If it is a branded Vodafone handset then it will be locked, however it is possible that it may be a sim free(unlocked) handset, as often pay monthly handsets on Voda are not network locked. Put an o2 sim into the handset and see if it works, if not then it can be unlocked for £10-£15 in any unlocking shop. I would avoid any unlocking codes from the internet as they are often a waste of money and dont work.
