Anyone have ADT and get an FC error?

[Minnie824]

Last night during a nice peaceful sleep, we were awoken to the sound of our ADT alarm going off. It had a message of 'FC' and I called and they said since its connected to our cell phone, not our land line, there was some issue with that and to bypass it. So, we did that, got back to sleep, turned off the alarm in the morning now, and it went off again, same error. This time I called again, and she said it could be our backup? So we may be able to get someone to come take a look at it. Is anyone familiar w/this? Any ideas what the issue could be? We were able to arm the alarm w/the bypass, but I don't want to have to keep doing that. Thanks.