I've had Protection One alarm system in my home for about 8 years. I am very happy with them. I just recently had an issue with my Cox land line which connects with my Protection One box, and then a few days later the cell backup on the system. I called them today and they came out today!! Not only did they replace the cell backup and the battery, but the technician that came out also fixed my land line!!! He really was not responsible for the land line but wanted to get it working for me.
I have to say, for the 8 years I've had them they've been great. I get a call from Protection One if my BF comes over and forgets to turn off the system after he comes in the house.
I used to have ADT and they were pretty good too. But Protection One is superb!!