When I use G711 between asterisk and the ipbx, it works. But I want t38 between asterisk and the ipbx. When the IPBX receives a fax in g711 and issues an (re)INVITE for T38, I get an error 488 NOT ACCEPTABLE HERE replied by asterisk 11.25.
For testing purpose, I’ve setup:
(telco sip) <—g711–> asterisk 11.25 <----t38—> asterisk 11.21
same issue
and I get the error on the asterisk 11.25:
[Jan 3 22:43:20] ERROR[21508][C-00000003]: res_fax.c:1072 fax_session_new: Could not locate a FAX technology module with capabilities (V21)
[Jan 3 22:43:20] ERROR[21508][C-00000003]: res_fax.c:2569 fax_gateway_new: Can’t create V21 session on chan SIP/telcotrunk-00000006 for T.38 gateway session
[Jan 3 22:43:20] ERROR[21508][C-00000003]: res_fax.c:4108 acf_faxopt_write: Error attaching T.38 gateway to channel SIP/telcotrunk-00000006.
From the CLI on the Asterisk 11.25 machine execute a
asterisk -rx “core show applications like fax”
and post your results - from the line above, I think you don’t have SPANDSP Fax compiled/loaded.
This is what it should look like:
[root@asterisk ~]# asterisk -rx “core show applications like fax”
-= Matching Asterisk Applications =-
ReceiveFAX: Receive a FAX and save as a TIFF/F file.
SendFAX: Sends a specified TIFF/F file as a FAX.
-= 2 Applications Matching =-
I think that is the problem for what you are trying to do - Gateway a T.38 session - the FAQ is here: http://my.digium.com/en/docs/FAX/fax_faq/ but from everything I have read, FFA is more of a termination or origination - not a Gateway solution.
Perhaps a Digium person can weigh in here, but I think to do what you want, you will need the SpanDSP FAXing to make this work - getting it compiled into Asterisk is not at all hard.
Asterisk can’t translate from g711 to t.38, and from t.38 to g.711. If You want to do it, You’ll have to use gateway functionality in dialplan or in sip.conf.