Everything Apple (the Mac heads thread)

My iphone 3 has just broken after 4 years of service, and apparently O2 'don't do loyalty' and I dont want to change my contract or sign a 24 month one so...If i buy a second hand iphone 3gs, and get it unlocked, when I go to restore it from my backup on my computer in order to get all my photos, number etc put on it, will it lock the phone back on to the original network, or does this not affect the lock of the phone?

Hope you're not still paying £35 a mont for whatever the original contract was... iPhone contracts were never that great. I went down to £20 a month once my contract wwas out and it's a rolling contract so I can cancel anytime...