When callers ring our number they are unable to make a connection. Sometimes the phone will ring once and then disconnect

On our side of the pond, this often means there is water in the line somewhere. High dampness coupled with insulation that has degraded can cause low resistance paths. This usually doesn't cause any problem when you place a call, although it can sometimes cause crackling or other noise. But when someone rings your line, a high voltage is sent to operate the ringer. The low resistance then makes the telephone equipment think you've answered, but since your phone is still hung up it then disconnects the call. Sometimes the phone may not even ring, sometimes it gives a little peep or even a whole ring.

This problem may be due to damage to a telephone jack in your home. I've seen it caused by water when someone was cleaning the floor, and also when a jack near a window was soaked during a storm. The trouble may also be in the outside wiring, which should make it the responsibility of BT to repair. It's also possible, although rare, for a dodgy phone to cause this if there's a problem in its ringer circuit.

Hope this gives you some help in locating the cause and fixing it. Thanks for using Fixya!