说明：  RAT是一个网络音频工具，它允许用户通过因特网加入一个音频会议。这种会议可以仅有两个参与者，也可以是一个有多个参与者的多播组。对于点对点的模式而言，RAT并没有什么别出心裁之处，然而对于多播的情况，RAT就有很多优势了。RAT遵循IETF标准，使用UDP/IP之上的RTP作为其传输协议，同时也符合RTP有关音频和视频会议最小控制的有关规定
(RAT is a network audio tool, which allows users to join an audio conference through the Internet. Such meetings can consist of only two participants, or a multicast group with multiple participants. For point to point mode, RAT does not have any originality. However, for multicast, RAT has many advantages. RAT follows the IETF standard, uses RTP on UDP/IP as its transport protocol, and conforms to RTP's relevant provisions on minimum control of audio and video conferencing.)