mobile phones

[Andie23]

My 12 month contract with 02, arranged through Mobileshop, is coming to an end. With the cashback included it works out at �15 per month. I've seen a offer for 12 months free line rental on a 12 month contract, again with O2, through Phoneboxdirect, for which I can get �15 back through Quidco too. I want to keep my existing phone number. I'm assuming that I switch in this way? Can anyone give me guidance on the mechanics of how to go about switching please and the order I do things � (ordering, Pac codes, cancelling exisitng contract etc). Many thanks