本书介绍了IP多媒体通信技术，包括语音编码、SIP、H.323等等。-This book introduced the IP multimedia communication technology including voice coding,SIP and H.323.

FreeSWITCH是以C撰写而成的开放源码电话应用软件，可以连接SIP H.323、IAX2、LDAP、Zeroconf、XMPP / Jingle，Google Talk等现有技术，架构出开放源码PBX系统或开放源码的VoIP交换平台。-FreeSWITCH based on open source telephony application software written in C by, can to connect SIP H.323, IAX2, LDAP, Zeroconf, X