Ask The Experts

Doug Richard, President of Midwest Alarm Services, reviews the different forms of fire alarm communication based on the cost over time, reliability, and security.


You often hear the phrase, “back in my day”, well that is how I feel concerning the communication of fire alarm signals. When I first started in this business back in the mid-nineties, there were two methods of communicating fire signals to a dispatch center.

The first method was reverse polarity. This is how fire alarm signals were communicated originally to the fire department. When there was an alarm or trouble, it would reverse polarity, lighting a bulb at the county or local dispatch center. There was no information supplied, just an alarm or trouble signal

The second method was a Digital Alarm Communication Transmitter (DACT). DACT transmitted alarm, trouble, supervisory, low battery and loss of a phone line condition. Two analog phone lines were required and it was a very secure method of transmission.

Fast forward twenty-odd years, and analog phone lines went the way of the horse and buggy. They were replaced with Internet Protocols (IP), cellular dialers, and Advanced Encryption Standard (AES) radios. Each of these methods has its benefits.

IP is the least expensive; however, it is also the least secure. Networks drop out frequently, which can cause a loss of supervision and lead to unwanted phone calls in the middle of the night from the Monitoring Center.

The second method and more secure, but more expensive is communicating via a cellular dialer. The digital communicator transmits signals via the cell phone tower with a priority over standard phone calls. While a cellular dialer is more secure than IP, it will need to be continually upgraded. The 2G network became 3G, which now is switching to 4G and someday will need to be upgraded to 5G. Unfortunately, each upgrade costs money, and any interference via new construction, updates, or other issues can cause loss of communication to the Monitoring Center.

This leads to the last option, which is the most secure and cost-effective in the long run of the three options. The third method is AES radios. An AES radio transmits signals via a mesh network, meeting the dual-path requirement per NFPA 72. The technology is eighty years old and is as secure today as it was back in the forties when it was developed. This form of communication may cost more upfront, but it does not require phone lines or equipment to be updated, making it the most cost-efficient method over time. The illustration below demonstrates how AES radios work.

Midwest Alarm Services installs and services all forms of fire alarm communication. When you take into account the cost over time, reliability, and security of the three forms of fire alarm communication, I would highly recommend considering an AES radio.

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