When I signed up for Monitronics, the contracts states I must have an active phone system at all time. I have a phone system but changed carriers. Monitronics informed me that they couldn't monitor with the phone system I had unless I bought a piece for $350.00 to go with the alarm system. I told them their contract didn't state that - that is just stated I must have a phone system and they needed to rectify the issue, not try to sell me a piece to add to my system. They refused and hung up on me.