I have 3 phone extensions. When BT converted my main socket and the extensions, I did not have a further extension converted in a bedroom. It still has an ancient round jackplug. I read somewhere that when you have broadband, you must put a filter in every socket even if there is no phone connected. Is this true? I've had broadband for a year but the phone line is not as clear as before broadband and the broadband itself is not totally reliable. I wondered if this might be a contributing factor?
If so, I will need to get this redundant extension unwired from the previous extension which has been converted.