This may not be 100% legal, but this site claims to generate an unlock code for your Nokia phone for free. You just need to provide your IMEI code, which they swear not to save, and your country, operator and phone model. The standard disclaimer:

The user is hereby advised that codes generated at www.lur.nu can cause damage to the cellular phone.

This site (www.lur.nu) does not take any responsibility for damage caused by unlock codes. The user of the codes is responsible for any legal documents between the user and the operator.
www.lur.nu does not answer to any questions how to use the codes, or free unlocking whatsoever.

We'd recommend trying it on an old phone before using it on the one your work gave you. – Jason Chen

Unlock codes for Nokia GSM Free [lur.nu via Red Ferret]

Send an email to Jason Chen, the author of this post, at .