Patent ID: 8521224

Claim:
A communication system comprising: a mobile management apparatus that controls communication between mobile terminals; and an internal line managing apparatus that controls communication, via the mobile management apparatus, between mobile terminals that are used as internal phones, wherein the internal line managing apparatus includes a user information storing unit that stores therein, in association with an internal phone number of a mobile terminal, call status information that indicates whether the mobile terminal is in a call connection, and providing-subject information that indicates which one of the internal line managing apparatus and the mobile management apparatus provides a supplementary service, a call determining unit that determines, when an internal line call request is input with respect to a destination mobile terminal from a source mobile terminal, whether the destination mobile terminal is in a call connection in accordance with the call status information stored in the user information storing unit in association with the internal phone number of the destination mobile terminal, an internal-line-party service providing unit that provides the supplementary service associated with the destination mobile terminal that is in the call connection, a forwarding unit that forwards an internal line call request input to the mobile management apparatus, and a providing-subject determining unit that determines, when an internal line call request is received, a providing subject of the supplementary service associated with the destination mobile terminal in accordance with the providing-subject information stored in the user information storing unit in association with the internal phone number of the destination mobile terminal and that outputs the internal line call request to the call determining unit when the providing subject of the supplementary service is the internal line managing apparatus, and that outputs the internal line call request to the forwarding unit when the providing subject of the supplementary service is the mobile management apparatus, and the mobile management apparatus includes a mobile-party service providing unit that provides, when the internal line call request is received from the forwarding unit, a supplementary service that is provided when a call request is received with respect to the destination mobile terminal that is in a call using the mobile phone number.