The RAS software is I believe a re-badge of the Honeywell system. It might be worth talking to Siemens Building Services (or whatever their name is nowadays) – when I was having difficulties with my (now retired) telscan system and getting nowhere with Poole I contacted them directly and they were very helpful indeed.
Interestingly they seem to still be offering the AX4 Lite
The cameras are just Pelco dome cameras and work with most NVR’s. I found the Hikvision NVR fairly reasonable and the mobile app very easy to use as well.
I have some of the original telscan drives and an AX4 Lite, plus three redundant cameras as well kicking around. If you want/need spares? Theyre about to go in the skip.