Failure and Cancellation

For cases of failure and/or cancellation, the ATCF behaves in accordance with TS 23.216 [3], Section 8:

• In the case of session failure before the MSC server initiates session transfer, the standard failover procedures (as defined in TS 23.401 [2])apply and no further action is required by the UE.
• In the case of session failure after the UE receives the handover command, the UE attempts to return to the Universal Mobile Telecommunications System (UTRAN) or evolved Universal Mobile Telecommunications System (eUTRAN). The UE initiates signaling to transfer the session back, which the ATCF handles if the ATCF recognizes the session transfer.
• In the case when handover is cancelled, the UE—having received the handover cancellation message—begins the re-establishment procedure as though it needed to transfer the session to the eUTRAN/UTRAN. If he ATCF identifies this as a transfer session, it handles the session transfer back to the eUTRAN/UTRAN.