HANDOVER OF EMERGENCY CALLS FROM A CIRCUIT SWITCHED TO A PACKET SWITCHED ACCESS NETWORK

摘要

A method is provided of performing a handover with SRVCC to a target PS access network of an emergency call to a PSAP from a UE accessing a CS access network. The method includes sending a handover request from the CS access network towards an I MS network to transfer the emergency call. A CS to PS emergency handover command is sent to the UE, including an emergency STN identifying an access transfer control function. The UE sends a SIP INVITE to establish an emergency IMS session over the PS access network. The SIP INVITE includes the emergency STN so that the INVITE is routed to the access transfer control function. The emergency call sent over the CS access network with the emergency I MS session are correlated and the emergency call is switched to the emergency IMS session over the PS access network to complete the handover.