Recently anyone phoning our landline has said they can’t hear properly due to terrible interference and crackling noise. I can hear them clearly. I even bought new phones but this is even worse, they all say the noise is much worse and it’s even a bt phone. Don’t want to be charged for an engineer as so far after doing all recommended checks by are saying there’s no fault on the line. Why can’t anyone phoning me not hear me then and where is the crackling coming from?
It could be an exchange fault.
You really need to see if the problem occurs if you leave the phone plugged into the test socket.