I have a Sony Ericsson W580i, need help with three sim card?

I have a sony ericsson W580I and I also have a Three sim card. What I want to do is use the three sim card in this phone. The phone seems to be unlocked as I have tried it with vodafone and O2 sim cars but the Three network sim keeps saying " please select a network" and there are only two (O2 and Vodafone).

Please help Quickly thanks :)

Since it is able to recognize other networks, i am sure it is unlocked. Because locked phones doesnt accept other networks. I suffered with one such phone and was relieved once I got it permanently unlocked through unBBlock.com. I doubt there is a problem with your 3 sim card.