Alarm Signalling and Police Response Explained
How a monitored intruder alarm gets its message out, and what has to be in place before police will respond
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Alarm signalling is the route an intruder alarm uses to tell someone it has been triggered. A siren on its own only alerts people within earshot. A signalling device sends the alarm to a monitoring centre, a keyholder or your phone, so someone can act even when the building is empty.
This guide explains the main signalling paths, why the switch from analogue to digital phone lines matters, how intruder alarm grading works and what is needed before an alarm can have police response. For the wider choice between bells only, app alerts, diallers and monitoring centres, see our page on [alarm monitoring options](/alarm-monitoring).
We are a team based in Chatham working on alarms across Kent and South East London. If your monitored alarm has stopped communicating, our page on an [alarm signal not reaching the monitoring centre](/security-faults/alarm-monitoring-signal-fail) covers the likely causes.
What You Will Usually Notice
How the alarm signal travels
When a detector is triggered, the panel passes the event to its communicator. The communicator sends a coded message over its signalling path to the receiving monitoring centre, which identifies the site and the zone. Operators then follow the agreed plan for that site, which usually begins with calling keyholders.
Many systems also send regular test signals so the monitoring centre knows the path is healthy. A missed test is often the first sign that a line, SIM or router change has broken the connection.
Confirmed alarms and false alarms
Monitoring centres usually look for confirmation before treating an alarm as a likely intrusion, for example a second detector triggering in sequence, or audio or video evidence. Confirmation reduces false calls, which matters because repeated false alarms can put police response at risk. Good detector positioning and regular servicing help keep false alarms down, and our alarm servicing covers the detectors, batteries and signalling together.
Safe Checks You Can Do Yourself
Find out how your alarm signals today
Check your paperwork or monitoring contract for the type of communicator. It may use a phone line, broadband, a mobile SIM or a combination.
Note any recent line or router changes
A new router, a broadband switch or a move to a digital phone service can stop older communicators working without any warning on the keypad.
Ask the monitoring centre for your last signal
Monitoring centres log test signals. Asking when they last heard from the panel is a quick way to confirm the path is working.
Read your insurance wording
Look for any mention of grade, monitoring or police response. Those words decide what the alarm needs to be.
Burglar alarm repairs
- Alarm fault finding
- Component replacement
- System health checks
What Normally Causes It
Single-path signalling
A communicator using only one route, such as a phone line, has no fallback if that route is cut or fails. Single-path systems are simpler but leave a gap.
Dual-path signalling
Dual-path communicators send the alarm over two routes, usually broadband and a mobile network. If one fails, the other carries the signal, and the loss of a path is itself reported to the monitoring centre.
The digital phone line switchover
The UK's analogue phone network is being retired in favour of digital lines. Older communicators that rely on a traditional analogue line may stop signalling reliably, so it is worth checking how yours connects before the change reaches your property.
Intruder alarm grading
Alarms are graded from 1 to 4 under the European standard used in the UK, based on the knowledge and tools an intruder is expected to have. Most homes sit at grade 2, while higher risk commercial premises are often specified at grade 3 or above. The grade affects the equipment, tamper protection and signalling.
What police response requires
Police response is not automatic. Under the national police policy, the alarm must be installed and maintained by a company certified by an independent inspectorate, monitored by an approved monitoring centre and registered with the police, with keyholders who can attend. Response can be withdrawn after repeated false alarms.
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Covering Chatham, Medway, Kent & South East London
When to Stop and Call an Engineer
Keeping it from coming back
Have the signalling tested as part of regular servicing, keep your keyholder list up to date, and check the communicator whenever your broadband, router or phone service changes.
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Frequently Asked Questions
Alarm Signalling and Police Response Explained: common questions
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