The Trigger: 0–3 Seconds
An alarm event starts at the sensor. A door contact separates, a motion detector sees movement in its field of view, a glass-break sensor hears the acoustic signature of breaking glass, or smoke particles reach a detector's sensing chamber. The sensor transmits wirelessly (or over wire) to the alarm panel — typically within 1–2 seconds of the event.
The panel checks the zone status against its programming. If the system is armed and the zone is active, it starts the entry delay countdown (if configured) or triggers an immediate alarm. Most installations use a 30–45 second entry delay on the primary entry door and immediate trigger on all other zones.
The Entry Delay: 0–45 Seconds (if configured)
If you arm the system and then open the front door to disarm it, the entry delay gives you time to reach the keypad before the alarm transmits to the central station. During this window, the panel is in "alarm pending" state — the keypad is beeping, but no signal has gone out yet.
If the correct code is not entered before the delay expires, the panel switches to full alarm: siren activates, and the signal transmits immediately. This is why most professional installers set the entry delay no longer than 45 seconds — longer delays give intruders time to disable the panel before transmission.
Some DIY systems ship with 120-second or longer entry delays. This gives an attacker nearly two minutes to find and disable the panel after entering. Professional installers set entry delays to the minimum practical time — typically 30–45 seconds.
Signal Transmission: 3–8 Seconds
Once the panel triggers, the encrypted alarm signal travels over the cellular or IP path to the central station. For cellular, this typically takes 3–5 seconds. For IP, 2–10 seconds depending on network conditions. The signal includes: subscriber account number, zone identifier, alarm type, and a tamper-check token.
The central station's receiving system logs the signal with a millisecond timestamp and routes it to an available operator's screen.
Operator Response: 8–45 Seconds
A UL-listed central station is required to acknowledge incoming signals within defined time windows. An operator sees your account, the triggering zone, the response instructions you specified during installation, and your contact list.
For a burglary alarm, the operator's first action is typically to call the premises — giving you a chance to cancel if it's a false alarm. This call happens within 30 seconds of signal receipt in a properly staffed station. If you answer and give the correct password, the alarm is cancelled. If there's no answer, or the password is wrong, dispatch proceeds immediately.
Your account should have a normal cancellation password and a separate duress code. If you're being forced to cancel the alarm, give the duress code — the operator will cancel verbally but dispatch police silently. This is a standard feature of professional monitoring accounts.
Dispatch: 45–90 Seconds
Once the operator determines dispatch is warranted, they contact the appropriate emergency services — police, fire, or EMS — with your address, the alarm type, and any video confirmation details. This process takes 15–30 seconds depending on the jurisdiction's dispatch channel.
The operator simultaneously begins calling down your contact list, continuing to notify family members, neighbors, or property managers while police are en route. Every call, cancellation attempt, and action is time-stamped and logged in the central station's records.
After Dispatch
The operator remains available to relay additional information to police as they respond — whether new camera images have appeared, if an additional zone has triggered, or if a contact on the list has provided information about the situation. The log created during this event is available to you after the fact and can be provided to police or insurance companies if needed.
If police respond and find no evidence of a break-in, the alarm is classified as unverified. Your alarm permit (required in most St. Louis jurisdictions) logs the event. Excessive unverified alarms can result in municipal fees — which is why video verification and properly set entry delays reduce real costs over time, not just false alarm stress.
Total Time: Under 90 Seconds
From sensor trip to police notification: in a professionally monitored system with a UL-listed central station, the entire sequence runs in under 90 seconds. This figure assumes immediate operator pickup and no delays in premises verification. With video verification enabled, the process can be even faster — because an operator who can visually confirm an intruder on camera moves directly to dispatch without the premises call step.