We have two simplisafe systems. I love them. Bought the first one for my shop because ut has no phone line and liked it so much we bought another for the house, canceled the previous house alarm and phone line. Both units are cellular. I have it set up where I get a text any time anything happens. The text tells me which sensor went off it was a motion, door, which one, etc. The call center is super quick also. When I have accidentally set the alarm off I had a call in about 15 seconds. I can't say enough good about it and for 19.99 a month you can't beat it. The only downside is everything is wireless and takes batteries. AA I think. They last a good while but if you have a lot of sensors you might have a dozen things to change batteries in every couple of years. The alarm warns you when batteries getting low.