| Since the first specification for SIP (Session Initiation Protocol)-RFC2543 was delivered in 1999, it has been developing rapidly. Nowadays, SIP is being used as the signaling protocol in fields of 3G mobile telecommunication and NGN. Furthermore, SIP is widely deployed in traditional VoIP applications. Because of high flexibility, SIP has already become the focus of research and development in fields of telecommunication and network. In this background, the second specification for SIP- RFC3261 and the implementation of UA are studied in this dissertation.Firstly, the generation and development of VoIP, softswitch and NGN are introduced. Then the generation, functions and advantages of SIP are introduced and several open- source SIP stacks are discussed in this dissertation.Secondly, the architecture, call flows, syntax, components and entities of SIP are analyzed on the basis of studying RFC3261. SDP and RTP/RTCP-the two types of protocol which related to SIP are introduced. Based on those works mentioned above, a new implementation of SIP stack with layered software architecture is proposed. At the same time, the architecture, designing and processing flows of each layer are detailed in the dissertation with especially emphasis on their key technologies. The parsing of its message, transaction processing, dialog managemen and those data structures with importence are detailed respectively.Finally, a softphone running on the Windows platform which made use of the stack is developed to show the implementation of UA. |
PDF Full Text Request