I hear you but where do you draw the line? It has to be presented to a jury in such a way that they can make a decision based on what the evidence suggests. The fact a phone had the handset off the hook means his statement that myster posted via soundcloud about the phone being engaged immediately means that it’s a lie anyway. It would have been an open line so regardless of when this phantom call was made it was proven to be a lie. He didn’t think it through properly. In additional to this handset evidence, the coincidence of the phone being moved from bedside to kitchen under magazines is another piece of circumstantial evidence that points to it being even less likely that NB made a call even before or after.
Like I said, I agree with you. The phone call was one of the first things that made me suspicious of Bamber's innocence. Nevill never called Bamber that night.
I think Bamber left the phone off the hook in order that if rang, the caller would get the engaged tone, that way they would think Nevill was using the phone - hence - still alive. Unfortunately, he didn't know enough about the tones and tied himself in a knot with how the alleged call ended with Nevill.
Just to clear up someone points about the phones - the dial phone was from the bedroom. Bamber argued that the push button found in the rack was a 'spare' but I believe it was the kitchen phone.