Alarm systems have warning devices and more often than not an external sounder to supplement any signalling
The intruder alarm will be fitted with an internal sounder which doubles up as an entry exit low tone sounder and a high
pitch sound when in alarm condition
The external sounder will have tamper devices and its own back up battery so if it is removed from its fixing it will activate
the alarm system and even if the wiring is severed the sounder will continue to operate on its own back up supply.