my security alarm works with my digital phone service. I use ADT and the system is quite few years old. I spoke to my isp and the security people and what ever magic was needed happened. I know it works as two weeks ago my alarm went off at 3:00a.m. (I forgot to turn off the motion dectector in the living roomand the dogs set it off) and the alarm company called before I got my glasses on and the gun out. It was a short night after that.