Re: [hylafax-users] faxing over sip

[Robert Moskowitz <rgm@xxxxxxxxxxxxxxx>]

Lee, you have done a great job on all of this....

Lee Howard wrote:
> Robert Moskowitz wrote:
>
> > Interestingly, IAXModem is enough like V.34 (It does have Steve's 
> > spandsp code built-in) to work over most Internet connections (I am 
> > told it does breakdown when the Net gets congested and RED kicks in 
> > on the routers).
>
> I don't really understand the correlation between IAXmodem and V.34, 
I will ASSuME that I did not read through the code right. After all, I 
never did program in C. I did program in B, but had pretty muched 
dropped out of the programming world long ago...
> but yes, I have done a number of things with IAXmodem to try to 
> compensate for VoIP issues. However, I suspect that the vast majority 
> of the compensations are due to things done in HylaFAX/HylaFAX+, 
> namely a tolerant Class 1 ECM protocol.
And THAT is a major accomplishment!
> > Also once IAXmodem incorporates this version of spanDSP, it should 
> > work as well with T.38.
>
>
> Well, I have considered making IAXmodem use spandsp's T.38 features 
> rather than the DSP... but I haven't settled on doing that. If 
> t38modem works then I don't have any reason to do that. 
I was going to make a comment about T38modem, but based on comments 
further down, I will hold off.
> Furthermore, I don't have any immediate motivation to develop T.38 
> projects right now (I've no customers that depend on it).
And this is part of the mindset that after T.38 has been around for a 
number of years, we are still talking about it. But I know all about 
getting bread on the table.
> > Another piece of the puzzle is T38Modem for Hylafax. A number of 
> > people use that. But us Trixbox people cannot as it requires kernel 
> > patches to Centos :(
>
> t38modem 1.0.0 (in the OPAL project) supports both SIP and UNIX98 
> ptys. So... if that code can ever make it out of CVS/SVN then there's 
> no patching of kernels required.
This is VERY encouraging. But without an RPM for RHEL/Centos, I am not 
going to see it soon. Unless the Trixbox team take on the building of 
the RPM (as they have for spandsp).
> > FAX is holding back large-scale movement to VoIP over classic 
> > switched circuits. Classic switch circuits are going away and except 
> > for 'lifeline' will start costing more. More people are going with 
> > GSM for their only phone, and GSM CANNOT support T.30; no how/no way.
> >
> > T.38 will be the key piece that pulls fax over to the Internet along 
> > with everything else. 
>
> I disagree with this to some extent. I do not doubt that fax is 
> holding some people back from changing fully to VoIP. I do not 
> believe, however, that it is holding back a large-scale movement. I 
> have had enough experience with businesses and VoIP over the last few 
> years to realize that to many of them the quality of their phone calls 
> is too important, too valuable to concern themselves over the price 
> difference. The occassional audible jitter, the disconnections, etc... 
> they aren't worth the price savings to them.
I am dyslexic and have 'word selection challenges', sorry, 'large-scale 
movement' is too open to interpretation.

Market analyses that I have access to continue to show fax as a major 
requirement for small/home businesses. Efax has not been a successful 
replacement ( e.g. scanner-email interfaces are just broken for 
transmissions). Hospital usage of fax is tied into HIPAA (I work on the 
security side of it, and fax is the fallback if you cannot prove your 
security, and thus you just fallback). Invoicing and other usage is only 
slowly moving to EDI over IP (the AS3 standard that last year Wal*Mart 
finally standardized on). So afx hangs around and will for a good 10 
years. But these are not the volume users. They will continue to use 
PSTN (and miss that a large part of their content goes through efax 
gateways!).

We need an IP fax solution for the masses.
> It's really not a technical problem to solve, either. VoIP cannot 
> reliably replace the PSTN in all cases. It's not a clear "better-than" 
> kind of thing here. I think that over time you're more likely to see a 
> hybridization of VoIP and PSTN instead of a clear migration.
Back when Windows 3.0 came out (I was on the beta and the beta of OS/2 
2.0), I told my manager that Microsoft did IT a great service. Users 
were no longer demanding perfect, non-failing systems like they had 
gotten use to with IMS and CICS. The 3-finger solute was accepted behaviour.

Likewise, cellular has turned around user acceptance of call quality. 
Look at devices like the Dock-N-Talk. There is no reason for ANY PSTN 
circuit for the vast majority of users. And in some countries (Finland?) 
this is long established.

There is a lot of jocking around in the Telco/Cable/Cellular world. The 
IP costs versus traditional comm costs are driving this (plus user 
demand for 'IP'). Small Asterisk/Hylafax boxes with enum and other 
services, are going to be a 'subversive technology'.


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