There are three main types of burglar alarm available to UK homeowners, and they are not interchangeable. A bells-only alarm makes noise when triggered; a monitored alarm calls someone; a smart alarm lets you manage everything from your phone. Understanding the differences between burglar alarm types in the UK — including what each actually does when triggered, what it costs to install, and whether it qualifies for police response — is the starting point for choosing the right system for your home.
A bells-only alarm — also called a local alarm — triggers an external sounder (the box on the front of your house) and sometimes an internal siren when activated. That is all it does. No call is made, no message is sent, and no one is notified unless they happen to hear the alarm and take action.
Bells-only systems are the most common type fitted in UK homes. They work as a deterrent — many burglars will abandon an intrusion when a siren activates — and they alert neighbours. Their limitation is that urban areas have become so acclimatised to alarm noise that most people ignore them, and a determined burglar knows he has several minutes before anyone is likely to intervene.
The practical case for bells-only is that it is inexpensive to install, has no ongoing monitoring costs, and in quiet residential areas where neighbours do pay attention, it provides meaningful deterrence. It is not suitable for properties that are regularly left empty for extended periods, properties in areas with high background alarm noise, or where police response is a priority.
Bells-only alarm systems are available as DIY kit (Pyronix Enforcer, Texecom Premier, Yale HSA6400) or professionally installed. The key components are: a control panel, PIR motion sensors (typically 2–4 for a three-bedroom house), a door contact for the main entry point, a visible external bell box, and an internal sounder. The bell box is as important visually as it is acoustically — a clearly mounted box on the front of the property deters entry before it even begins. A quality bells-only system from a reputable installer costs £400–£900 all-in, with no ongoing fees beyond an optional annual service.
A self-monitored alarm adds a notification layer. When triggered, the system sends an alert — via phone call, SMS, or app notification — to a nominated contact list. This might be you, a family member, a trusted neighbour, or a combination. You then decide what action to take.
This category includes traditional auto-dialler systems (which call a pre-programmed number) and modern smart alarm systems (which send push notifications to an app). The principle is the same: you are your own monitoring centre. The system is only as useful as the speed and reliability of the people on your contact list. If your phone is on silent and the alarm triggers at 3am, a self-monitored system will not help.
Self-monitored systems typically have no ongoing subscription cost beyond the app fees (which are often free or low), making them cost-effective. Systems from Ring, Arlo, and similar brands sit in this category. Our guide to the best home alarm systems in the UK covers the leading DIY self-monitored options with test results and honest assessments.
A professionally monitored alarm connects to an Alarm Receiving Centre (ARC) — a staffed facility that receives alarm signals 24 hours a day. When the system triggers, the ARC operator follows a predetermined response procedure: calling the keyholder, contacting police, dispatching a physical response, or a combination depending on the grade and contract.
This is the only alarm type that can trigger a police response directly, and only when the system meets the required grading standard. Professional monitoring typically costs £15–£40 per month on top of installation costs, and requires an annual service from a qualified engineer. For properties with high-value contents, for landlords managing rental properties, or for anyone whose primary concern is an actual response rather than deterrence, professional monitoring is the only category worth considering.
The grading of an alarm system determines whether police will respond to it. In the UK, police forces do not respond to calls from unverified alarm activations — too many false alarms made direct police response unworkable. Instead, police response is only available to alarm systems that are:
The main grades relevant to domestic properties are:
Our in-depth guide to NSI approved alarm systems explains the approval process and how to verify whether a company genuinely holds NSI or SSAIB certification — a crucial check, since some companies falsely claim approval status.
