| 摘要 |
<p>Methods for providing improvement in Voice-over-IP communication systems, and hardware for implementing the methods, are disclosed. A first aspect provides a method of improving on the efficiency of RTP used to transport VoIP voice calls by reducing the overhead of second and subsequent calls on a link to almost zero using trunking. A second aspect uses bandwidth awareness to compress RTP payload data captured from the network. This involves capturing G.711 encoded RTP data directly from the network ( as opposed to at source ) and transcoding that data in such a way as to take account of the available bandwidth on an outbound link. A third aspect uses dynamic and transparent packet fragmentation and reassembly based on RTP interval to reduce VoIP latency and jitter. A fourth aspect uses dynamic re-writing of SIP messages to provides automatic fail-over and load balancing of SIP servers. This involves capturing SIP call set-up messages and re-writing and duplicating them to direct them to multiple servers. The response is monitored to determine which server responds most quickly and allowing only that reply back to the source device. A fifth aspect provides dynamic sizing of trunk payload packets. Given that the above scheme has been set up on a link, it is trivial for the receiving trunk device to determine if the received packets are too big or small, and to signal the transmitter to adjust its payload size accordingly.</p> |
