Patent ID: 9596342
Date: 2017-03-14
CPC Classifications: H04M,H04W

Claim:
1. A mobile station capable of providing a voice communication service via an IP multimedia subsystem and configured to execute a transition from a first radio access system with no circuit-switched domain to a second radio access system with a circuit-switched domain, comprising: a voice communication control circuit configured to execute continuation processing of the voice communication service in the second radio access system if the mobile station makes a transition of a connection destination from the first radio access system to the second radio access system during an alert period when the other party in the voice communication service is being alerted; and a ringing tone control circuit configured to output a NW-provided ringing tone or a local ringing tone during the alert period, the NW-provided ringing tone being transmitted from a network via the first radio access system or the second radio access system during the alert period, the local ringing tone being based on data stored in the mobile station, wherein the ringing tone control circuit outputs the NW-provided ringing tone based on that the NW-provided ringing tone is being outputted before the continuation processing of the voice communication service, without outputting the local ringing tone, after a transition to the second radio access system if the voice communication control unit circuit executes the continuation processing of the voice communication service during a period when the NW-provided ringing tone is being outputted.