The cost of a burglar alarm depends on the type, the number of detection zones, whether it is wired or wireless, and whether installation is by a qualified engineer or DIY. Here is an honest summary of what to expect:
| Alarm type | Installation cost | Ongoing cost (per year) | Police response eligible? | Best for |
|---|---|---|---|---|
| Bells-only (DIY) | £100–£400 | £0 | No | Deterrence on a budget |
| Bells-only (engineered) | £400–£900 | £80–£150 (annual service) | No | Better deterrence, reliable hardware |
| Smart self-monitored | £150–£600 | £0–£120 (optional app sub) | No | Tech-comfortable homeowners, rental properties |
| Professionally monitored (NSI/SSAIB) | £600–£2,000 | £180–£480 (monitoring + service) | Yes (Grade 2+) | High-value properties, remote homes, police response |
These figures align with Which? burglar alarm buying guide cost data. Prices at the lower end of each range typically reflect smaller systems in straightforward properties; larger or complex installations sit at the higher end. Always get two or three quotes before committing to a professionally installed system.
It is worth being clear about what police response to a burglar alarm means in practice. UK police forces operate a Unique Reference Number (URN) system. To obtain a URN, your alarm must be Grade 2 or above, installed by an NSI or SSAIB-approved company, and connected to an approved ARC. The ARC holds the URN and contacts police when two conditions are met:
Even with a URN, police response is not guaranteed. Police forces prioritise calls by risk, and an alarm call may receive a delayed or no response if resources are committed elsewhere. The URN system gives you access to the response queue — it does not guarantee response time. The Home Office guidance on police response to security systems sets out the current policy framework.
Smart alarm systems occupy a wide spectrum — from basic DIY kits to Grade 2 systems with professional monitoring. Here is how the main players compare:
Ajax is a professional-grade wireless alarm system that has become well-regarded in the UK installer market. It is Grade 2 certified, can be connected to an NSI-approved ARC for full police response, and offers a well-designed app with detailed event logs. Ajax is installed by trained engineers rather than DIY — expect costs of £800–£2,000 fitted, with monitoring added on top. For properties where police response is genuinely needed and a modern wireless system is preferred, Ajax is worth the investment. See our NSI-approved alarm guide for more on how Ajax fits into the approved installer framework.
Ring Alarm is the most widely known DIY smart alarm in the UK. It is wireless, self-installed, and integrates with Ring cameras and doorbells. Ring offers optional professional monitoring through its Ring Protect Plus subscription (around £10/month). Ring Alarm is not NSI/SSAIB graded and does not provide police URN eligibility — its monitoring service will call your keyholder list and, at their discretion, contact emergency services, but this is not equivalent to an approved ARC response. Ring suits homeowners who want convenient self-monitoring and integration with a camera ecosystem, but should not be relied upon as a replacement for a properly graded monitored alarm. Our assessment of outdoor security cameras covers the Ring camera range in more detail.
Verisure is a professionally installed, professionally monitored system. It is NSI Gold approved and includes a physical response capability — Verisure employs its own response officers who can attend your property within a target time rather than waiting for police. The system includes cameras integrated with the sensors (which enable confirmed-by-video alarm activation), a tamper-proof GPRS communicator, and a 24-hour monitoring centre. Verisure costs are at the higher end — typically £300–£600 upfront and £30–£45/month ongoing — but it is one of the few systems that combines Grade 2 approval, visual confirmation, and a proprietary physical response.
The right answer depends on your priorities, property, and budget. Here is a practical guide:
Whatever system you choose, physical security at doors and windows is the foundation — an alarm does not prevent entry, it responds to it. Our guide to window and door security covers the physical hardening measures that work alongside any alarm type, and our home security on a budget guide shows how to layer deterrents cost-effectively if funds are limited.
A professionally installed and monitored burglar alarm — particularly one with NSI or SSAIB approval — can attract meaningful discounts from home insurers, sometimes 5–15% off annual premiums. Bells-only and ungraded smart alarms may attract smaller discounts or none at all, depending on the insurer. When comparing alarm quotes, ask specifically about insurer acceptance and whether the monitoring company will provide documentation of the grade and installation for your insurer. On a high-value property with substantial contents insurance, the annual saving on premiums can materially offset the monitoring subscription cost.
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