Mike J - There are no known problems with my modem and, with my brief flick through Troubleshooter, everything is set correctly.
BOAC - When I spoke to Freeserve, they said the number my modem was trying to dial was correct.
Mazzy - I don't have Phone Dialler installed, and it's not an option on my Windows components.
I'm an eejit & completely forgot to find a new Freeserve CD at lunchtime.