[asterisk-dev] Fax with Asterisk and T38Modem

[Thorolf Godawa]

Hi Steve,

thanks a lot for your anwers.

> I am not sure why you don't use ulaw between Asteirsk and Hylafax.
It's not what I want to use, it's what t38modem and Asterisk are using
and in Europe alaw is used.

> I use IAXmodem and hylafax, so I am no expert on T38Modem, but same concept.
Well, it was quite easy to get running HylaFAX with Asterisk 1.8 and
IAXmodem. IAXmodem uses G.711 alaw and it turned out, that this is not
reliable at all and our provider only supports T38 so we will have to go
there.

> Also please note that you need to set canreinvite = no for t38modem to
> work. Additionally if the incoming calls arrive in G.729 you need to
> have a G.729 codec installed on your asterisk in order for T38modem to
> do a T.38 Re-Invite back."
canreinvite is set to "no", I will check if this does change anything.

Using G.729 for fax is even worse than using G.711, but the faxes only
come with G.711 or T38.

> I always use a second NIC and a crossover cable unless the customer
> doesn't need it or want it
I do not think that you need a second NIC with crossover cable, it is
running if you bind everything to the external IP-address of the
NIC/server. It will not work with localhost or an alias-IP.

> Let T38Modem handle the T38 between the carrier and you.  If everything
> is running on the same box, you should have no issues as long as the
> server is powerful enough.
This is the goal, but actually it makes no difference if Asterisk is
running on the same box or not. Up to 1.4.24 it works, beginning with
1.4.25 (I tried up to 1.4.42rc and 1.8.4.4) the initial handshake fails.

> If you post more details, like what you were upgrading, logs, debugging
> info and conf files, will you get your answers much faster.
Right now I try to fix the second t38modem-problem for fax2mail and
because it may be a t38modem-problem, I put all the log in the tracker
for that.

> Please post if you make any progress or find a solution so people don't
> have to think for themselves anymore.
For sure I will do so.

-- 

Chau y hasta luego,

Thorolf