Patent ID: 7778243

Claim:
A method for DTMF (Dual Tone Multi-Frequency) transfer between different address systems in a communication system containing a first network including an SIP server using SIP (Session Initiation Protocol) and an SIP terminal connected to the SIP server through a network, a second network including an SIP server using SIP and an SIP terminal connected to the SIP server through a network, and an SIP converter for connecting the first network and second network, the method comprising: while a session is established between the first-network SIP terminal and the second-network SIP terminal, the SIP converter determining whether the SIP terminal of the other of the networks supports coded DTMF information when the SIP converter detects the coded DTMF information from one of the networks; and after producing a voice-data format DTMF information based on a type of DTMF and a reproduction time information of the coded DTMF information, the produced voice-data format DTMF is stored into a payload on RTP (Transport Protocol for Real-Time Applications) and transferred to the other of the SIP terminals, and then data without voice with respect to more than a predetermined time, is stored into a payload on RTP and transferred to the other of the SIP terminals, if the SIP terminal of the other of the networks does not support the coded DTMF information; and the coded DTMF information is transferred to the SIP terminal of the other of the networks if the SIP terminal of the other of the networks support the coded DTMF information.