Implementing SIP and H.323 signalling as Web services

Nowadays, existing voice-over-IP (VoIP) clients are signalling protocol dependant. This means that they can only support one signalling protocol. One disadvantage of these VoIP clients is that they are rich clients, and the other is that the problem of interoperability between two clients supporting different signalling protocols must be solved by a signalling protocol translator. We propose a VoIP Web services architecture, taking advantage of the Web services technology to solve the above problems. This work explores the design and implementation of a VoIP Web services system architecture. We first propose a VoIP Web service architecture, and then we focus mainly on designing the signalling protocol Web services, and illustrate the call procedures between the simple client and the normal H.323/SIP client under this architecture. We also present the experience in implementing the prototype for the H.323/SIP Web services, and finally give some considerations about the implementation.