Implementation Of Communication Device Integrating VoIP Technology With Telecommunications Technology Based On Linux Platform

Nowadays, mobile communication service has developed to an indispensable part of people’s life. However, it still has some shortcomings, such as limited bandwidth resources, poor indoor signal quality, high call cost etc. Fortunately, the VoIP technology can perfectly solve the above problems of telecommunication technology. To allow users to enjoy the advantages of VoIP technology and the reliability of telecommunication technologies, a device which integrates VoIP technology with telecommunication technology is presented in this thesis.In this paper, we survey and analysis the SIP protocol in depth, and introduce SIP protocol entities, the structure and the composition of SIP message and SIP extensions. Then the features and functions of PJSIP protocol stack and BlueZ bluetooth protocol stack are introduced. This communication device is based on PJSIP protocol stack and BlueZ Bluetooth protocol stack and is designed and achived under the Linux operating system. The device contains telecommunication network interface module, IP network interface module, VoIP module, Control module and user interface module. The telecommunication network is the interface to make the device access to telecommunication network; IP module provides the internet interface; VoIP module is responsible for referring to buddies’online information, and send or receive calls through VoIP network; Control module controls other modules to establish, maintain and release calls through this communication device; user module provides the interface which enable the interaction between the communication device and users。The following is the communication process of the communication device:in the initial stage of the session, the call is carried out through the VoIP network if both the calling and called are online and during the call, the device will periodically detect the drop rate and the calling part should control to handover the call to telecommunication network if the drop rate exceeds a threshold. If either the calling or the called or both of them are offline in the initial stage, the call should be carried out through telecommunication network and during the call the control module will periodically detect whether the called part is online and the calling part should control to handover the call to VoIP network once both the calling and called are detected online. The device has the following features:based on open and standardized VoIP technology, low cost, the phone cost is saved, the user habit is not changed, the problem of poor indoor signal quality of mobile communication is solved, saving the wireless bandwidth resource, and so on.