ABSTRACT
The voice communication services can be realized as follows: convert voice signals to digital signals, compress coding and package the signals in groups, then turn the analog signals into IP telegrams with Internet as transmitting medium
1 INTRODUCTION
In recent years, with the continuous development of Internet technology, IP-based real-time voice trans-mission technology has gradually become mature and VoIP (Voice Over Internet Protocol) telephone has been more and more widely used (Runsheng & Xiaorui 2004). The expansion of mobile communication services and the popularity of smart phones provide a strong market thrust for the application and promotion of soft-switching system which belongs to VoIP and achieves voice communication function through software. Given the fact that the Android system plays an absolute leading role in the mobile terminal market, this article uses Android NDK (Native Development Kit) integrated with SIPDroid (SIP open source protocol stack) as development environment after an in-depth study of the VoIP-related technology and Android platform, designs and realizes the VoIP communication system based on SIP protocol of Android terminal. The main achievements are as follows:
1. The paper analyses and studies VoIP technology, SIP protocol and Android technology, focusing on Android NDK development framework and SIPDoird architecture. We comprehensively understand and master the technological theories used by the system, which lays a solid theoretical foundation for the design and implementation of the system.
