I have to say I'm little surprised there are people with land lines still...
I think we might have problems with things like with making telephone calls if we didn't have a telephone line.
Regarding the BBS, I think it should have nothing to do with the internet at all. I am all for using a modem to connect directly to it (provided that my mum doesn't mind - she is very against me using the telephone line for computers because we have ADSL).
If it will be in the UK I am quite happy to use either a local or national number, but 0800 or 0845 would be better. Maybe it could just use the BBS owner's own telephone number to start with and then move onto 0800 numbers later.