[asterisk-users] alarm POTS lines

[Kevin P. Fleming]

On 12/02/2010 10:58 AM, Jeff LaCoursiere wrote:

> But it seems to me that there should be a solution much like our "fax
> relay", where we literally accept the fax call over the local LAN, produce
> a PDF file, transfer it to the central switch which then dials it back out
> over a T1.  In that case the only "modem over VoIP" is on their local LAN,
> which has performed well for us.

It can't be relayed; the alarm protocol is interactive, so a solution 
analogous to T.38 must be used.

> I would love to see a DSP "modem" that could answer an asterisk channel,
> send the data stream over TCP to some remote asterisk, which could then
> "relay" the stream by making an outbound DSP modem call on a PSTN trunk.
> Has anyone attempted anything like this?

Guess what? There is already a standard for this, called V.150, Modem 
over IP. It certainly would be possible to implement this sort of thing 
for Asterisk, and some small steps in that direction have been taken way 
in the past... I'd suggest doing some Google searching to see what you 
can find.

> So hoping this will spark some comments on the concept in general, and
> really hoping someone has actually tackled something similar.  It could
> open up a nice niche for even residential customers with expensive POTS
> lines dedicated to alarm systems.

Or those customers could switch to cell-connected alarm panels (which 
are rapidly becoming less expensive and provide reliability benefits), 
or even IP-connected alarm panels. Either choice would be better in the 
long term than trying to convince an ancient alarm panel's modem to work 
over a packet network.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
skype: kpfleming | jabber: kfleming at digium.com
Check us out at www.digium.com & www.asterisk.org