There are a wide range of choices available, from bells-only systems to the more sophisticated range of monitored systems.
Bells-Only (Audible) Alarms
This is generally the most basic option, which is unlikely to be acceptable to an insurer if you are protecting commercial premises. In simple terms, if the alarm is triggered, an audible alarm sounds to alert you - or a neighbour - that an intruder has entered (or is trying to enter) the premises.
Speech Dialler or Auto (GSM) Dialler System
With a speech dialler - when the alarm is activated - pre-programmed numbers of your choice will be dialled and a pre-recorded message alerts the keyholder or the person in the business responsible for responding to the alarm.
However, if the phone line is cut or disabled no signal can be sent.
It can typically send a text to up to three numbers, there is no third-party monitoring and can use any major high-street SIM on a network of your choice (for example O2, EE, Vodafone and so on.)
The system installed may be the same as (or similar to) a bells-only system, except that - when the alarm is activated - a signal informs a remote monitoring centre. They may confirm that the alarm is not false and, if necessary, they inform the Police.
Monitored systems do not guarantee a Police response.
Digital Communications (Digicom)
With this system, alarm signals from the system are monitored by an Alarm Receving Centre (ARC), but a failure of the line - such as the line being cut - will prevent an alarm signal being received at the ARC. Typically, with this system, the line is checked once a day - grade dependent - by a 'test signal' being sent to the ARC, where a user is notified if it's not received.
Monitored Signalling Systems
These are systems that monitor the “signal path” between the protected premises and the alarm receiving centre that monitors the alarm system.
In the event of the signalling path, usually a telephone line, being interrupted - usually the cutting of the telephone cable, in the case of a burglary at or near the protected premises - an alarm is activated at the alarm receiving centre and either the Police or the key holder of the premises is informed. The Police can only be informed if the alarm can be “confirmed.”
Dual-Path Signalling Systems
There are several types of dual-path systems, but only some include a digital communicator combined with a GSM system (using mobile phone technology.)
Under normal circumstances, alarm signals are sent to the alarm receiving centre by the digital communicator. However, if this is not possible - eg due to the cable having been cut - the signals are sent by the GSM system.
Other systems use a monitored signalling system, which are also combined with a GSM system. In the event of the monitored signalling system being unable to send an alarm signal to its monitoring centre, the signal is sent by the GSM system.
Dual-path signalling systems have a great benefit, in that they allow an alarm condition followed by a signalling path fault - or vice versa - to be treated as a “confirmed alarm" and, therefore, obtain a Police response. Similarly, faults in both signalling paths can be treated as "confirmed alarms" and obtain a Police response.
IP (Internet Protocol) Signalling
Systems use IP signalling to connect to an alarm receiving centre, via the public Internet - using the ISP of your choice. The system is dependent upon the in-house network setup, but may provide alternative signal pathways to ensure signal continuity.