Patent ID: 8559986

Claim:
A method for changing an Access Service Network (ASN) of a Mobile Station (MS) in a communication system, the method comprising: when an MS that operates in an idle mode moves from a first ASN to a second ASN, transmitting, at the MS, a ranging request message to a base station of the second ASN in order to update a location; transmitting, at the base station, a location update request message to an ASN-GateWay (GW) of the second ASN according to the ranging request message; transmitting, at the ASN-GW, a relocation notify message comprising type information for location update and an Optimized Relocation (OR) type comprising Optimized Combined Relocation (OCR) cause information to the first ASN when the location update request message is received; and transmitting, at the first ASN, a relocation notify response message comprising paging information to the ASN-GW according to the relocation notify message, wherein the OCR cause information denotes Location Update (LU) trigger information.