How a Central Station Handles a Signal, from Panel to Dispatch

Why this matters

When a customer says "the alarm went off and nobody came for twenty minutes," the dealer gets the call, and the dealer usually cannot explain where the twenty minutes went. Some of it was on the panel, some on the network, some in the operator's queue, some on the phone with the customer's call list, and much of it after the police took the call. Knowing where each delay lives is how you answer that customer honestly, and how you find the delays that are actually yours to fix: a call list nobody updated, an entry delay set far longer than the door needs, a zone description that tells the operator nothing.

The path of one burglary signal

 PREMISE           PATH          CENTRAL STATION
 sensor trips
     |
 panel: entry delay,
 then abort window
     |
 communicator --> cell, IP --> receiver: decodes
                  or phone     account + event
                  line             |
                               automation software:
                               adds address, zone
                               name, call list,
                               permit, instructions
                                   |
                               operator queue (fire,
                               panic, then burglary)
                                   |
                               operator calls premise,
                               then the call list
                                 |             |
                               CANCEL       DISPATCH
                               (passcode    (police
                                given)       agency)

Every arrow in that drawing is a place where time passes. The sections below walk it left to right.

On the panel: the delays the dealer programs

Entry delay. On a door programmed as an entry zone, a trip starts a countdown so the person coming in can reach the keypad. Nothing is sent during it. If the code is entered, nothing is ever sent.

Abort window. On panels built to the ANSI/SIA CP-01 false alarm standard, after the entry delay runs out (or an instant zone trips) the panel sounds the alarm but holds the transmission for a further short window. A disarm inside the abort window means nothing is sent, and on most panels the keypad shows that the alarm was aborted. See related: False Alarm Reduction Features in the SIA CP-01 Standard.

Cross zone and swinger rules, where programmed, can also hold or suppress a signal. Fire, panic and hold-up zones are normally exempt from all of these delays.

So before a single byte leaves the house, a burglary through an entry door already spends the entry delay plus the abort window. Those two figures sit in the panel's programming, and the dealer chose them.

On the network: the communicator

The communicator turns the event into a message in a reporting format the receiver understands and sends it over its path: a cellular radio, the home's internet connection, or a phone line. A cellular or IP path is typically delivered in seconds. A phone-line dialer has to seize the line, dial and handshake, which takes longer, and fails outright on many modern voice services. Communicator types, network sunsets and backup paths are covered in 'Cellular Backup and Alarm Communicators'.

The receiver acknowledges the message. If the panel does not get the acknowledgment, it retries and may fall back to a backup path, which adds time but is the reason a dual-path panel gets through when one path is down.

At the receiver and the automation software

The receiver decodes the account number and the event code. The automation software then does the work the operator depends on: it looks up the account and attaches everything the dealer entered when the account was set up.

What the operator sees for a burglary signal, if the dealer did the setup right:

• the account and premise address, with cross streets or gate code if entered;
• the event (burglary alarm, entry/exit zone) and the zone number with its zone description;
• the call list in order, each with phone numbers and whether they hold a passcode;
• the passcode on the account and any duress word;
• the alarm permit number, where the local agency requires one on the dispatch call;
• special instructions: dog in the yard, vacation dates, "call cell first";
• the recent signal history, so the operator can see an opening an hour ago or an alarm that already restored.

The zone description is the field dealers most often get wrong. "ZONE 4" tells the operator nothing. "Rear slider, family room" tells them what to say to the police and what to ask the customer. A description written at install takes seconds and helps every alarm for the life of the account.

In the queue

Signals queue by priority. Fire, carbon monoxide, medical and panic or hold-up come ahead of burglary, and burglary comes ahead of troubles such as an AC loss or a low battery. A burglary signal arriving during a regional storm, when hundreds of panels are reporting power failures and some are reporting fire, waits behind every higher-priority event in the queue. Most of the time the wait is short. On a bad night it is the biggest single block of time in the whole path, and it is not something the dealer can program away.

The operator's calls

For a burglary signal the operator follows the account's action plan, which in most stations starts with a call to the premise. Someone who answers and gives the passcode can cancel. No answer, or an answer without the passcode, moves the operator down the call list.

