phone help

[tiggerbounce77]

I have just sold my mobile on ebay and he wants to know if it works on 3 network, when I got it I was told it was unlocked, I am having trouble getting a 3 sim to try, if and o2 or vodafone sim work would that mean it wo7ld work on 3 network?

 

[tinks77]

If an O2 and vodaphone sim work then it's usually unlocked