It does not matter whether your phone number is 427, 449, or 484. These all come from the exchange of Hollins lane.
BT Openreach installed the fibre to new cabinets some months ago. That is as close as the fibre will get to your house.
Copper cables were then installed to link these new cabinets to the existing cabinets, thereby connecting the broadband service to your existing telephone line at a point closer to your house. As the 'Broadband' connection is now shorter it is able to be used at a higher data rate (higher speed).
I suspect that if your house is not connected to one of these new cabinet then you will not be able to get BT Infinity. This may be the case for houses away from main roads.
Ps.
I do not have any inside knowledge about BT Openreach, I just spent the last 20 years working on computer networks. !