Patent ID: 8600375

Claim:
Method for optimizing the reduction of mobility signaling after an Inter-Radio Access Technology (IRAT) change for a User Equipment (UE) roaming between a source area covered by a source telecommunication core network (CN) having a source Radio Access Technology (RAT) and a target area covered by a target core telecommunication network having a target RAT, wherein a signaling reduction function is activated by the source telecommunication core network, and wherein deactivation triggering events of the signaling reduction function generates a need for registration update at next IRAT change occurred, the method being characterized by the following steps: a—storing in the UE a parameter the value of which indicates whether or not the deactivation triggering events of the signaling reduction function only correspond to a UE context modification in the source RAT, and, after the IRAT change, b—checking the event generating said IRAT change, and, c—checking the value of said parameter, d—cancelling the need for registration update or validating the need for registration update depending on the event generating said IRAT change and on the value of the stored parameter.