Simlock - security software in cell phones set up by the manufacturer to request the operator, usually causing no authorization SIM cards from other operators.
The mobile phone with Simlock can install a SIM card only one operator. The phone can also be locked so that they only work with one SIM card or selected example of cards from a particular country.
Locked phones are usually asking for an unlock code when switched on with a non accepted sim card. Some of them also will just not accept the sim card and show "Not supported sim card" message on the screen.
If you want to use your locked Phone with other than original sim card you need to unlock it. You can do it on our website withour leaving home. Just enter your IMEI in the field on main site and click "Check" - after that click "Unlock This Phone".