Many jurisdictions require, and most stations practice, enhanced call verification: at least two calls to different numbers before a burglary dispatch. Each call that rings out is time added, which is the trade the jurisdiction made to cut false dispatches. How verification methods compare, including video and audio, is the subject of 'Alarm Verification Methods: Calls, Video and Audio'.

Fire signals are not held for two-call verification. NFPA 72's household chapter permits a station, in substance, to verify a household fire signal only if that does not delay reporting beyond a short limit the adopted edition sets, and many stations simply dispatch the fire service and then call the premise.

Dispatch, and what happens after

To dispatch, the operator contacts the agency that serves the address. Historically that has meant a phone call to the agency's dispatch line, where the operator waits in that center's own queue and reads the details aloud. Where both sides support it, the ASAP-to-PSAP interface (an electronic link between monitoring centers and public safety answering points, standardized by APCO and The Monitoring Association) sends the same details as data, which removes the hold time and the read-back errors.

After the handoff, the response is the agency's. Police agencies triage unverified burglary alarms against everything else they have, and in many places an unverified residential alarm is a low priority call. The dealer and the station control nothing past this point, and an honest answer to the customer says so.

The operator then finishes the action plan: calls the rest of the list to tell someone a dispatch is under way, logs everything, and records any cancel that comes in later.

Worked example: where nineteen minutes went

A customer complains that a back-door alarm at 02:10 got "no response for almost twenty minutes." The dealer pulls the panel programming and the station's operator log for the event. The times below are this account's actual programming and this event's log, not standard values.

Read the table by who owns each row.

The dealer owns the first two rows, 1 min 15 s. A 45-second entry delay on a back door eight steps from the keypad is longer than it needs to be. Shortening it is a programming change, and its effect on the customer must be tested. See related: How to Program Entry and Exit Delays and Time Them.

The network owns about 5 seconds. Nothing to fix.

The station owns the queue and the calls, 5 min 40 s (3 min 10 s plus 1 min 20 s plus 1 min 10 s). The queue was a storm-night surge. The two calls rang out because the house was empty and the homeowner was on an overnight flight with the phone off. The call list held only those two numbers; the homeowner's adult son, who lives ten minutes away and has a key, had never been added. That is a dealer-and-customer fix, and it is the most useful thing found.

The agency owns 12 minutes (4 min 30 s on hold plus 7 min 30 s to arrival). If the station and the agency both supported the electronic dispatch link, most of the 4 min 30 s would go away. The 7 min 30 s is the agency's priority for an unverified residential alarm.

Adding the owners back up: 1:15 plus 0:05 plus 5:40 plus 12:00 is 19:00, which matches the last row. The customer's "almost twenty minutes" was accurate, and about 63 percent of it (12 of 19 minutes) happened after the station handed off.

What the dealer did: cut the back-door entry delay to the shortest time the household could reliably disarm in, added the son to the call list as the second call, with a passcode of his own, and talked to the customer about verification. A video-verified alarm would have given the operator something to report beyond "alarm on the back door," which some agencies treat as a higher priority.

What changes the picture

• A fire or panic signal. No entry delay, no abort window, no two-call verification before dispatch, and the highest queue priority. The same path takes a fraction of the time.
• A phone-line communicator on a modern voice service. The transmission row can stretch to minutes of retries or never complete. The station sees nothing, so the operator's clock never starts.
• A self-monitored system. There is no operator. The path ends at a push notification on the customer's phone, and every step after that is the customer's.

How to use this on the next complaint

Pull three things before calling the customer back: the panel's entry and abort programming for the zone, the station's operator log with timestamps for the event, and the call list as it stood that night. Build the table above from them. It turns a complaint about the alarm company into a list of fixes with an owner on each line.

References

• ANSI/SIA CP-01, Control Panel Standard: False Alarm Reduction (the abort window)
• APCO and The Monitoring Association, ASAP-to-PSAP alarm data exchange standard
• NFPA 72, National Fire Alarm and Signaling Code, household chapter, in the edition adopted by your jurisdiction (household fire signal verification)
• See related: False Alarm Reduction Features in the SIA CP-01 Standard
• See related: Alarm Verification Methods: Calls, Video and Audio
• Cellular Backup and Alarm Communicators