Patent ID: 8190149

Claim:
In a communication system comprising a first portable system which includes a first GGSN and a first SGSN, and a second portable system which includes a second GGSN and a second SGSN, where if a mobile station roams from a first radio coverage area supported by said first portable system into a second radio coverage area supported by said second portable system then said second SGSN implements a method comprising the steps of: initiating a PDP context deactivation process which causes the first GGSN to teardown a PDP context associated with the mobile station and also causes the mobile station to deactivate a PDP context associated with the PDP context that was torn down by the first GGSN; participating in a PDP context activation process where the second GGSN is selected to serve the mobile station and a new PDP context is established with the mobile station and the second GGSN; and triggering a start of said initiating step after a predetermined amount of time has passed since a timer was started upon completion of a routing area update process which was started when the mobile station roamed into the second radio coverage area supported by said second portable system, wherein the timer is canceled and the start of said initiating step is triggered upon an occurrence of a predefined condition.