Patent ID: 7039059

Claim:
A VoIP (Voice over IP network) gateway device connected between a digital exchange for performing intra- and inter-office tandem exchange of a 64-kbps PCM (Pulse Code Modulation) digital voice signal and an IP (Internet Protocol) transit trunk, comprising: identification pattern insertion means for inserting an identification pattern of a predetermined bit pattern in a receiving signal from the IP transit trunk, and sending out the signal to the digital exchange; identification pattern detection means for detecting an identification pattern from the receiving signal from the digital exchange; first frame conversion means for converting an RTP (Real-time Transport Protocol) packet obtained from the IP transit trunk into a digital voice signal in a pass through frame format having a bit rate of 64 kbps, an output of said first frame conversion means passed to said exchange when said identification pattern detection means detects an identification pattern; and second frame conversion means for converting a digital voice signal in the pass through frame format received from the digital exchange into an RTP packet, an output of said second frame conversion means passed to said transit trunk when said identification pattern detection means detects said identification pattern.