Design and implementation of a VoIP phone using a microprocessor board

Transmission of voice over an IP network (VoIP) is very important as it lays theground for data and voice network convergence, which allows tremendous cost savingsfor both enterprises and carriers. Session Initiation Protocol (SIP), developed by theInternet Engineering Task Force (IETF), is the emerging VoIP signaling protocol that isused to setup, terminate and modify associations between Internet end systems,including conferences and point-to-point calls. With the emergence of VoIP using SIP,many SIP phones have emerged on the market. These phones both come in software,called a SoftPhone, and hardware varieties. A hardware SIP phone is implemented usinga cheap microprocessor board with a network interface such as Ethernet or 802.11. Suchphones must have a full-fledged SIP stack with a small footprint requiring minimalsystem resources.In this thesis, our goal is to design and implement a hardware SIP phone using amicroprocessor board. The main motivation is to obtain a standards-compliant, smallfootprint SIP stack implementation that would require minimal resources when run in anembedded system. We have implemented a layered SIP stack and deployed it on theUbicom microprocessor board. To test the implemented SIP stack, a SIP proxy server, aSIP presence server and a SIP registrar have also been implemented. Finally, we haveintegrated a commercial SIP SoftPhone, X-Lite, into the system, and successfully testedthe compatibility of our SIP stack implementation with X-Lite.