[Asterisk-Users] Advantage of IAX2 to SIP?

[Rich Adamson]

> Some - few - providers are using IAX2 as a protocol. Most are using SIP. 
> I know that there are advantages of IAX2 regarding multiple connections. 
> But beside this I'm asking myself (and you all) why I should prefer IAX2 
> when my SIP connection is working.
> 
> Are there differences in the performance?

Generic answer: most of the sip providers require g711 which consumes about
80kb/s of bandwidth, and a fair number of those are non-asterisk based
systems that don't have iax2 support. Most/all iax2 providers are asterisk
based and typically support other codecs besides g711. Iax2 with gsm
consumes roughly 30kb/s, which on a typical dsl broadband connection, is
preferred by most asterisk users.

There are several other technical advantages for iax2, one of which is its
ability to carry multiple calls within a single packet reducing the IP
overhead on the net. (Bigger bang for the broadband buck.)

The downside of iax2 is that its not yet a standard (rfc or otherwise)
and even though its gpl'ed, few non-asterisk systems have bothered to
implement it as yet.