What happens if I am on the phone in the event of an alarm?    If you are on the phone extension that the base-station is plugged into, the base station will interrupt your call and seize the phone line to call the fire department.  If you are on another extension away from, the base-station, FireArrest™ will be unable to call the monitoring station.  When you hang up, the base station will redial the monitoring station.  Remember the primary purpose of any smoke alarm system is to alert the family to evacuate the premises immediately.