When does a mobile phone get 'locked'?

Question

What does it mean to get 'locked'?

Does it happen when u take a USA mobile phone to Asia(I think the GSM frequencies used in the two regions are different)?

Or when u switch between serice providers?

Also when it is locked what is displayed on the screen? Basically how do u know the phone is locked?

Answer 1

Locked means that it has been set up to only work with one carrier, that is the company that originally purchased the phone from the manufacturer. IE: AT&T wants to offer I-Phones but doesn't want people removing the sim and using another carriers sim in their phone. They in advance have the manufacturer of the phone or they themselves before selling the phone, enter code to the phone to "Lock" it to themselves for service. Unlocking is removing the code so that you can use it with any sim on another provider.

You wouldn't neccessarily know a phone is locked unless you tried another carriers sim and it will tell you the sim is not a valid sim for the phone.

Answer 2

i dont know any of the begining stuff, but it shouldnt lock, for it only locks if you hold down the (lock) key, or if you go into phone options... on most carriers, it will say (phone locked) at the topof the screen. it will basically be the same as usual, but you cant go anywhere without unlocking it, and it will be the same background, but no banner, if you have one set. the default unlock key on most carriers is the last 4 digits of your phone number