asterisk users - Jun 2012 - Asterisk 10 T.38 and 012 in Israel

Hi all

I'm trying to get asterisk 10 spandsp get faxes from 012 in israel (they use
broadsoft switches)  using T.38 more reliable and would like to know if anyone
knows of any changes I could make or ask them to make.
As it stands now I get much more reliability receiving faxes with iaxmodem with
no T.38 which is funny than when having asterisk receive using T.38 and if I try
using gateway mode to iaxmodem then its even worse.

I'm trying to test how much reliability will I loose when moving from a pri
which is excellent but expensive to voip and T. 38.  How much tradeoff

Thanks in advance,
Israel