You will not be able to move a Virgin or TalkTalk number to anyone other than BT.
I wasn't aware voipfone.co.uk were part of BT. :-
"We can transfer any BT and Virgin Media (ex NTL & Telewest) number (01, 02, 0800, 0845, 0870, 0871 etc) onto our service."
Keef- Dartford Kent UK - VirginMedia 10M
Previously - Crosswinds, IC24, FreeOnlineNet, X-Stream, Totalise,
Freeserve, Force9, TescoNet, AOL, Freenetname, NTL, Pipex, E7