When you purchase a mobile phone, either on pay-as-you-go or a contract, the network carrier includes a SIM, a chip in your handset, containing a serial number that identifies you to the network provider. Unlocking enables you to cut all ties to your initial mobile network provider without replacing your mobile phone. The only reason to lock the SIM is to ensure you use their service for an extended period of time. If you attempt to use an alternative SIM card in a locked phone, you will receive error messages, such as "SIM Card Not Accepted". Unlocking enables you to use any SIM card on any network in your handset. Most network carrier "lock" your phone so it works only with their specific SIM card, a chip in your handset, containing a serial number that identifies you to the network provider.
What we will do is erase the phone's IMEI to unlock the network and thus allow our terminal
signal caught any other operator.
They also explain how to restore IMEI, because in some countries it is a crime not having IMEI
To clear the IMEI use the SmartFlash Tool. You must backup for your photos, and applications because it will erase everythings.
More details of the instructions here.
Once process is complete turn on our terminal and check that it has been cleared by inserting a SIM from another company or if we look defaced IMEI by dialing *#06# ... if yes, WE HAVE OUR PHONE RELEASED!
Now we have to restore the IMEI
Now we proceed to restore IMEI. We need to know the IMEI is having our phone, so you can look at the back of the mobile phone or on the invoice.
Now write the following:
Once process is done introduce introduce 3845#*970# on the dialer and changed CP USB -> USB AP and ready.
Reboot the phone and check the IMEI by dialing *#06#.