I’ve had this problem on and off for some time now. I have 2 cordless phones and the fault shows on both of them. Last week a VM engineer spent some time here, checked the box outside our house and the main box across the road. He adjusted some wires on our box - his report says “reconnected in omni wire was pulled very tight”. When he tried to replicate the fault using his equipment plugged into our socket there was no crackling but it still is on our phones. I could understand it if it was on one phone only but it’s on both of them. So we’re back to square one and barely able to hear anyone on the line which gets progressively worse as the call goes on.