Hi el0w,
What's your current network provider?
I guess you mobile locked to any one of the GSM network provider.Unlocked GSM mobile phone only work in GSM network.So you can't use CDMA network provider
verizon is CDMA.After unlocking you can't use Verizon sim card in your mobile phone.But you will be able to use any GSM sim card in your mobile phone.
You can unlock your locked mobile phone using an unlock code.It's the best way to unlock your mobile phone.You can get an unlock code from your service provider or else try to buy an unlock code from online unlocking service provider.If you need an unlock code visit Simpleunlocking.com and you can get free unlock instructions from Mobileunlockguide.com It's very useful do your unlocking.