hi,
i know about this...if u can try below like that...
To unlock your sony ericsson w580i phone you will need to enter combination of numbers. These numbers are just math calculation of IMEI number of your phone. To find your phones IMEI number, look under the battery for it - it is 15 digits.
There are different online services that will generated the unlock code for your IMEI number for just about 20$. I can recommend this one (cheap and reliable).
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rocke