Cell phone providers "lock" phones to their service. That means that it only works with the provider's service and one of its SIM cards. However, the law requires that the phones be physically "unlockable." If you have the right information, including your IMEI number, your service provider will give you the code to unlock your phone so it can be used with other providers.
Type "*#06#" (star, pound, 06, pound) on your Binatone phone's keypad and press "Send." This will fetch the IMEI number to generate the unlock code. The number will be 15-17 digits.
Call your phone provider and request an unlock code. Give the customer service representative the IMEI code and your phone model, and write down the unlock code.
Open the back of your phone and remove the SIM card--a small rectangle of white plastic. Put in your SIM card from your new phone provider. A screen will appear to enter the unlock code.
Enter the unlock code on your keypad and press "Send." The phone is now ready to use with other providers.