共查询到16条相似文献,搜索用时 234 毫秒
1.
2.
3.
4.
5.
6.
7.
8.
本文首先分析了对H.323域间通信进行单独研究的必要性。然后介绍了ITU-T对该问题研究的最新进展。在介绍了域间模型、地址模版等基本概念和域间通信使用的消息等内容后,给出了H.323域间呼叫路由的详细工作过程。文章还对域间呼叫路由方式进行了举例分析。最后给出了需要进一步研究的问题。 相似文献
9.
10.
11.
介绍了IP电话网守的概念,功能和呼叫信令的两种方式,讨论了呼叫转移在IP电话中的一种实现方法,在局域网、单网守的条件下得到了实现。 相似文献
12.
13.
文章分析了将UM业务融入IP电话系统中实现的优越性 ,确定了通过IP电话系统网守实现对UM服务器的管理机制 ,研究了该UM服务器的主要技术、系统结构、媒体信息的收发方式和安全策略等关键问题 ,完成了基于IP电话系统的UM业务的实现方案并成功开发了这一方案的UM原型系统。 相似文献
14.
15.
This paper describes a speech predictive encoding communications (SPEC) system that is designed to accommodate the traffic ofN PCM telephone trunks in the capacity ofN/2 PCM telephone channels. The system exploits the statistics of multichannel voice communication in a manner significantly different from the technique employed in the well-known time-assignment speech interpolation (TASI) system. Specifically, the SPEC system operates at the transmitter by removing redundant speech samples during talk bursts as well as during silence intervals. The receiver remembers the most recent sample transmitted through each channel. As long as a new sample is not transmitted, the receiver simply repeats the sample value stored in its memory. Each sample from each incoming trunk is examined every 125 μs to determine which samples must be transmitted and which are redundant. Because the SPEC system operates at this high speed and predicts redundant or missing samples at the receiver, it does not produce the speech clipping effects typical of TASI-like systems. Any voice-quality degradation due to increased call load and/or speech activity is manifested as an increase in noise power. The subjective result is a graceful degradation that is virtually imperceptible to the listener. 相似文献
16.