[asterisk-users] Fax with Asterisk and T38Modem

[Thorolf Godawa]

Hi,

I'm fighting with HylaFAX, Asterisk and T38Modem since some time, to get
fax2mail and mail2fax working, my SIP-provider only supports T38 and
thus using G711 with IAXModem is not an option.


I have got running mail2fax with HylaFAX+ 5.5.0, Asterisk 1.4.20 and
T38Modem 2.0.0 successfull, but I'm not able to upgrade to anything
newer than Asterisk 1.4.24.

I was able to break down this problem to some changes in the chan_sip.c,
where a "improved support for T38 on initial INVITE" has been
implemented (see:
https://reviewboard.asterisk.org/r/208/diff/#index_header).

I'm not sure what the problem is, but it seems that the T38 handshake
does not work correct any more.

Goal is, to get running this with the latest Asterisk, right now 1.8.4.3,

Is there s.b. who can give me a hint how to solve the problem?


For fax2mail I use Asterisk 1.8.4.3, but it is not working too, after a
fax call, the connection with T38Modem is established, HylaFAX reports
"ANSWER: FAX CONNECTION DEVICE '/dev/ttyT380'", but a fax is never received.

In the tcpdump I see the correct handshaking between Asterisk and
T38Modem, but finaly T38Modem switches to "recvonly" and Asterisk
answers with "SIP/2.0 488 Not acceptable here" and the call ends shortly
after that.


Probably there is a problem in T38Modem, so I filed a bug at sourceforge
for that:

https://sourceforge.net/tracker/?func=detail&aid=3337581&group_id=152230&atid=783657

But may be, somebody has a solution for this too.


Thanks a lot,
-- 

Chau y hasta luego,

Thorolf