asterisk users - Jan 2010 - Asterisk status "488 Not acceptable here" on receiving fax

Hello,

I have been trying to setup asterisk 1.6.1.1 to receive fax. Whenever
a SIP peer (zoiper soft phones) tries to send a fax message asterisk
responds by sending a "488 Not acceptable here" and the sending fails.
I tried changing a few sip settings like canreinvite and codec
preferences, but it did not help. The same sip peer is able to make
normal calls.

The same settings works on on asterisk 1.6.2.0 and I am able to
receive fax successfully in asterisk. I would like to get this working
in 1.6.1.1 as It is not possible for me to upgrade asterisk on my
production servers.

Can someone please help.

Thanks,
Deepesh