| 摘要 |
PURPOSE: An Internet phone system and its operation method are provided to ensure a smooth Internet phone service with a gateway positioned outside an NAT(Network Address Translation) network by allocating an external IP address and a UDP port number to a gateway of an NAT network having a private IP address. CONSTITUTION: An originating gateway(11) transmits a ARQ(Admission Request) message to a gate keeper(5)(S100) and receives an ACF(Admission Confirmation) message(5)(S101). The originating gateway(11) detects an IP address and a UDP port number of a destination gateway(6), and transmits a setup message including a voice channel proposal message(S102,S103). The destination gateway(6) call setup request message to the gate keeper(5)(S104) and receives a call setup confirmation message(S105). The destination gateway(6) selects a certain channel, displays its IP address and UDP port number in a voice channel accept message, and transmits an alert message(S106,S107,S106a,S107a). The originating gateway(11) and the destination gateway(6) perform an Internet phone call(S108). When the destination gateway(6) desires to terminate the call(11), it transmits a release complete message to the originating gateway(11)(S109,S110) and a disengage request(DRQ) message to the gate keeper(5)(S111), and then receives a DCF(Disengage Confirmation) message and terminates the Internet phone call(S112). The originating gateway(11) transmits a call stop request message to the gate keeper(5)(S113), receives a call stop confirmation message, and terminates the Internet phone call(S114).
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