[asterisk-biz] fax on demand

[Lee Howard]

Mitul Limbani wrote:

> I guess you are aware of this bounty : 
> http://www.voip-info.org/wiki/view/Asterisk+T.38+Bounty


The bounty has grown some over time, but it's still far, far too little 
for anyone to get it done motivated only by the bounty.

To meet with the requirements on that bounty the developer would need to 
not only code up some software DSPs (V.21, V.27ter, V.29 and ideally 
V.17), but also code up a T.30 processor as well as T.38 and also then 
somehow extend IAX2 protocol to support T.38 (because the bounty asks 
for T.38 over IAX2).  It's just an insane amount of work to expect it to 
get done by motivation of a bounty like this.  And then... to expect 
that person to disclaim it to Digium - well, in my opinion the bounty as 
presented is insultingly small for that kind of thing.  Hardware modem 
manufacturers pay insane amounts of money to DSP vendors... it's not 
exactly for nothing, either.

That said, Steve Underwood made a tremendous effort on getting T.38 
pass-through support into Asterisk... which is why you see it now 
appearing in 1.4.  Yet, if you were to take a look at the bug report 
that he initiated to get that done (and I don't have it bookmarked any 
more - the entertainment wore off) you'll see how depressingly difficult 
it was for him to even get just that done (so difficult that he gave up 
on it).  And that's just passthrough (on SIP)... not meeting the full 
lofty goals of that bounty request.  (Passthrough is really only helpful 
if your VoIP provider also supports T.38 - and if your VoIP provider 
*does* support T.38 you can know for certain that they're not doing the 
PSTN gateway with Asterisk.)

OpenPBX has had that T.38 SIP pass-through for a while now, and I 
believe that the T.38 gateway support is now near production-worthy as 
well.  OpenPBX can do that because it doesn't have to deal with the 
dual-license limbo that Asterisk does - so everything getting into 
spandsp (including full T.38 support) - is entirely license compatible.  
But that doesn't necessarily mean that OpenPBX will fulfill every users' 
ambitions, either.

Personally I'd like to see every PBX and fax machine in the world 
support T.38.  However, having watched Asterisk users clamour for full 
T.38 support for years now... and having seen where the development 
trends have gone... I don't think that it's going to happen soon enough 
to consider.

Lee.