Design And Implementation Of SIP Client System Based On Android

Nowadays, computer and network techniques have been rapidly developed and universally employed. The demands for multimedia communication of network became more.The most popular VoIP signaling protocol is SIP protocol(Session Initialization Protocol).The SIP protocol is proposed by the Internet Engineering Task Force working group in1999.It is a text-coding based IP application layer signaling control protocol, it is mainly used to create, modify and release the sessions of one or more participants.In recent years,SIP has more widely used because of the advantages of simplicity, flexibility, opening and extension. The Android platform, which is of powerful features, good interface, a wide range of business supports, became one of the most popular operating system of smart mobile phone.The thesis studies SIP protocol and related extended protocols of SUBSCRIBE, MESSAGE in detailed.Meanwhile, the in-depth study for the RFC3261-based open source protocol stack-the OSIP and its extended EXOSIP protocol stack has been performed. Combining with Android platform and based on NDK development framework, a SIP client system is designed and implemented.The designed SIP client system includes four modules:the user client module, the voice processing module, transmission module and the main control module.The user client module implements the SIP-related functions, which includes SIP-registration, basic call function, status subscription, instant messaging, call holding, call transferring and other functions;Voice processing module mainly includes the functions of voice acquisition, encoding, transmission, receiving, decoding, playback, etc;Transmission module processes messages and voice data transmission;main control module includes user interface and local calling interface to achieve their specific functions.The system integrates E-mail function and contacts funciton except realizes the basic functions of SIP client, which enables E-mail to be sent and friends to be added and managed in the SIP client directly.The test for SIP client system designed in this thesis shows that the stability of the various functions,which indicates the success of design. The compatibility is also achieved when compared with other SIP client systems.