The short answer

Commercial fire alarm monitoring is the 24/7 connection between your fire alarm panel and an Alarm Receiving Centre (ARC), which calls the fire and rescue service and your keyholders the moment your system activates. The UK’s analogue telephone network (PSTN) is being switched off by 31 January 2027, so any fire alarm that still sends its signal down a copper phone line will stop reaching the ARC. The panel will still sound the bells on site, but nobody outside the building will know. The fix is to replace the old dialler with a digital signalling device, ideally a dual path unit using both the internet (IP) and 4G, commission it, and test that every signal type actually arrives at the ARC. With around four months left and engineers booking up, now is the time to check.

What is commercial fire alarm monitoring?

A monitored fire alarm does two jobs. It warns everyone inside the building, like any fire alarm. It also sends a signal off site, through a signalling device (sometimes called a communicator or dialler) to an Alarm Receiving Centre.

The ARC is a staffed monitoring station that runs 24 hours a day. When your signal arrives, operators follow an agreed response plan: calling the fire and rescue service, contacting keyholders, or both. The ARC also receives fault signals, so if your panel develops a problem at 2am on a Sunday, someone knows about it.

Three parts have to work together:

• The fire alarm panel, which detects the fire or fault.
• The signalling device and path, which carries the message off site over a phone line, broadband, the mobile network, or a combination.
• The ARC, which receives the message and acts on it.

The PSTN switch-off hits the middle part. That is the bit most building owners never think about, because an installer chose it for them years ago.

Is fire alarm monitoring a legal requirement for businesses?

Not in itself. No UK fire safety law says every commercial building must have its alarm monitored by an ARC. Whether you need it depends on your fire risk assessment, the category of your system, and very often your insurer.

Monitoring is normally expected where:

• The building is empty for long periods, such as offices, warehouses and retail units out of hours.
• There is a sleeping risk, such as hotels, care homes and HMOs.
• People would struggle to raise the alarm themselves, such as residents with limited mobility.
• Your insurer has made it a condition of cover, which is common on higher value property.

Here is the important bit. Once monitoring forms part of your fire safety arrangements, keeping it working is a legal duty. Article 17 of the Regulatory Reform (Fire Safety) Order 2005 requires the responsible person to keep fire safety systems in efficient working order and good repair. A monitored alarm that has silently stopped monitoring does not meet that duty, however healthy the panel looks.

What is the PSTN switch-off, and why does it affect fire alarms?

The Public Switched Telephone Network is the old copper phone network that has carried landline calls, and a huge number of alarm signals, for decades. Openreach is retiring it and moving every line to digital services. As Hereford and Worcester Fire and Rescue Service puts it, the network is being permanently switched off by 31 January 2027, and fire alarm signalling systems are first on its list of business systems at risk.

Two things have already happened that many building owners missed:

• BT Redcare has closed. BT’s long running alarm signalling service shut on 15 December 2025. Newer Redcare NGP units were transferred to AddSecure’s platform and kept working. Older Redcare Classic, Secure and GSM products did not. If one of those is still on your wall and nobody replaced it, your alarm may already be off the air.
• Digital phone lines break old diallers. When a site’s landline is migrated to a digital voice service, a traditional analogue dialler plugged into it may stop working reliably, or at all. Some sites have been migrated without anyone telling the fire alarm contractor.

The nasty part is that the failure is silent. The panel lights look normal. The bells still ring on site. The ARC simply hears nothing.

Is my fire alarm affected? A quick check

Walk to your fire alarm panel, or ask your maintenance contractor, and work through this:

What you find	What it probably means	Action
A phone line or RJ11 cable running into the panel or a small box next to it	Analogue PSTN dialler, at risk from January 2027 or sooner	Book a signalling upgrade now
A box labelled BT Redcare Classic, Secure or GSM	Legacy Redcare, which stopped working on 15 December 2025	Treat as urgent. Test the path to the ARC this week
A box labelled Redcare NGP, Essential, Advanced or Ultimate	Transferred to AddSecure, likely still working	Get written confirmation it is live and reaching the ARC
A device with an ethernet cable and a SIM, branded CSL DualCom, AddSecure, WebWayOne or Emizon	Modern IP or dual path signalling	Confirm the grade and that ARC signals are tested at each service
No signalling device at all	The alarm is not monitored	Check your fire risk assessment and insurance to see whether it should be
You do not know, and your contractor cannot tell you	That is the finding	Get a signalling audit before the deadline

What should replace a PSTN fire alarm dialler?

