[asterisk-users] alarm POTS lines

[Lee Howard]

Jeff LaCoursiere wrote:
> I don't think I have a prayer of hacking iaxmodem to do what is 
> needed to emulate a modem though :)

I can't pretend to know what an alarm system needs out of a modem, but 
as far as iaxmodem acquiring data-modem capabilities that part is 
already developing.  IAXmodem inherits its DSP capabilities from 
spandsp, and you can see on the spandsp that certain modem types are 
already available in the newer spandsp snapshots.  That doesn't mean 
that you can expect iaxmodem or spandsp to work for you anytime soon 
out-of-the box, but know that eventually you'll see this happen.

> Between the dockstar and the ATA 
> (which I am already providing for dialtone anyway) it is around a $40 cost 
> solution for me, and the customer gets to drop the POTS line, which is 
> around a $30/month savings for them.  I'd probably just eat the added cost 
> to get the customer, and could even charge some modest fee for the "alarm 
> connection" that would still in the end save them money.

....

> Look at fax, for example.  Wouldn't we love to tell our 
> customers to dump their old fax machines for scanners and email?  Some people 
> just won't until the thing catches fire or otherwise dies.
>   

There are many reasons besides ignorance that faxes (and thus fax 
machines) are still around.  For one, there is a serious technological 
work-flow hurdle involved with the scan-to-email approach replacing fax 
completely because, for one, it's not like you can do that for every one 
of your would-be fax recipients.  Consequently trying to replace faxing 
with a scan-to-email approach ultimately means that someone still has to 
do some faxing.  As it's typically easier to send a fax than to 
scan/attach/email, work-flow productivity will actually drop by forcing 
the abandonment of fax machines (i.e. by utilizing a mail-to-fax service 
for intended recipients where a direct e-mail will not work).

(I'm convinced that fax machines are with us for the long-haul.  Now, 
whether or not futuristic fax machines operate directly with a POTS line 
or with IP connectivity seems clear that it will eventually become a 
hybridization, but I truly believe that those who engineer that future 
technology will necessarily have to divorce the IP-side of the systems 
away from the whole modulation/demodulation over audio channels bit.  On 
an IP network it simply makes no sense to take a data stream, and 
modulate it to audio only to demodulate it back to a data stream again 
because the IP network makes the modulation/demodulation superfluous 
where it was necessary on the PSTN.  So this running of T.38 FoIP over 
SIP VoIP is consequently a passing phase; it's not a solid-enough 
solution to replace traditional faxing.)

> So is there anyone out there with the DSP skills to do the "iaxmodem-like" part 
> of what I describe above?  Would a bounty raise any interest?

As I said before, I think the work is already being done.  And for what 
it's worth, the monthly $30 or $40 summed over years is a petty amount 
compared to the necessary development cost of the kinds of technologies 
you're discussing.  You'll gladly pay $40 monthly for life than need to 
pay $100K to develop this stuff.

> A little 
> more searching today turned up this:
>
> http://www.gouloum.fr/code/sm/sm.html
>
> Which is REALLY close to what I need...

And note that it uses spandsp (albeit a newer snapshot than iaxmodem 
currently uses), so iaxmodem is therefore not far-off from where you 
claim to need it to be.

Thanks,

Lee.