My post read that if you find an old Nokia that has been on Vodafone i can gaurantee most will be unlocked you dont need a vodafone sim card in it, I have a nokia 7610 quite new which is unlocked to all networks whenever I am away i just buy a cheap sim card and log on to whatever network i can find, not all other phones that were on Vodafone are unlocked though and you need to take them to someone who can unlock it for you.
A quick test would be to take your sim card out and replace it with a different network sim, say orange or O2 if the phone works on there it is unlocked
Ron ( Phone unlocker )