To provide a gateway device for performing SIP session control by proxy without acquiring any special information from a terminal on which any SIP session control function is not mounted.
A communication system includes: a first network; a data server for individually storing the management information of a terminal; and a second network for performing call control. In the communication system, a gateway device connecting the first network to the second network includes: an address solving part (26) for, when detecting a DNS query issued by a terminal connected to itself, confirming whether or not management information corresponding to the identification information of communication terminal at the other party is stored, and for, when it is not stored, acquiring management information corresponding to the identification information from the data server; and an SIP session control part (27) for, when detecting the connection request, executing call control processing in the second network by using the management information corresponding to the identification information included in the connection request.
FURUYA SHINJI
TANABE MOTOFUMI
SOMA SHINGO
YOKOYA TETSUYA
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