I have used alarm.com for years. The local installed, installed a GE wireless system, that uses all wireless sensors, even one out in my shed!! It has battery backup and works through satellite (antenna in attic), so even if someone cut the phone wires it still works.
We have had NO false alarms since installed in 2007, and the batteries are all good for 10 years.
I can log in from any computer, or my cell phone, to turn off, turn on the alarm, check all the sensors, and if the alarm goes off it notifies me on my phone instantly, and which sensor tripped.
Oh and the best thing is that they use non-proprietary equipment, so I can choose ANY monitoring service I want. You are not locked into ADT, etc.