Monitoring connects your panel to somebody who is awake. What happens next depends entirely on the contract, and the gap between what buyers assume and what they have bought is wide: most monitoring produces a phone call to a keyholder, not a fire engine. Knowing which you have is the whole value of the arrangement.
What monitoring is
A transmission path from the panel to an alarm receiving centre, which watches for alarm and fault signals around the clock and acts on an agreed response plan. The path is normally a network connection with a second path for resilience, and the centre monitors the path itself, so a cut line is an event rather than a silence.
What happens when a signal arrives
That is the response plan, and it is negotiable. Common arrangements are calling named keyholders in order, calling the site first to check, or passing to the fire and rescue service under an agreed protocol. Fire service response to automatic signals is managed locally and many services will not attend an unconfirmed automatic alarm at commercial premises, so this is a question for your own brigade rather than a national answer.
Who actually needs it
Buildings that are empty for long periods, buildings with sleeping occupants and no waking staff, and buildings where a property insurer requires it. In a workplace occupied only during the day, with people present whenever it is in use, monitoring adds least. Where it is an insurance condition, the policy will specify the standard of the centre and the response, and that specification is the thing to buy against.
Relays, interfaces and remote indicators
The physical connection is usually a relay or an interface module on the panel that changes state on alarm and on fault. Beside it you often find remote indicator units, small lamps outside rooms that show which detector in that room has operated, so somebody searching a corridor of closed doors does not have to open every one. Both are small items that make a real system usable, and both need testing.
Questions people ask about fire alarm monitoring system
Does monitoring mean the fire service will attend?
Not automatically. Many fire and rescue services do not attend unconfirmed automatic alarms at commercial premises. Ask your alarm receiving centre and your local service what the agreed response actually is.
Is fire alarm monitoring a legal requirement?
No. It becomes a requirement through a fire risk assessment that relies on it, through an insurance condition, or through a licence. Where it is relied on in the assessment, it has to work and be tested.
What happens if the connection fails?
The receiving centre should see the path fail and act on it, because the path is monitored as well as the alarm. A monitoring arrangement that only reacts to alarms cannot tell you it has stopped listening.