[Asterisk-Dev] HylaFAX and spandsp

[Lee Howard]

(Please forgive me for not replying sooner and for not replying 
in-thread on this.  I was not subscribed to the Asterisk-Dev list and 
didn't notice this thread until just recently in an on-line archive.)

Steve Underwood wrote:

> Some people are happy with the spandsp soft-FAX the way it
> is. Some people want to see its FAX modem work with HylaFAX.
> In an attempt to please the entire universe, a class 1 FAX
> modem interface for spandsp is now on the way. I just made
> my first FAX call between a spandsp without HylaFAX, and a
> spandsp with HylaFAX.

Congradulations.  Could you elaborate a bit on how you did it with 
HylaFAX (the approach)?

> Now I have a question. What should this look like as a
> complete application? The current applications which allow
> use of mu soft-FAX, rxfax and txfax, are transient
> applications. What form should a soft-FAX modem for HylaFAX
> take? Should I follow the same transient application format,
> launching a copy of HylaFAX's faxgetty as needed? If so, what
> about the FAX sending side. Should I be building a persistent
> application with a persistent copy of HylaFAX attached? HylaFAX
> experts, please tell me what will suit HylaFAX best, as I am no
> HylaFAX expert.

I think that it would work "best" to have an Asterisk "T.38" channel 
driver that can talk to OpenH323's t38modem.  That would make your work 
useful for other packages other than just HylaFAX.  In the future 
HylaFAX development could create a T.38 driver so as to not use 
t38modem, thus eliminating the pitfalls and shortcomings of the 
AT-command interface.

If you don't want to approach it that way, then I can only see it 
working "seamlessly" by creating a pseudo-modem with the appropriate 
T.31 AT-command interface with which HylaFAX faxgetty and faxsend could 
interact.

If you don't want to approach it that way, then you'd need to write a 
new HylaFAX driver to communicate with your Asterisk channel.

I would be happy to go into detail if you ask specific questions.

Thanks.

Lee.