[asterisk-users] Bad Voice Quality - IAX2 redirect

[hugolivude]

Asterisk 1.2.7
RedHat 9.0

Hi,
I've run into some voice degradation problems with IAX2:

I frequently have calls come in on a DiD provided by an ITSP.  I often
have to redirect these calls back out to the PSTN (i.e. to a cell
phone).  When this happens,  I don't want my server in the media path,
I want to hand it off to my ITSP instead and let them handle both ends
of the call.  I've been very careful to avoid using t or T in my dial
commands.

I couldn't get this to work with SIP (I'm behind a NAT BTW).  No
matter how I tried, the media continued to pass through my server, so
I switched from SIP to IAX2.

I've had much better success redirecting calls back to the PSTN using
IAX2.  I can see the handshakes in the CLI and once the redirected
call had been established, I can phyically disconnect my * server from
the Ethernet and the call is unaffected.

Unfortunately I'm getting complaints about call quality (I use ulaw
the whole way).

I don't think the problem can possibly be on my server or its
configuration given that the call is completly handed off as described
above.  Surely this must be the ITSP's problem, but perhaps I'm
missing something?  Any suggestions are welcome!

Thanks,
H