Let me give you a little background and then some solutions. This is generic because I don't know your carrier. I'm using ATT as an example.
Phones are naturally unlocked, but a service provider might lock them
When originally manufactured, all GSM cell phones are unlocked. That is, they can be used with any SIM from any cellphone service provider - always assuming, of course, that the cellphone service provider has compatible GSM service on the same frequency bands that the phone can operate on.
Most cell phone service providers electronically 'lock' the phone so that it can only be used with their service. There are obvious reasons why they choose to do this - in particular, to force you to pay what are usually very high roaming charges when you take your phone out of their network and use it elsewhere in the world.
Fortunately, this locking is reversible. With some phones, it is possible to simply enter an unlocking password code into the phone and it is immediately then unlocked. Other phones need to be connected up to a special unlocking data terminal.
Your phone has to be unlocked by the carrier. LG, Motorola, Sony Ericsson, Nokia and most of their ilk, will not give consumers the unlock codes but don't despair.
A PUK (PIN Unlock Key) code is required to unlock SIM cards that have become locked following three successive incorrect PIN entries. If your SIM card becomes locked, you will need to get a PUK code from your carrier. For example, if you have AT&T to unlock your SIM card, you can obtain your phone's PUK code from AT&T by:
● logging in to your my wireless Account online
● using their Technical Support Chat
● calling Customer Care at 1-800-331-0500
To get your phone's PUK code online from ATT:
● Log in to your my wireless Account.
● Select My Services under My Account.
● From the My Services screen, select My Phone/Device.
● Select Unblock SIM Card.
● The Unblock SIM screen will display your PUK code.
Once you receive your PUK code, you will need to enter it into your phone to set a new PIN code.
Note: If you enter the wrong ATT PUK code 10 times in a row, your SIM card will be invalidated, and you will need to purchase a new SIM Card. The phone will display the following error: "PUK blocked call operator."
There are three other ways to unlock a phone:
● The carrier will unlock the phone for you at one of its retail outlets;
● You can do it yourself by clicking on this link Free Unlock Code
● Pay $3.89 at the following website: www.theunlockshack.com/
I trust that this is helpful and solves your problem. All the best