For almost every commercial building, the answer is a dual path signalling device. It sends signals over two independent routes at once, usually your broadband (IP) and the 4G mobile network using a multi network SIM. If one route drops, the other carries on, and the ARC is told that a path has failed.

Signalling option	How it works	Works after 31 Jan 2027?	Typical use
Analogue PSTN dialler	Dials the ARC over a copper phone line	No	Legacy only. Replace
Single path IP	Sends signals over the building’s broadband	Yes, but fails if the router or broadband goes down	Low risk sites where the fire risk assessment and insurer accept it
Single path 4G	Sends signals over the mobile network	Yes, if signal strength is good and the SIM is not 2G only	Sites with no reliable broadband
Dual path IP plus 4G (DP2 or DP3)	Both routes at once, with path failure reported to the ARC	Yes	The standard answer for most offices, retail, industrial and multi let buildings
Dual path DP4	Highest resilience grade with faster polling	Yes	High risk or high value sites such as data centres, pharma and heritage buildings

The grades come from BS EN 50136, the standard for alarm transmission systems. SP means single path, DP means dual path, and the higher the number the more frequently the route is checked. Industry guidance, including this summary from AddSecure, treats DP3 as the usual commercial insurance default and reserves DP4 for high risk sites. Your insurer may specify a grade, so check the policy before you buy.

One extra watch out: some older signalling devices rely on 2G mobile. UK networks have already retired 3G and 2G will not be around forever, so any replacement should use 4G with fallback, not 2G only.

What does BS 5839-1:2025 say about fire alarm signalling?

The latest edition of the fire detection code of practice tightened the expectations on alarm transmission. We cover the wider changes in our BS 5839-1:2025 explained guide, but for monitoring the headlines are:

• Speed. On life safety (Category L) systems, alarm signals should reach the ARC within 90 seconds.
• Fault reporting. Loss of the transmission route should be flagged quickly, within three minutes on Category L systems, and loss of both paths on a dual path system must show as a fault at the panel.
• Testing. Where a system is connected to an ARC, each signal type (fire, fault and so on) should be tested at servicing to prove it actually arrives.
• Grading. The standard does not force a single grade. It sets performance expectations and points to BS EN 50136 for the grading framework.

The Fire Industry Association’s guide to the changes in BS 5839-1:2025 sets out the detail if you want to go deeper. In practice, a modern dual path device commissioned properly meets these expectations comfortably. A 20 year old dialler on a digital line does not.

How do I choose a fire alarm monitoring provider?

You are really choosing two things: the contractor who fits and maintains the signalling, and the ARC that receives it. Ask for these in writing:

• ARC certification. The ARC should be certificated to BS EN 50518 and BS 9518 and operated by an NSI or SSAIB registered company.
• Contractor certification. The company fitting and maintaining your fire alarm should be third party certificated, for example BAFE SP203-1 registered. BAFE certifies fire alarm companies, not ARCs, so a quote promising “BAFE monitoring” is using the wrong words.
• The signalling product and grade. Name, manufacturer and BS EN 50136 grade. If it is lower than what you had before, tell your insurer.
• ARC testing at every service. Ask to see the service record showing each signal type confirmed at the ARC. This is where good fire alarm PPM earns its keep.
• Response plan. Who does the ARC call, in what order, and what happens out of hours? Many fire and rescue services, including in London and Kent, now challenge or filter automatic fire alarm calls from some premises, so your keyholder and 24/7 engineer call out arrangements matter more than ever.
• Clear costs. Hardware, commissioning, the monthly signalling and ARC fee, and any SIM or line rental, all itemised.

