FTTP - do I still need my BT line?

[#1]

I have been on the Milton Keynes FTTP trial for some time now, and recently (after I suffered a BT landline fault which left me without a home phone line for 3 days) I had considered ditching my BT home phone contract and just using my mobile for calls. However, do I still need to maintain my BT line for FTTP to work? It was fine whilst my landline was not working for 3 days, so I suspect (technially) I do not - but it there something in the PlusNet contract that I need to have this?
Thanks
Andy

[#2]

I second this, having survived  without a BT line account, using my mobile and BB Dongle for quite a while since moving house, before getting Internet BB.
Why do we need a BT line account  if we are provided with  Fibre in any shape or form, apart from the physical length of wire between the cabinet and home ?
Other than that it is a source of income for the provider ?
I rarely use my landline for any calls, in or out, after line rental, my average monthly cost is £nil.

BT used to offer a light user discount, is this something PN could consider ?
As, for example, Primus do.

I am not in a Virgin cabled area.
I am extremely pleased with my PlusNet BB and CS, and have no intention of moving elsewhere.

[#3]

You have to have a phone line provided by BT Wholesale, but you can chose any retailer you like (BT, Plusnet and the Post Office and plenty of others).

[#4]

Technically, I wouldn't imagine you would have to. The POTS network works on voltage and therefore copper whereas FTTP works purely on FO which would use VoIP for making telephone calls.
Although Virgin for instance use coax from the cab, you do not have to take their phone line rental with their broadband even though the coax cable has coax with 3 x twisted pair for POTS with it.
As for BT, I'm unsure who lays the FTTP to the actual premise and whether or not they would want a return on that via line rental. If they do, then it's certainly a revenue making reason as technically you don't need the copper with the fiber.
Just because you cut the copper off, shouldn't mean the fiber should be as well. I would iamgine they would change their wording to "connection to the property" or something similar which would encompass both forms of media for rental purposes in their agreements.