Patent ID: 9078234
Filing Date: 2015-07-07
Classification: H04W

Abstract:
1. A method of operating a mobile station, comprising: registering the mobile station with a first base station of a plurality of base stations provided within at least one radio network, wherein only some of the plurality of base stations support a Voice over Internet Protocol (VoIP) service; activating Idle mode Signalling Reduction (ISR) functionality at the mobile station following the step of registering the mobile station with the first base station, such that the mobile station is configured to send a Routing Area Update Request message or a Tracking Area Update Request message to any one of the plurality of base stations only under a set of predetermined conditions, the set of predetermined conditions being independent of the functionality of any of the plurality of base stations to support VoIP; after activating the ISR functionality at the mobile station, deciding to move communications service for the mobile station to a second base station of the plurality of base stations; after activating the ISR functionality at the mobile station, determining at the mobile station that one of the first base station and the second base station has functionality to support VoIP and the other does not; and sending a Routing Area Update Request message or Tracking Area Update Request message from the mobile station to the second base station in response to said determination regarding functionality to support VoIP.