A word of caution ... if your alarm is not monitored, Eircom charge you a premium to come out and change batteries in sensors/control panel etc.
... our battery in the control panel went a few years ago ... even though it is wired to the mains, it uses the battery for back up ... bloody thing kept beeping telling us the battery needed replacing ... as we had stopped the monitoring service, eircom wanted 85 euro to come out to change the battery + cost of battery. Needless to say Mr. HP sourced the battery online and did it himself ... but I just though you should be aware of the additional charge.