The short answer
A bells-only alarm sounds a siren and flashes a strobe at the property when triggered; it relies on neighbours or passers-by to react and carries no ongoing fee. A monitored alarm also signals a 24/7 Alarm Receiving Centre (ARC), which can call you, a nominated keyholder or — where the system qualifies — request police attendance, in return for a subscription of roughly £15–£45 per month. The key practical difference is that police response normally requires a monitored system with a URN and the right grade and certification. Bells-only suits lower-risk homes wanting a deterrent without a contract; monitored suits those wanting a guaranteed response and the insurance and police-response benefits that can come with it.
The choice is really about who responds when the alarm goes off — your neighbours, or a 24/7 centre. Here is how the two compare on what matters: response, cost and eligibility.
At a glance
- Bells-onlysiren on site, no fee
- Monitored24/7 ARC + subscription
- Subscription~£15–£45 / month
- Police responseneeds a monitored system
- Best fordeterrent vs guaranteed response
How the two compare
A bells-only system is the simpler option: when triggered it makes a loud noise and shows a flashing beacon, acting as a deterrent and alerting anyone nearby. There is no contract and no monthly cost, but nobody is guaranteed to respond. A monitored system adds a signalling link to an Alarm Receiving Centre staffed around the clock. Depending on the contract, the centre can phone you, call a keyholder, or — for a qualifying system — request a police response. That round-the-clock cover is what the monthly subscription pays for.
| Feature | Bells-only | Monitored |
|---|---|---|
| On-site siren | Yes | Yes |
| 24/7 ARC response | No | Yes |
| Ongoing fee | None | ~£15–£45 / month |
| Police-response eligible | No | Yes (with URN & grade) |
General comparison for guidance. Sources: trade cost guides and NSI/SSAIB guidance.
How to choose for your home
- Want a deterrent without a contract? a bells-only alarm gives the siren and signage with no monthly cost.
- Want a guaranteed response? a monitored system means a 24/7 centre acts when it triggers, even when you are away.
- Need police response? that normally requires a monitored, certified system with a URN — bells-only does not qualify.
- Want the best chance of an insurance saving? a monitored, professionally certified system is more likely to satisfy an insurer's conditions (see the insurance page).
Not sure which type suits you?
We'll match you with a vetted alarm installer who assesses your property and risk and explains honestly whether a bells-only or monitored system fits — with the monitoring cost set out clearly.
Frequently asked questions
What is the difference between a bells-only and a monitored alarm?
A bells-only alarm just sounds a siren at the property and relies on people nearby to react, with no ongoing fee. A monitored alarm also signals a 24/7 Alarm Receiving Centre that can alert you, a keyholder or request police response, in return for a monthly subscription of roughly £15–£45.
Do I need a monitored alarm to get a police response?
Generally yes. Police attendance normally requires a monitored system with a unique reference number (URN), which in turn needs the right grade of system and certification — a bells-only alarm does not qualify.
Is a monitored alarm worth the monthly cost?
It depends on your priorities. Monitoring buys a guaranteed 24/7 response and can help with insurance and police-response eligibility; a bells-only system is a lower-cost deterrent with no contract. Weigh the ongoing fee against the response you want.
Sources & further reading
Figures on this page are typical UK ranges drawn from published sources and depend on your specific property and system. They are guidance, not a quotation.