As far as free ISPs go, I've found "ntl world" excellent. A genuine 24hrs/day 0800 dial up, which works well with no hang ups etc. Terms & Conditions ? Of course!
Basically you must spend £15/month on (non-internet) phone calls from at least one of your two registered landlines - certainly not difficult in this household! You do NOT need to be on cable to use the service - just a BT line and either use a (free) ntl box or dial 1263 before making a call - works well here in a remote part of Scotland where even BBC2 is quite advanced!
Phone calls are cheap too and SIMPLE compared to BT. 3p/min peak, 2p/min offpeak, 1p/min weekends whether the call is local or national.
Anyway enough of free advertising for ntl, except they are very good (and free) to use.