some things to consider, was out of the country with the wife and dad was watching the house.
He couldn't figure out how to use the remote arm disarm key fob that I have him and forgot to give him the code.
Alarm goes off, so he goes into the garage and flips the master power from the breaker box...waits five minutes...turns back on power. Alarm rearms and goes off again. This time he was outside, goes back in hits power again. Waits 5 minutes and it resets without going off.
Now upon entry you have about 30 seconds or more to hit the shut off code, you can easily get to the breaker box if you know where it is located. (usually in the garage)
Police were called on the second time that it went off, took them over 30 minutes to arrive (dad was there for 20+ and left)
Many telephone companies use digital phones now that go through the internet connection. When the power is shut off the modem dies. If you have no cellular backup there will be no call to authorities. In addition a quick clip of the unprotected outside wire (usually easily seen and exposed on most houses) will make a quick end to this.
Most alarm systems will not work without power soo, just something for y'all to think about. In addition motion detectors also die with the cut of the power as well. Windows usually have to be opened to set off the alarm, so if you can avoid the motion detectors and just break the glass without opening the window and climbing through most alarms will not trip. If you have do not have motion detectors well you are just SOL.
Just some food for thought...