1. - Turn on the handset on with a SIM card not accepted by the device (your new network operator)
2. - If the card has a PIN number, enter it and press OK.
3. - The device will prompt: “Network lock”, Now enter the code and press OK.
4. - Your phone will indicate: "The operation was successful", becoming permanently unlocked.
Minor code: If the code in step 3 does not work, type the code [CODE2] and press Unlock, the phone will indicate Unlock fail, now dial the code again from step 3.
For T-Mobile devices, follow this steps:
1. - Make sure you have an active data connection via 3G/4G/LTE or Wi-Fi.
2.- From the Application list, tap Device Unlock, the application is located in the T-Mobile folder.
3.- Choose the Permanent Unlock.
4.- Restart the device.