We have an ADT alarm system , the other night I heard a neibor saying he could disarm our alarm system .. he tried telling someone ells how to do it .. said it was the 3rd cable to the right or the internet , and tv cable. is this true? .. and , would he have to have access to the basement to do so? .. also .. if disconnected will it set off the alarm. we are scared now that he will enter our home.

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    Yep, though ADT will likely detect the disconnect and take action. blog.frontpointsecurity.com/…
    – isherwood
    Mar 8, 2016 at 20:26
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    ADT will sell you a cellular backup connection if you worry about someone cutting your voice or internet connection. You should make sure your system also has an adequate battery backup system to prevent disabling of the system by cutting power.
    – Johnny
    Mar 8, 2016 at 21:50

3 Answers 3


When an alarm trips, it can send out one or more of three types of alerts:

  • local - an audible alarm rings at the property
  • direct police connection - when the alarm rings, it goes off in the police station itself (rare)
  • central station - an alarm goes to the alarm monitoring company, which then alerts the police in certain circumstances (such as no one answers or fails to give a password following a callback to the house).

Some alarm setups are local only, some remote (police or central station) only, and some are both.

Two things control whether the alarm will go out:

  • is there power?
  • is there a connection to the monitor (if any)

Almost all serious alarms have battery backup to ensure that, even if the power is cut, the basic alarm system is still functional. If there is no battery backup, cutting power lines will nullify the alarm.

Local: Assuming power, AC or battery, a local alarm will ring upon intrusion, regardless of whether cables are cut.

Remote: Connections to police or central stations are most often handled through conventional telephone lines. These may be landline connections or cable/internet connections (if phone service is via the cable system or other internet provider).

Even if power is cut, landline telephone service is often still active, since landlines have their own power feed. But if the telephone line is cut, the signal cannot go out.

Cable/internet phone, on the other hand, relies on modems that need AC power. If power is cut, cable phone does not work. If the cable line is cut, this would also prevent a signal going out.

Cellular remote: Some alarm systems offer a cellular connection. This is like having a dedicated cellphone built into the alarm system. These systems function even if the landline or cable line is cut. They will continue to function even if the AC power is cut (assuming a battery backup, which would be standard on a cellular type setup).

Whether your system would survive a wire attack depends on the type of system you have. Only a cellular based system with a battery backup can withstand all attacks on the wires that feed a property. But many systems will detect a disruption of power or telephone connection, make a call to the owner to see if there is a problem, and alert authorities of the monitor does not get satisfactory assurances. The level of security is a function of how much you are willing to pay and how concerned you are about various levels of risk, and the particular protocols of the alarm monitoring service.

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    Internet connection equipment (media converters, cable modems, etc.) tend to draw very little power, making them great candidates for being put on a small dedicated UPS. This is especially but not exclusively useful if you also have VoIP instead of a regular dedicated landline, and as a bonus can provide lightning protection for the sensitive equipment. I guess you could call this an extension to the "battery backup" discussion.
    – user
    Oct 24, 2016 at 14:44

As others have said, unexplained disconnection of a modern monitored alarm system may be treated as suspicious by the monitoring service, unless an entire neighborhood goes black and they can confirm a wiring problem. (Or may not. Ask your provider.)

If you want a more positive signal, cellular backup is indeed an option. Indeed, there are now systems available which have only cellular connections, and some which can be set up to let you monitor the system from your own phones/tablets if you prefer to DIY rather than contracting it out.


Lots of good answers already but I will add that some installations will include a trap that looks like a phone line but isn't. If it is cut, a silent alarm is triggered via either the real POTS line or a cellular connection.

The ordering of the wiring on the outside of the house is meaningless but it is easy to identify coaxial cables (cable TV/internet) vs the typical 2-pair cable used in most residential settings for phone/DSL.

You can protect these cables with metallic conduit which will make tampering much more difficult. Typically the telco network interface devices (box on the exterior of your house) will be locked as well.

Cameras on this area of your house is another good deterrent.

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