Demand for rich media services such as internet access , video on demand , digital television and voice over ip grows more clamorous every day 对丰富的媒体服务的需求，如因特网接入、视频点播、数字电视和ip电话，日日高涨。
In chapter , the echo cancellation technique in ip gateway is studied . after that , we discuss the implement of echo canceller based on dsp 最后研究ip电话网关上的回声消除技术，给出基于dsp的回声消除器的软硬件实现。
The ip phone info server is a kind of application server to provide an information service for the ip phone in the softswitch network 本项目开发的ipphoneinfoserver就是为软交换环境中的ip电话提供信息服务的一种应用服务器。
The ip phone codec carry out the tasks of collecting and playing - back of speech signal , and asynchronous communication with pc ' s serial port , etc 该ip电话编解码器实现了语音信号的采集、回放、与计算机的串口异步通信等功能。
In ip phone system , the application requires to use abundant system resources of servers , which often causes a choke point in the server 摘要ip电话系统中，因多用户并发访问，服务器的资源处于瓶颈状态，严重影响了系统的性能。
Based on the study of theories , the author had developed a voip billing and management system . the result product is in use today 在理论研究的基础上，作者结合企业实际需求开发了ip电话计费和综合管理系统，并投入实际运行。
In this paper , we use jain technology and nist sip stack develop a ip - telphone system which include a sip - ua , a proxy and a location server 可以和符合该协议的商业sip软件互通。这些都对ip电话的实际运营的技术问题提供了解决方案。
Take the ip services carried out by china unicom in harbin for example , we can analyze and calculate the economic benefits of the ip phone services 并就黑龙江省联通在哈尔滨地区开放ip电话业务分析计算了开放ip电话带来的经济效益。
