if the broadband is working on the line currently, and voice rental is via BT, then it is not a full LLU solution, and thus a MAC is available, and you may have always been on shared LLU.

NOT ALL line rental and broadband lines from Sky are full LLU, they are using a mixture.

There is no broadband on my line at the moment. No adsl light on the router.
As my phone number is still not showing on the BT line checker I will continue to use mobile broadband.

Happy days. After five weeks my telephone number has finally appeared on the BT database with the correct information. I can now go ahead and order broadband but not from BT. as their customer service was pretty grim.