[asterisk-users] Codec swap (reinvite)

[Julian J. M.]

Hi,

I've finally given up on trying to fax over my Digium TDM400 card.
I've found that fax over VoIP is quite more reliable (at least I can
receive the faxes).

My ITSP supports G729 and alaw/ulaw. As I won't be receiving faxes
everyday (just ocasionally), i pretend on using g729, unless a fax is
detected.

Is there any way to force asterisk to make a reinvite, and swap the
codec on the fly? Something like this would be great:

exten => fax,1,CodecChange(ulaw)
exten => fax,2,rxfax(blablabla)

Thanks,
   Julián J. M.