See reply I added to similar post on Guard Tec alarm, it's exactly the same for your alarm.
alarman, July 2009
Hi Brian, its easy to do, if you do it the right way, give me a ring and I will the way to do it.
It will only cost you a phone call, but Please only ring between 6pm & 9pm Only.
Joe, Alarm Engineer, Skegness, Tel 07525922917, July 2009