Research Of Session Initiation Protocol Model Based On Specific Event Notification

The Session Initiation Protocol (SIP) is an application-layer control (signaling) protocol distributed by IETF for creating, modifying, and terminating sessions with one or more participants. These sessions include Internet telephone calls, multimedia conferences, and multimedia distribution.SIP invitations used to create sessions carry sessions description that allow participants to agree on a set of compatible media types. SIP makes use of elements called proxy servers to help route requests to the user's current location, authenticate and authorize users for services, implement provider call-routing policies. SIP also provides a registration function that allows users to upload their current locations for user by proxy servers. SIP runs on top of several different transport protocols.The purpose of this thesis is to explore the designing idea, content, and realization mechanism of SIP, analyzes the request and response message, entity and message body of SIP in detail. On the basis of exploring, analyze the simple SIP network model and present the way of improving this system: SIP Model based on Specific Event Notification. This model offers SIP Specific Event Notification to transmit DTMF, and uses SUBSCRIBE and NOTIFY to realize the control to IP phone. So this model not only realizes the features in the old model but also maintains the good communication with PSTN. This model combines PSTN PBX with IP PBX and realizes it in LAN of enterprises. At last, the thesis offers the way to realize a part of this model, and analyzes the performance of this new model, lists the advantages and disadvantages, and points out the direction of improvement.