Control Products FA-B-CCA Basic FreezeAlarm Calls any one phone number when temp drops below 45 degrees in the home. Plays a voice message warning of falling temperatures at the monitored location. Continues to call until the alarm is acknowledged. Operates on any phone system that provides a dial tone (land line, DSL, VOIP). Runs on battery power, so it can operate during a power failure (as long as the phone system is operating).