The problem is I cannnot make phone calls except by using pulse dialing. This problem arose some time between 23 and 26 December. I have tried two different phones, and the master socket (but not the test socket, as I am moving house soon and have packed up my screwdrivers). When trying tone dialing, the dial tone cannot be interrupted.
I called Plusnet, but a line test did not reveal any problems. Broadband appears unaffected.
I don't want to leave a problem for the buyer of my property. What could be happening?