Peers is a very minimalistic SIP User-Agent. It s a softphone, written in java, and it has been tested on linux and windows. It allows a user to call from one PC to another on a local area network, using SIP/SDP/RTP with Ulaw encoding for voice.

pjsip工程，是一个开源的SIP协议库，他实现了SIP、SDP、RTP、STUN、TURN和ICE-pjsip project is an open source SIP protocol library, he realized the SIP, SDP, RTP, STUN, TURN and ICE