http://www.clifford.co.uk/Support/Guides.aspx

this should help you. I have a Clifford Avant Guard 5.1 and it can do so many thing and be customised a hell of a lot, so you could have done any number of things. you can make it so it doesn't beep when arming and de-arming. Best off find out which alarm it is, I'm guessing one of the Concept alarms. Download the manual from the site above, and have a good read through. you iwll need to know the access code to enter the setting to change things though. hope this helps.