hi you can get the network unlock codes from here onlinegsmunlock here they ask the following details before rendering the codes they are
1. Mobile model
2. Country from where you brought the mobile
3. Provider to which the mobile is locked
4. Imei number of the mobile
Finally they will send you the unlock codes .once
you entered the code in your mobile as for the instruction
given by them .your mobile get unlocked and it accepts any network sim.