| 摘要 |
PURPOSE: A GK(GateKeeper) for supporting handoffs in an IP telephony system and a handoff method thereby are provided to efficiently support handoffs using 3rd P and R(Third party initiated Pause and Rerouting) signaling through an H.245 control channel for all the calls including fast connect calls. CONSTITUTION: The third MT(Mobile Terminal), allocated a COA(Care Of Address) from a ZONE2 FA, requests registration to an FGK(Foreign GK)(S161,S162). The FGK transmits a binding update request message to inform an HGK(Home GK) that the first MT has become the third MT(S163). The HGK transmits a binding update confirm message to the third MT through the FGK in order to admit registration(S164,S165). Then the HGK makes an FT(Fixed H.323 Terminal) in a pause state(S166-S168), sends a setup message to the third MT, and makes a Q.931 channel with the third MT(S169). Receiving the setup message, the third MT executes an ARQ/ACF(Admission ReQuest/Admission ConFirm) process with the FGK(S170,S171). At this moment, the FGK selects a direct signaling mode. Due to the FGK's selection, the third MT opens the Q.931 channel directly with the HGK without the FGK(S172,S173). Accordingly, the HGK connects the FT to the third MT and supports the handoff(S174-S176). |
