I suspect both
At the original broadband conversion there must be some hardware update in your local exchange.
Once you sign on, I think the whole range is there, but you are filtered or limited to the speed that you have paid for.
I ordered "Gold" from Aol and a box of bits arrived labelled "Silver". I told them about this, and without realising at the time I was in to a 1 year contract for "gold." It didn't matter but it was a soft conversion, and "deadly swift and silent."