A General Method of New Feature Service Development on VOCAL

VOCAL (Vovida open communication application library) is an open-source code program that provides a SIP-based (session initiation protocol) VoIP (voice over Internet protocol) communication. So far, a lot of projects lay emphasis on the research of customized redevelopment based on VOCAL, but the technical documentation is not for sharing. Feature server is an important part of VOCAL. The Feature services of the feature servers, which is also referred to as Internet phone value-added services. "Outgoing multicast" has the ability to make a group call efficiently and successfully. This thesis firstly analyze the principles of feature services on VOCAL with combination of techniques in SIP, CPL (call processing language), XML (Extensible Markup Language), and etc. and then efforts on how to develop and design "fork calling", in order to generalize a method of developing new future service. This will have significant effects on the VOCAL-based industrial development, which is also concord with the protocol of VOCAL open-source-code and to popularize the Internet phone