[Asterisk-Users] Fax via email

[Steve Underwood]

Kevin P. Fleming wrote:

> Steve Underwood wrote:
>
>> spandsp doesn't try to reimplement all of HylaFAX. It reimplements 
>> only one piece - the T.4/T.30 code. I have a half implemented 
>> "spandsp as class 1 fax modem" which I put aside. People are using 
>> spandsp happily for things like fax to e-mail. Introducing HylaFAX 
>> would really slow things down. That said, I'd really like to complete 
>> the class 1 modem interface, and make HylaFAX an option for people.
>
>
> Well, I was thinking of HylaFAX running on another box, with some type 
> of IAX2 "virtual FAX modem" client running on the same machine, using 
> IAX2 to communicate to Asterisk. That would remove the CPU usage from 
> the Asterisk box and put it where it belongs.

If you want to FAX over IP you need to be *very* careful if you want it 
to be reliable. You cannot use anything other than A-law or u-law as the 
codec. However, even using those, any data slips will kill the FAX 
operation. If the two boxes are on the same LAN it tends to work OK.

> I'm curious how you think "HylaFAX would really slow things down", if 
> you mean something other that CPU usage? I'd see adding HylaFAX to the 
> mix as adding well-tested and reliable ECM, MR, MMR and other protocol 
> support on top of the virtual modem you've already implemented, as 
> well as supporting alternative FAX origination methods (email, print, 
> etc.).

I mean CPU loading. HylaFAX only does 1D coding (unless that changed 
very recently) and the ECM is brand new. The features you list may be a 
lot less well tested than you think. :-) Also, only a tiny fraction of 
FAX machines can even support ECM.

Regards,
Steve