Changing Security Code for free
I know that this post is a little late, but maybe it will help others in the future. I too ran in to a similar problem with the security code. However, mine was due to the fact that I had purchased the phone off e-Bay and the seller would not give me the old code to change it to a new code. After searching the web, I found that you can change the code by punching in:
*3001#12345# and then the "send/dial/answer" key
Then scroll down and select the "security menu" and it will show you the current security code. You can either keep it the same or change it. This worked with my Nokia 8260 TDMA phone. I don't know if it will work with all Nokias.