Internetworkers: http://www.ibiblio.org/internetworkers/

[ron thigpen <ron AT fuzzsonic.com>]

possible for GSM if you cloned the SIM card.  not sure how the network 
would react if both connected at once.

given that the revenue model of the home security companies is based 
around recurruing service fees, i'd guess that the cell option was 
contracted through their provider and add'l monthly fee were rolled into 
your security services fee.  if it were roll your own, fees could be 
quite low if you could find the right pre-paid or pay-as-you-go plan.

--rt

David Minton wrote:
> I would doubt it--I was under the impression the alarm hardware had a
> stripped down cell phone-type circuitry built into it. Can two cellular
> devices share the same number?