and forwards the INVITE message to the SCC AS.
Step 4.
The SCC AS sends an incoming call request to the ICS UE C over I1 reference point. The incoming call request indicates that a new session between UE C and UE B is to replace the current session between UE C and UE A.
Step 5.
Completion of referring UE B to the ICS UE C as specified in
TS 24.173 and releasing the session between UE A and the ICS UE C.
Step 6.
UE A initiates session release with UE B and releases the session.
Figure 7.6.1.2.3.5.2-1 describes how IMS Blind ECT is performed when ICS UE A is playing the role of transfer initiator using I1 interface. The ICS UE A has a held call with UE B before transfer.
Step 1.
The ICS UE A initiates transfer of UE B to UE C by sending a transfer message to SCC AS using the I1 interface.
Step 2.
Completion of referring UE B to UE C as specified in
TS 24.173 and releasing the session between the ICS UE A and UE B.
Step 3.
The SCC AS sends the transfer complete message to ICS UE A via the I1 interface.
Figure 7.6.1.2.3.5.2-2 describes how IMS blind ECT is performed when ICS UE A is playing the role of transfer recipient using the I1 interface. The UE A has a held call with ICS UE B before transfer.
Step 1.
UE A initiates transfer of ICS UE B to UE C by sending a REFER request as specified in
TS 24.173.
Step 2.
The S-CSCF sends the REFER to the SCC AS as it was inserted at session establishment.
Step 3.
The S-CSCF sends a transfer message to the ICS UE B via I1 interface.
Step 4.
Step 5.
The ICS UE B initiates session establishment towards UE C by initiating a call initiation message to SCC AS via I1 interface.
Step 6.
Completion of session establishment between the ICS UE B and UE C as specified in
clause 7.6.1.2.2.5.2, steps 15-22.
Step 7.
The ICS UE B provides indication that the communication transfer is complete to SCC AS via I1 interface.
Step 8.
The SCC AS sends a NOTIFY message to the S-CSCF.
Step 9.
The NOTIFY is sent to UE A.