unlocking a nokia 3120

[knowkeya]

I had this old Nokia 3120 2 years ago and now my new phone got stolen :( and I want to use the old Nokia with another provider's sim card.

The Nokia 3120 is locked to the Optus network.
Can someone please help me unlock it?

Please send me a Private Message if you have a kind heart.

[knowkeya]

Ok, I managed to get the "SIm card restriction" off. So, it's no longer locked to the Optus network.

Now, the phone is still asking me for a security code when I turn it on. Why?

Does someone know what I can do?