[Asterisk-Users] What is IAX Trunking?

[Andrew Yager]

On 04/07/2004, at 11:24 PM, Deon Rodden wrote:

> Sorry, I've been on voip-info.org but I still can't get a clear 
> definition
> of what IAX trunking is. It says you need the timing from a zaptel 
> device
> (or ztdummy or zaprtc) to make it work, but nothing specific about 
> what it
> is or what it does. Maybe I'm looking in the wrong place.

The best place to look is:

http://www.voip-info.org/wiki-Asterisk+bandwidth+iax2

But in a nutshell - IAX trunking allows multiple voice streams to share 
a single "trunk" to another server, reducing overhead created by IP 
packets.

"This trunking eliminates the IP overhead found in individual VoIP IP 
streams by pipelining RTP data from multiple calls into single (larger) 
packets, thus removing the redundancy of IP overhead for each RTP 
stream and more closely allowing bandwidth scaling as a function of 
codec usage instead of a function of (codec usage + IP overhead.) Of 
course, this mode can only be used if all the calls are between two 
specific Asterisk servers, but this is frequently the case with 
toll-avoidance situations or between two branch offices where there is 
an Asterisk server at each location. "

Andrew