Your alarm system is designed to take in a dial tone from your phone system and send it back out to the phone system. During an emergency, the alarm system disconnects any call in progress on that one line, waits a second for dial tone and then immediately dials your alarm company monitoring service with a signal that says you have a fire, a break in, a holdup, etc.

Have your alarm installer make a test call setting off the alarm while you are talking to someone on the line used for the alarm system. When the alarm goes off, your call should be dropped. If this does not happen, your alarm system is not hooked up correctly, and will not report an emergency if a person, a fax, or a modem is using that line. Your alarm reporting phone line must go into the alarm system and back out to the phone system.

While installing a new DCS phone system in a very expensive prestigious home, we found that the largest alarm company in LA had paralled one wire to the alarm system. If that line had been in use an during an emergency, the emergency call would have gone unreported. Recently we cut over a large building that rents out office suites and found that the dial tone was commoned to the system and the alarm. If anyone had dialed that number and then broken in, the alarm system would not have reported the intrusion to the alarm company. This error in phone line connection to the phone system is common, much too common.

Make a test of your alarm system. While you are speaking on the line used by the alarm system to report emergencies, see if the alarm system disconnects your call to dial the alarm monitoring company and report the alarm panel test call. If your call is not dropped, your alarm system is not hooked up correctly to the phone line.