Abstract: A gatekeeper supporting a handoff and handoff method in an IP telephony system is disclosed. The gatekeeper is configured to perform third-party pause and rerouting (3PPR) signaling and to support the handoff using 3PPR signaling, so that a mobile terminal does not need to have a H.450.2 stack function. In addition, for a fast connect call, the H.245 control channel is induced and the 3PPR signaling, which is made through the H.245 control channel, is performed for every call including the fast connect call. Thus the handoff using the 3PPR signaling can be provided to every call. Moreover, the H.245 control channel for the fast connect call is set on the basis of the tunneling during a telephony, so that the fast connection can be maintained as it is and, thus, the fast handoff signaling can be provided.

Abstract: A method for supporting a global IP telephony system in an NAT-based private network is disclosed. The disclosed method includes: establishing a special channel for exchanging information for address translation with a NAT router and identifying the type of a dynamic NAT mode of the NAT router using the special channel. A private address contained in a signaling message forwarded to a public IP terminal is transmitted to the NAT router using the special channel, according to the type of the dynamic NAT mode. A public address is dynamically assigned for the private address by the NAT router and used to replace the private address in a regenerated signaling message. The regenerated signaling message is then transmitted to the public IP terminal. The public address assigned by the NAT router is released when a call is terminated. Since the information required in each H.

Abstract: A system, device and method are provided for processing a call between a private exchange network and a mobile communication network in which a wireless trunk connection system or the like is used. A call is processed through the wireless trunk connection system in the private exchange network without passing through a public communication network when it is intended to establish a communication between an extension subscriber to the private exchange network and a subscriber to the mobile communication network. The wireless trunk connection system can have connections to a first mobile station for transmitting the destination telephone number dialed by the extension subscriber of the private exchange network to the mobile communication station through the first mobile station when the extension subscriber to the private exchange network requests communication services to the mobile communication network.

Abstract: A gatekeeper supporting a handoff and handoff method in an IP telephony system is disclosed. The gatekeeper is configured to perform third-party pause and rerouting (3PPR) signaling and to support the handoff using 3PPR signaling, so that a mobile terminal does not need to have a H.450.2 stack function. In addition, for a fast connect call, the H.245 control channel is induced and the 3PPR signaling, which is made through the H.245 control channel, is performed for every call including the fast connect call. Thus the handoff using the 3PPR signaling can be provided to every call. Moreover, the H.245 control channel for the fast connect call is set on the basis of the tunneling during a telephony, so that the fast connection can be maintained as it is and, thus, the fast handoff signaling can be provided.

Abstract: A method for supporting a global IP telephony system in an NAT-based private network is disclosed. The disclosed method includes: establishing a special channel for exchanging information for address translation with a NAT router and identifying the type of a dynamic NAT mode of the NAT router using the special channel. A private address contained in a signaling message forwarded to a public IP terminal is transmitted to the NAT router using the special channel, according to the type of the dynamic NAT mode. A public address is dynamically assigned for the private address by the NAT router and used to replace the private address in a regenerated signaling message. The regenerated signaling message is then transmitted to the public IP terminal. The public address assigned by the NAT router is released when a call is terminated. Since the information required in each H.