BT have requested porting the number three times. Twice while I was still a VM customer and once since I have left you.
Due to the timescale involved the number is probably no longer active. My account was officially closed on 06/03. Attempts were made to port the number in December and again on or around 13/02. I requested BT try again last week which they did when I was the phone to them and it has again failed.