How to unlock phone to change network?

What is the code to unlock a samsung j700 phone to change network from virgin mobile to put in an 02 sim card??How to unlock phone to change network?
You can take it to the store or call them, though you'll have to pay. However if you lie and tell them you need to use it overseas they'll give you a code to type into the phone and you can unlock it free of charge!How to unlock phone to change network?
Hi what you need to do is take the phone to a local market stall that unlocks phones ! it should only cost around 拢10 to do then it will be open to all uk networks except ';3'; when you've unlocked it what you need to do then is get the settings from o2 for mms %26amp; the internet so that you can still send %26amp; recieive picture messages you can get the settings either by going on to the o2 website %26amp; downloading them or going into your local o2 store .... hope this has been of some help to you
To unlock your phone, you must buy an unlock code (each phone has a different unlock code). you can get one for your phone on this website http://www.unlock-phone-samsung.com
take it to any phone store and they will unlock it for you.