Depending on who you chose to provide your phone service, it may well cost you (quite a lot) to get the line working again. Don't assume the service hasn't been ceased just because you've got a dial tone. If it has been ceased, the line needs to be reconnected by a BT engineer somewhere in a junction box/at the exchange. Don't know if BT would charge for this, but Southern Electric phones (Talk) have just charged us £115 for reconnecting the line - we had a dial tone, but no DSL and the BT bloke had to come into our house to finish off the work....

Good luck!