Your right! I read this a while back but not the full article. He claims Jeremy moved the phone from his parents room and plugged it in downstairs in order to prevent them calling 999, then further down the article he mentions disabling all lines with the phone off the hook, then why argue Jeremy unplugged the phone upstairs when he could have used the phone already downstairs to disable the lines? Strange.
I don't think your reading the article correctly,
The first thing he did on entering the house was to take the kitchen phone off the hook. By doing this he disabled every phone in the house.
But he did have a major problem. What if investigators asked why Nevill or June hadn’t dialled 999 from the bedroom? And why was Nevill’s body in the kitchen? Bamber had to improvise. So he plugged the ivory bedroom phone into the kitchen socket — hastily hiding the kitchen phone under magazines.
He had the problem with Neville being downstairs