If your Nokia shows the error
message "Invalid Sim" or "Sim not valid" the your phone is locked to a
particular network. To fix this problem you need to unlock it. Use
unlock code to unlock your . To get the code you have to
submit network provider, country and IMEI number of the mobile. Make
sure yourself whether you have knew the network provider to which your
mobile is locked, country to which the locked network belongs to and
IMEI number of your mobile. If not you can find the IMEI number in two
1)Go to Options>status
2)Find IMEI on the back of your mobile, behind the battery.
3)Type *#06# and press call button. It will display your IMEI number.
can find the network provider to which your mobile is currently locked
by switch off your mobile and switch on it again. A logo of the locked
network will get displayed on your mobile screen. After knew all these
get the code from the site Mobileunlocksolutions.com
these to them. Unlock it yourself using unlocking instructions which is
given in the site itself.