I used to pay for Caller Display, but a few years ago BT introduced "BT Privacy At Home", which is free, and includes Caller Display. It's still available - details
here
Maybe Jugglering, sandmaster and mandimoo have done this in the past, and don't realise they have Caller Display because it's free and does not appear on the bill. One way or another, their line must be enabled for the service - the phone can't do it on its own without the data burst before the ringing starts.
It appears you're right about 1280 rainbow2 - see
this.