By: Nick Markowitz Jr.
Have the days where two phone lines hooked up to a fire alarm Digital Alarm Communicator Transmitter (DACT) become numbered? Personally, I do believe so.
As more and more phone lines go digital--feedeng either a T1 Channel Bank or some other digital technology, like Verizon's FIOS--redundant phone lines are really pointless. In the true analog POTS (Plain Old Telephone Service) days, having two numbers asured that the signal would get through since the chance of both numbers going out at the same time where slim to none.
When we talk about modern digital phone lines, or what is known in the NFPA 72 Code as Managed Facilities Voice Networks (MFVN), when we loose one of them, we loose them all. When the broadband signal that tells the interface device to put out the individual voice paths is lost, all signal paths are lost. This of course includes voice circuits, Internet and phone. So at this point what sense does it make to require two phone lines?
My answer, there is no point.
Ultimately AT&T and other communication corporations want POTS to go away altogether by 2014, and yes this will cause a burden to many devices which require true dialtone to dial out, but luckily there are alternatives available, such as cellular and two-way radio, along with dialer capture units that retransmit the signal over the Internet, known as Internet Dialers. But the bigger question has still not been answered and that is how to safely back-up most digital systems. Most of these systems have no battery back-up to keep them operating. And when they do, it's only for a couple of hours, which will does not comply with NFPA 72. On the other hand, good-old POTS will keep on working.
You say, "No problem, when digital goes out we know its not working as Internet dialers are supervised." But what good does that do when you cannot tell what's going on at the unattended premise when it's a long holiday weekend? Are we really willing to take this kind of chance? More so, will the client be willing to sacrifice the safety of his or her facility and those who work, play, and visit there? Not if they're told--and will you tell them?
This is the price we're going to pay for digital convergence and this weekend of Feb. 6th 2010 is really going to prove out all the disadvantages of digital with snowfalls of 20 to 30 plus inches of snow along the East Coast. Better get out the cell phone and hope it works. And where's that car charger, you may need it to keep the battery in your cell charged so you can stay in communication with critical services if you should need them.