Ther is one major test you can do if you are sure your own home phone is not at fault. You can check its function at a neighbours fault free socket. Once you are are assured of this and have a modern master socket, unscrew the two screws, this will release the bottom section of the master phone socket. Plug your phone into the socket behind this and dial 17070, select option 2 and put your phone on mute. If you hear any noise at all this indicates a fault on the line and will need to be attended to by the line provider, Plusnet, who will then raise a problem with openreach. Hopefully someone from PN will be in touch soon.