no dial tone sounds like a problem, even though you can make calls. so just to clarify, this is an old style viring phone socket (similar to a BT socket), that is fed from a separate cable (and not just an extension from the hub).
have you checked there aren't any loose wiries at the socket?
Just had Virgin engineer here. Nothing wrong with line despite lack of dialling tone. The problem is ADSL to PSTN - phone line is the former, FAX is the latter. Ideally, the FAX would have this as a choice in settings, but the only choice is between PSTN and PBX so I will need some kind of filter. I might reply again if I can get hold of the correct filter and attach a photo, just in case anyone else has the same problem.