I called BT, they told me their price (79 pounds a line for install, 14/month line rental, doubtless all plus VAT).
NTL, once we'd figured out what area I was in (I remember this problem from trying to get stuff from them as a residential account; we're very close to the boundary between two of their areas and it's not obvious to the casual observer which one we fall into), very politely told me to go to BT; though their installation and rental is slightly cheaper, they have a £250/month minimum call spend.
Yow.
Well, guess it'll be BT then, it makes my decision easier...
