Transmission method for dual-tone multi-frequency (DTMF) stream in voice over Internet protocol (VOIP) network and gateway device

The invention discloses a transmission method for a dual-tone multi-frequency (DTMF) stream in a voice over Internet protocol (VOIP) network, and particularly relates to a solution for the high loss rate of the DTMF stream which is transmitted on the Internet through compressed voices in the application of a conventional voice gateway. In the method, a fixed telephone line is taken as a transmission path, and a transmission process comprises a transmitting terminal processing step and a receiving terminal processing step. The DTMF stream transmitted on the Internet is classified and extracted, and a transmission control protocol (TCP) channel only for a DTMF class is established, so that a receiving terminal can compare a DTMF sequence and a real-time transport protocol (RTP) sequence andfinally recover an optimal DTMF stream for output. The invention also discloses a DTMF-stream-transmission-method gateway device. The DTMF sequence in a TCP stream is compared with an audio sequence of an RTP stream, and the method comprises a checking process and an error code recovery process, so that data transmission reliability is greatly improved.