I can only advise as a company that has used these systems for over 12 years and the most popular system at the moment is the IA 230 but if it were for a domestic installation I would personally say the HSA6410 because this is the cheapest full system which incorporates the auto dialler, but it does have slight advantages at it’s the cheaper price tag. The main disadvantage is it only has a 30 m range but if this is a domestic installation that is not an issue AD Alarms as never had a problem with the 30 m range it will connect to any devices in the building and even external buildings like a garage or shed within reason without any problem whatsoever. It works at the lower frequency 44 MHz not 88 MHz hence the shorter range. but if you’re wanting to save the extra expense I wouldn’t be bamboozled by thinking the 200m range is needed for a normal size house or flat.