A multi-signaling protocol architecture for voice over IP terminal

This work describes a novel multi-signaling protocol architecture of a VoIP end point in an IP packet network. The endpoint is a single channel IP phone or gateway, but can handle H.323, SIP or MGCP calls simultaneously to/from different end points. The other endpoints could be using any of the signaling protocols. The endpoint is registered to a media gateway controller, SIP server and a H.323 gatekeeper, possibly with the same number. The details of the design including the state machines of the different call control modules are described. The advantage of such architecture is reduced delay in call setup between two endpoints that otherwise use different signaling protocols. The architecture has been implemented and verified on one of the company´s IP phone chip, which has an ARM7 and a DSF core. An example of a simple handling of a second call from a different protocol endpoint, when the first call is in progress, has also been given.