[Asterisk-Users] one way / irratic voice over iax and g729

[Ben Dinnerville]

Hi All,

We are experiencing a a problem when running calls over IAX with g.729. 
The call flow is as follows:

Sip handset -(SIP)> Asterisk1 -(IAX)> Asterisk2 -(SIP)> Carrier

The first Asterisk system is running 1.2 and the second is running 1.0. 
When using g726 from the handset all the way thru to Asterisk2(then 729 
for the carrier leg) calls go thru fine, but when using g729, there is 
one way voice whereby the B party cannot hear the A party, however the A 
party can hear the B party  fine. Sometimes there is no audio for the B 
party, other times the B party can hear the A party but it is very 
broken up and stuttery, with only parts of the words coming through. The 
calls also work fine when using g711 from the A party.

Asterisk2 is running a couple of TDM04B's so there is a physical timing 
device on that side and Asterisk1 is running ztdummy on a 2.6 kernel - 
so there is timing on that side also (??)

Have done a fair bit of searching on this one, and as it only happens 
with g729 (both systems have the licensed codecs installed) it is a bit 
of a head scratcher - has anyone else experiencved this? Or does anyone 
have any feedback?

Cheers,

Ben