Our guide on how to choose a commercial fire alarm maintenance company covers the rest of the vetting process.

What happens if you miss the January 2027 deadline?

Nothing dramatic happens on the day, which is the problem. Your alarm keeps sounding locally, and you find out it was not monitored when a fire happens in an empty building overnight.

The knock on effects are real, though:

• Legal exposure. A monitoring system that no longer monitors is not in efficient working order under Article 17. A change to your signalling arrangements is also a good reason to review your fire risk assessment.
• Insurance. If monitoring is a policy condition and your signal has not been reaching the ARC, expect a very difficult conversation after a loss.
• Engineer availability. Every alarm, lift line, door entry system and telecare unit in the country is chasing the same deadline. Leave it to December and you will be joining a long queue.

A simple 5 step plan for facilities managers

1. List every site in your portfolio with a monitored fire alarm, and note who maintains it.
2. Identify the signalling device at each site using the table above, or ask your contractor for a written schedule.
3. Prioritise sleeping risk buildings, empty out of hours buildings, and anything on legacy Redcare or a PSTN dialler.
4. Upgrade and commission dual path signalling, and have the ARC confirm receipt of each signal type.
5. Update the paperwork. Log the change, review the fire risk assessment, and tell your insurer the new signalling grade.

If you manage multiple sites across the South East, it is worth doing this as one batch. A single survey visit can usually cover the signalling audit alongside routine servicing.

Get your fire alarm signalling checked before the switch-off

Elmstone Fire is a BAFE registered fire alarm company based in Gillingham, looking after commercial buildings across Kent, Medway, London and the South East. We will check exactly how your fire alarm talks to the outside world, tell you in plain English whether it will survive January 2027, and upgrade it if it will not.

• Signalling audits carried out as part of your commercial fire alarm maintenance visit.
• Dual path signalling upgrades and panel replacements through our fire alarm projects and installation team.
• ARC signal testing at every service, recorded in your logbook.
• Rapid response through our 24/7 emergency call outs if a signalling fault or panel fault appears.

Call 01634 395 615 or book a free fire alarm signalling check. Tell us how many sites you have and we will come back with a clear plan and a straight price.

Frequently asked questions

When is the PSTN switch-off?

The UK’s analogue phone network is being switched off by 31 January 2027. Any fire alarm still signalling over a copper phone line needs upgrading to IP, 4G or dual path signalling before then.

Will my fire alarm stop working when the PSTN is switched off?

The alarm will still detect fire and sound on site. What stops is the signal to the Alarm Receiving Centre, so the fire service and keyholders will not be alerted automatically.

What is an Alarm Receiving Centre?

An ARC is a 24/7 staffed monitoring station that receives fire and fault signals from your panel and calls the fire and rescue service, keyholders or engineers according to an agreed plan. It should be certificated to BS EN 50518 and BS 9518.

What is dual path fire alarm signalling?

Dual path signalling sends alarm signals over two independent routes, normally broadband (IP) and the 4G mobile network. If one route fails, the other carries the signal and the ARC is told a path is down.

Is fire alarm monitoring a legal requirement?

Not automatically. Your fire risk assessment and insurer decide whether you need it. But if monitoring is part of your fire safety arrangements, Article 17 of the Regulatory Reform (Fire Safety) Order 2005 requires you to keep it working.

What happened to BT Redcare?

BT Redcare closed on 15 December 2025. Newer NGP units moved to AddSecure’s platform and kept working. Older Classic, Secure and GSM units stopped and needed replacing.

What signalling grade does my building need?

BS 5839-1:2025 does not set one grade for everyone. DP3 dual path is the usual commercial default, with DP4 for high risk sites. Your fire risk assessment and insurer should confirm the grade.

How often should fire alarm monitoring be tested?

Every signal type should be tested through to the ARC at each routine service, which is at least every six months under BS 5839-1. Ask your contractor to show you the record.