Treading Today’s POTS Minefield


Security Sales & Integration (SS&I) magazine, July 2017 issue

LET ME BEGIN by getting a little sentimental for a moment. When I started and built RMR (recurring monthly revenue) in my alarm company back in the 1970s, there were two key elements; the newly introduced programmable digital dialers, also known as DACT’s (Digital Alarm Communicator Transmitter) and POTS (Plain Old Telephone Service), also known as PSTN (Public Switched Telephone Network). Now I am sad, yet in a way excited, to truly say I can see the sunset of this technology.

What I’d like to focus on here are some of the technical dangers technicians are presently facing in the industry’s transition from POTS to IP (Internet Protocol). The chief culprit is a technology called VoIP (Voice over Internet Protocol), which appears to the layman as new version of POTS, but is far from it. Technicians think they are programming a DACT for a POTS line only to find out the telco provider has
switched some of the main trunks to VoIP. You don’t know when this may happen, and it can cause intermittent failure of your critical, sometimes life-safety, communications. It’s a communications minefield.

Recently I had stopped over at one of my favorite security industry trade talk online hangouts, Ken Kirschenbaum’s Alarm Articles. Many of you also know Kirschenbaum, an industry Hall of Famer, from his monthly Legal Briefing column in SSI magazine. To give you a sense of what’s going on in the field, this month I’d like to share some of these online conversations techs are having on current issues with the intermittent status of POTS.

Jeff Schneller, Acme Fire Alarm Co.
“The past several months we have been experiencing DACT telephone line communications problems. The DACTs are not communicating with the central station and fail. When they fail the kiss-off light remains on but does not signal the panel there is a problem. Tech support from the manufacturer and the central station all feel it is phone line issues.”

Douglas Emery, Iverify
“To combat this I have been recommending that on all new fire alarm systems my company installs we have a secondary line of a different technology (cellular/network/radio). I agree that it is time to start recommending ‘alternative communication’ especially for new systems.”

Dan Zeloof, Inner Security Systems
“We found out that the provider could program their equipment to route the call to whomever is cheaper. We’ve instructed our provider to use AT&T routing once we found out that there is
such a thing as being able to choose. We get a spreadsheet of all our calls and figure out who the carrier was on a misdirected signal.”

Mike Fletcher, Florida Alarm School LLC
“The best fix available today seems to be asking the provider to configure the VoIP or digital line as a fax line. This means the carrier will select a codec [coder/decoder] protocol that does not use any fancy compression or features to conserve bandwidth and is more likely to code and decode the fax and/or dialer data accurately. THIS IS A BAND-AID ONLY!!!”

Ron Wies, Monitoring America Alarm Co-Op
“Alarms communicate just fine on VoIP. However, when a call is routed with no control the alarm communication may transition back and forth between SIP [VoIP] and TDM [POTS]. It’s this transition between the two technologies where the problems occur. Packets are dropped and the communication is scrambled. We have contracted with a telephone provider who offers controlled SIP service. Now when one of our alarm monitoring phone numbers are dialed the call is routed SIP from subscriber to our alarm receiver. We get a clean signal and no longer have communication problems regarding VoIP or POTS sunset issues.”


Another example of POTS lines going away and going fast.

Download the AES guide, Why Mesh Radio is Better.

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