Patent ID: 8335211

Claim:
A communication system comprising: a router and a control server, said router accommodating a telephone terminal, an internet protocol (IP) terminal, and an application server, wherein said router comprises: a first interface to said IP terminal; a second interface to said telephone terminal; a third interface to said application server; and a fourth interface that accommodates a voice communication line and a data communication line connected to said control server, said control server comprises: a name management table in which a mapping among a domain name of said application server, a data communication line IP address of said router, and a session initiation protocol-uniform resource identifier (SIP-URI) is stored; a domain name system (DNS) processing unit configured to access the name management table and to perform processing for establishing a correspondence among the domain name of said application server, the data communication line IP address of said router, and the SIP-URI; a status management table in which a mapping among a session status information on said router, the data communication line IP address, and the SIP-URI is stored; a SIP processing unit configured to access the status management table and to perform processing for controlling a session with said router and for establishing a correspondence among session status information on said router, the data communication line IP address, and the SIP-URI; wherein, said DNS processing unit is configured to search the name management table for a SIP-URI corresponding to destination information included in a name resolution request transmitted from said IP terminal, and wherein said SIP processing unit is configured to search the status management table for the session status information corresponding to the SIP-URI found by the DNS processing unit from the name management table, wherein the SIP processing unit is configured to connect a session with said router via a voice communication line when the session status information that has been searched for in the status management table includes information indicating “disconnect”, and to transmit a connection request, which requests to connect to the data communication line to said router.