Most 56K dial up ISPs already have a time cap in place and have for a long time. Only NTL and AOL that allowed constant redialing with no time limits.
Most ISPs had to change the way they allowed this service byt he few that used it heavy and was stopping others connecting. The main thing is they are looking. I would say if your exchange is enabled for ADSL then go with it if you are moving from NTL as the others work out dearer.
There is an article written by the Admin of our forum. I will post a link if Neil doesn't mind it explains
Expectations - Unmetered Usage this was written when our forums flared over the ISPs limiting the time online per month. Hope it helps on the understanding why its hard to get online when these ISPs are working to their correct capacity.
Neil if its not acceptable please remove the link and I will gather the important parts and paste them in..