Patent ID: 8526447

Claim:
A device for fax interworking, the device comprising: an H.323 interface; a Session Initiation Protocol (SIP) interface; and a processor operable to: establish a voice call between an H.323 endpoint and a SIP endpoint; transmit a fax mode request message to the H.323 endpoint through the H.323 interface in response to receiving a fax invite message from the SIP endpoint through the SIP interface; close any open logical channels for voice between the H.323 endpoint; open a logical channel for fax between the H.323 endpoint by exchanging messages with the H.323 endpoint, the messages comprising an Internet Protocol (IP) address and a Real-Time Transport Protocol Control Protocol (RTCP) port; establish a fax call between the H.323 endpoint and the SIP endpoint after opening the logical channel for fax; and end the fax call by switching back to the voice call, wherein switching back to the voice call comprises: transmitting a voice mode request message to the H.323 endpoint through the H.323 interface in response to receiving a voice invite message from the SIP endpoint through the SIP interface; closing the logical channel for fax between the H.323 endpoint; and opening a logical channel for voice between the H.323 endpoint.