Patent ID: 8453230

Claim:
A communicating apparatus comprising: at least one hardware processor connected to at least one memory; a communicating unit configured to perform communication that uses a SIP server on a network; a detecting unit configured to detect unauthorized communication from the communication performed by said communicating unit; a changing unit configured to change a port number of a receiving port of said communicating unit when said detecting unit detects the unauthorized communication; a determining unit configured to determine whether or not the unauthorized communication detected by said detecting unit has passed through the SIP server; and a controlling unit configured to request the SIP server to delete the port number of the receiving port that has not been changed yet by said changing unit if said determining unit determines that the unauthorized communication has passed through the SIP server and to re-register on the SIP server a port number of a receiving port that has been changed by said changing unit if said determining unit determines that the unauthorized communication has bypassed the SIP server; wherein the detecting unit, the changing unit, the determining unit, and the controlling unit are implemented, at least in part, by the at least one hardware processor and the at least one memory.