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Will VoIP (e.g. Vonage) or Comcast digital phone affect my alarm? - Short Answer - yes it can.

Just as people have changed from dial up internet service to broadband (DSL or Cable being the most popular), a lot of customers are changing their phone service form the old standard of Qwest or Verizon to either Comcast digital phone, VoIP (Voice over Internet Protocol) or eliminating their phone service entirely and using only their cell phones.  When these changes are made, the security system, can no longer communicate alarms to the central station.

VOIP is short for Voice Over Internet Protocol.  This is a service that some people are beginning to use for their phone service instead of their local phone company.  Most VoIP services are not compatible with security systems.  If you are using VOIP for your phone service and your security system is tied into that phone line, you may not be monitored.


There are two types of Digital Phone service available.  That provided by your cable company (Comcast) referred to as Cable Telephony, and that provided by true V.o.I.P.  providers (Vonage is one example).


Cable Telephony

Technically the digital phone service provided by Comcast is VoIP. But cable telephony works because they use their network and never go out over the internet.  If a call gets out of their network they will then transfer this call to another phone provider to complete the call.  Therefore this type of communication works well with alarm communications.


Other V.O.I.P. Providers:

Voice over internet protocol provided by other providers differs from cable telephony because they actually use the internet to transfer phone information.  This protocol is not compatible with digital alarm communications.


How V.o.I.P works;


It must first covert the analog signal into a digital format using a compression method.  After compression, the signal is then translated to a series of internet packets that can be transmitted over the I.P. Network.  This process is then reversed at the end.


Those VoIP providers that use the internet not a controlled network are subject to the faults of the internet.  For instance if the internet is slow, this will cause the digital communications to slow down as well, therefore if you send a digital signal over the network, the timing is thrown off.  The arrival time of the individual packets could be constantly changing.  Most alarm panels send 1 alarm signal in 1.4 seconds; if the internet is slow it could take 4-5 seconds for a signal to be transmitter and reassembled, thus causing communication failures.


When you lose power your phone service is also removed.  This is because your modem needs power to operate.  A UPS may provide temporary power, if it is properly connected.


Also when the VoIP provider installs your service they generally cut the phone line at the service box.  They then connect the modem to the phone wiring in a different part of the residence, which back-feeds the phone connection.  Unfortunately when this happens the panel performs its line seizure and it seized itself and never dials out.


Regular testing of your alarm system is extremely important to assure its continued proper operation. 


What are my options if I want to use VoIP for my phone service? 


Currently there is Cellular and IP based monitoring.  There are also new products coming out that claim to overcome the problems with communications over VoIP lines.


If you have questions please contact Dale at  206 362-6294