Do you need a PlusNet line to have Fibre ?

[#1]

Looking to recommend a few of my colleagues change to Plusnet Fibre.....
Lines are currently with BT for Voice, and Demon for rubbish ADSL.....
My guess is they want to remain with BT, so could they switch to PlusNet Fibre only, and not have a PlusNet line ?

[#2]

Yes but there is a £50 installation charge https://portal.plus.net/fibre-broadband/broadband/

[#3]

setup fee's not an issue, just knowing u can get the service without having to take the line....
I already got Fibre and a different Voice carrier, but i signed up last year.....
Just wanted to double check u can get Fibre without the tele service...