[Asterisk-Users] Fax over IP doesn't works

[Steve Underwood]

Darren Sessions wrote:

> We used spandsp on the voip side. Our inbound vendor sets the call up 
> G711 and spandsp answers. It's a bit slow as it seems to only 
> negotiate v29 terbo, but it works.
>
> Finding the correct version of libtiff was a pain. One sub version 
> off, and it wouldn't work. Wasn't so much that it was a hard to get it 
> to work, just a lot of tweaking to get it to work. Tedious.

It only supports V.29 (there is no terbo) ofor patent reasons. I have 
nearly finished V.17, but I'm unclear if the patent on its trellis 
coding has run out.

libtiff and timing slips are the two big issues, and there is little I 
can do. The recent libtiff security patches should fix most of the 
libtiff issues, I hope. Why so many people have timing problems has 
still to be resolved. Some have been misconfigured E1s/T1s, but there 
seem to be plenty of others. There is nothing I can do about that within 
spandsp.

spandsp on the VoIP side will always be a little flaky, I'm afraid. 
There is little I can do about that either. Building spandsp was 
actually a step towards T.38. That is why I have not been too interested 
in a HylaFAX interface (although one is in progress).

Regards,
Steve