Old laptop

I have a problem with my phone system,  a BT Versatility (left over from when I had my own business, but now retired). I need to re-program it to get rid of the non-existant lines, and it uses a serial port to do so. The only capability I have is an old laptop that is running Vista. I did find it has V10 TV installed but when I tried to upload the latest version (my PC is new and running 15.6.7 on Ubuntu) I was unable to do so. Which version do I need to download to the laptop to operate it remotely ? The phone system is in a small cupboard so operating the laptop locally would be a real pain, if not impossible due to the short connecting cable.