"But if they know what they are doing, will not stop them. I had an alarm and these guys first cut my phone line from the outside the house so the alarm can't call the station. "

Today alarm systems have cellular back up. If for any reason phones go out it will still dial the police. I think the charge is 11 dollars extra a month for that. Maybe more today. Also they have cameras that can record anyone approaching before they even get to your house. But I agree if anyone wants to get in they will.

Barry