Patent ID: 8768321

Claim:
A communication system that enables a group talk, comprising: a call control server; and a message transmission server, wherein the call control server comprises: a call request receiver configured to receive a first call request for calling out group talk members; a call request generator configured to generate a second call request for calling out the group talk members corresponding to the first call request, on the basis of the received first call request; and a call request transmitter configured to transmit call request receiving information indicating that the first call request is received, prior to transmitting the generated second call request to the group talk members, wherein the message transmission server comprises: an information receiver configured to receive the call request receiving information transmitted from the call control server; and a start-up message transmitter configured to transmit a start-up message, which includes member identification information of the group talk, wherein a login processing is executed to the call control server on the basis of the start-up message, and the second call request is generated on the basis of the executed login processing.