For some Caller ID FAQs try here:
http://www.ainslie.org.uk/callerid/cli_faq.htm
Although I moved back to BT mainly because they offered Caller ID, I'm afraid I wouldn't encourage NTL to invest heavily in the equipment to provide it. This is because the rest of the world is swiftly moving towards VoIP (Voice over Internet Protocol) - and with good reason. To provide broadband needs only a couple of racks of equipment but the equivalent telecoms switch requires a whole room full. I predict we'll see STBs with a phone socket on the back before too long - complete with CallerID and every other gizmo.