[Asterisk-Users] asterisk codec negotiation problem

[bladerunner]

hello list,

i searched for nearly a week for a solution to this problem, as there is:

analog fax machine -» grandstream ata -» asterisk -» sip trunk from provider 
-» provider gateway to pstn -» analog/isdn fax machine on pstn

everything worked out fine until my provider decided to implement t38 into the 
gateway. now when i send/receive a fax message the gateway tries to connect 
with t38 and waits for a "media capability unknown" to receive if the device 
on the sip trunk is incapable of talking t38, in order to fall back to the 
old g711 behaviour.

but asterisk does not answer with "media capability unknown" (sorry, did 
forget the sip message number), he answers with his own codec capabilities, 
and this is ignored by the gateway. so he tries to send with t38 anyway, and 
that of course fails.

any thougts on that one?

kind regards,

michael