myself have Eircom phonewatch. It's okay for the most part.
As Mr. Earl says, Phonewatch were sold off years ago, they were bought by Sector who were stuggling to off-load their out of date technology and saw this as a nice little earner.
They will only supply the Sector kit, and have it locked down so no other security provider in the country can work with it, so you will be locked in to them for monitoring unless you go to the trouble of installing another system. Every other installer will supply a system that can be monitored by a number of providers, thus ensuring there is competition to keep prices lower.
Also note that their default designs will only detect an intruder once they are already inside your home, most other providers will quote you for a system that covers all potential entry points and explain that to you without the pushy sales speak.
PhoneWatch also don't employ fitters who are qualified to wire the system into your mains, so instead will install the box near a socket! A security system should be installed on it's own circuit. You don't want a faulty appliance tripping the RCD taking out your alarm system.
So whatever you do, don't get PhoneWatch! Look up licensed
installers in your area and ask a few to quote.