The line was open because it was left off the hook, doesn’t mean it was connected anywhere, Bamber clearly states he tried to ring back 20/30 seconds later he has a memory dial which he normally uses when he tries to ring a number that’s engaged. He would not have been able to make a call unless he cleared his own line first and if he didn’t clear his line each time he picked the phone up he would still be connected and then that would take another two minutes to clear again.
You don't know whether the line was open because it was off the hook or because NB made a call to JB and abondoned it. The soc evidence supports the latter because it can be evidenced that the totality of the physical evidence documented and photographed by way of blood stains to flooring/lack of, casings, distance of shots, trajectories and wound tracks show that the perp was in the main bedroom shooting June with NB then arriving on the little staircase just before the entrance to the main bedroom where he sustained his facial wounds.
The expert evidence from trial:
68. There was no evidence of telephone billing information of the sort which would be available these days. There was, however, expert evidence called as to the effect of a telephone call having been made from White House Farm to Goldhanger which was then abandoned by the caller with the receiver being left off the cradle, as claimed by the appellant. If such a sequence had occurred, the telephone link would have remained open either until the handset at White House Farm was replaced or until the handset at Goldhanger had been replaced and left in position for a period which could vary from 1 to 2 minutes, when an automatic interruption of the link would take place. Until one or other of these events, the appellant would have been unable to make any call from the Goldhanger telephone.According to the above JB would need to leave the handset at GH on its caradle for at least 60 seconds until he was able to make a call eg JM, EP.
