Patent ID: 7672661

Claim:
A management server, comprising: a determination unit configured to determine a communication network to which a receiving mobile terminal, which is a mobile terminal acting as a receiver of a call and which is connectable to a plurality of communication networks by one telephone number, is connecting; and a notification unit configured to issue a first notice to the receiving mobile terminal based on a result of determination by the determination unit, wherein the first notice is configured to indicate the communication network to which the receiving mobile terminal connects, when the communication network to which the receiving mobile terminal connects is changed while the call is in progress, the determination unit is configured to determine that a subject to be charged for the call is changed from an originating mobile terminal, which is a mobile terminal acting as an originator of the call, to the receiving mobile terminal, and the notification unit is configured to issue a second notice to the receiving mobile terminal when the subject to be charged is changed to the receiving mobile terminal, the second notice indicating that the subject to be charged for the call is changed from the originating mobile terminal to the receiving mobile terminal.