Patent ID: 7002989

Claim:
A method of interworking via a state machine for use in interworking between an H.323 based network and a session initiation protocol (SIP) based network, the method comprising: receiving, at an interworking server that includes a data processor for call processing and a memory for storing said state machine, a set-up request from an H.323 endpoint, transmitting a corresponding invite message to an addressed SIP endpoint, receiving a ringing response message from the SIP endpoint, transmitting a corresponding alert message to the H.323 endpoint, receiving an OK message from the SIP endpoint, transmitting a connect message to the H.323 endpoint, negotiating said connect message utilizing an H.245 protocol, transmitting an ACK message to the SIP endpoint, communicating between the H.323 endpoint and the SIP endpoint utilizing realtime transport protocol (RTP), establishing a state machine table in said memory, including an idle state, wherein for a state of said state machine, a message associated with said state is categorized as one of: (a) a triggering message for triggering a predetermined action, (b) a non-triggering message, and (c) an unexpected message in said state; and for the idle state, defining: (a) registration messages as triggering an addition of registration information, (b) a Q.931 message as non-triggering, and (c) an H.245 message as an error message.