The C902 is a camera phone by Sony Ericsson.
If you purchased your C902 with a cellular plan, it would be
locked to your company's network and can only be used with that network.
If you want to switch networks and continue to use your
C902, you have to get it unlocked from the current network.
The simplest way to unlock your C902 is through remote IMEI
1.Obtain the unlocking code for Sony Ericsson C902 from your network's support
You can call them up and talk to a customer support
Request the unlock code and give them the phone's IMEI number.
As an alternative, you can purchase the unlock code from the
websites such as Unlocking,
FonesZone or UnlockItNow.
You will need to provide the IMEI number on the websites.
Close all applications to reach the standby screen of the
Press the left direction key on the navigation pad.
Press the * (asterisks) key twice.
Press the left directional key once again. You will see a
menu titled "Personalize."
Select "Network" in the menu. Select
"MNC2" in the second menu that appears.
Enter the unlock code you obtained in Step 1 and select
"OK." This will unlock the phone.