[Freeswitch-users] Simple IAX2 setup - help with converting from asterisk to freeswitch

[Matthew Law]

Thanks for the comprehensive reply.  I have switched to using plain SIP
and the experiments continue...

Matt

On Sat, February 6, 2010 11:11 pm, Derek Smithies wrote:
> Sigh.
>   the web pages are wrong.
>
> I have implemented the earlier version of IAX2 inside the opal library. At
> one stage, I could make a voip call using IAX2 to digiums test server.
>
> The standard IAX2 codebase did not (at one stage) support silence
> suppression. With silence suppression, the bandwidth usage is halved.
> Using efficient packing of audio makes a few percent of difference. Doing
> silence suppression makes 50% of difference to bandwidth.
>
> IAX2 is more efficient? Most(>90%) of the cpu work when doing voip is in
> the codec. By using a non standard approach (iax2 audio packets) for
> carrying audio, you will have a minimal gain in effiency (or cpu usage).
> Remember that iax2 uses the same codecs as in H.323/SIP. Oh - you are
> right, g711 is a codec, and has trivial cpu cost. However, with g711 any
> bandwidth you save on the header is negligible compared to the size of the
> encoded audio block.
>
> Secure? Security protocols (HIP, ZRTP, etc) take years of careful
> development to get something that works well. I do not recall seeing
> evidence of years of development going into IAX2 security. Either the
> author of the security in IAX2 is a pure genius, able to do in
> days/weeks what other do in years,,,, or the iax2 security is
> average (at best).
>
> Yes, all the iax2 packets go to the same port. This has huge advantages
> for getting through firewalls, and setting up firewalls to accept incoming
> calls. It does (slightly) increase the complexity inside the iax2 code.
>
> ===================================
>
> if you want iax2 inside freeswitch, my suggestion is that the opal library
> needs to have the iax2 code there brought up to spec, and then used (in
> the same way as the H.323 component of the opal library).