Locking and Unlocking

I often see the phase "Locking Phone" and Unlocking Phone" in most of the mobile forum, but till today I got no clue at all what that is? Is the locking and unlocking stuff available in Asian country such as Malaysia? ThankS! __________________ If a phone is locked it means it cannot be used with any simcard except the one t is locked to __________________ So what's the purpose of locking a phone? In order to use we have to unlock it? __________________ if you buy a mobile phone, you can buy it with a contract of a mobile operator, with a plan or pre-paid version... so the phone gets cheaper, but you are stuck to that operator. It's just that the operator is sure that the phone can't be used with an other operator. + cheap phones - no other networks alowed and you have a bad plan (contract mostly) to unlock it you just have to press a code... published here before several times... __________________ just find DCT 4 unlocking codes very easy to find