Thanks these are all great solutions! I'll try the things you suggest.
Thanks a lot!!!
(The guy I mentioned this to and who works in IT lives in Israel. Maybe they have a more modern system over there, I don't know! He did seems surprized that the telephone line was involved)
@tuitui22 This type of problem wouldn't affect a full fibre optic line so that's where the misunderstanding may have originated? If you could do the test socket check and also do the quiet line check and post back the results it will help us understand if the problem is on the network/line or within your home set up.