I'm trying to establish what this number provides, how do I trace what service my number provides.
are you a BT Retail customer paying BT for broadband or just phone
Plugging a phone in and calling 150 will normally connect you to your service provider (in most cases) or if you call the number if you have voicemail it will likely tell you who provides the number failing that check your bank for payments going to someone
I don't understand the question. You are a BT phone customer, what is it you want to know?