With the Smart Phone Era; this post may seem like a far cry; but still could be a relief to some who are happy with their simple Nokia Handsets
In certain countries; the Phones you purchase from Authorized dealers could be locked for use with SIM Cards of Service Providers in other countries. This could land you in a soup when travelling and have to use a local SIM on your existing phone. This is when you may need to unlock the phone to have the restriction removed.
The below website is an excellent guide to help you through. But sadly there is no guarantee; that your Nokia can be unlocked with their instructions. Try your luck.