With the development of the network technology and communication technology , now the network technology and communication technology that originally was a parallel line has finally mixtured together, and has risen a new disciplines - network communication technology. Network communications technology in recent years as a rapid development brand of the scientific branch, is very meaningful to be studied. Particularly, today's companies, state-run institutions are all develop the network, regardless of what industry and what career both can not remain outside of the network, so the LAN-based network for real-time voice communication is extremely important. This paper is based on the LAN on the text of the duplex voice instant messaging systems, mainly for internal LAN communications enterprises and institutions is to build a basic platform for enterprises employees to work and communicate more easily, and also for staff to work more effective. This is the core of papers on Socket (socket) communications technology that achieve the two sides’ communication with server and client communication