When we renovated our house over 15 years ago, we put in some automation systems. The brain was a
Comfort system from Cytech. This is fundamentally an alarm system that does a few other things such as offering a voicemail system and has expansions for IR blasters and the like. It's accessible via a serial interface and programmable via 'comfigurtor' software. Connected to the comfort system are a set of window and door contacts, a doorphone, keypads and some PIRs.
Also installed were a number of hard wired X10 controllers (LD11 din-rail dimmers) which were set to control various lights via wireless switches and could be addressed via the comfort system (when coming home and entering the system disarm code, switch on the lights if it's after dark etc.)
In recent times, the X10 systems have been gradually degrading. Lights would switch on by themselves or fail to operate on command. It was time to start looking for options.