How to make an ATT  GSM NOKIA 6310i cellular phone work with different
SIMS cards? I could not use it in Europe using a local  SIM because it
aked for a code I did not have.  ATT does not share this code.

I'm answering it for someone else, since no one else seems to have
answered.  The problem is that your phone needs to be unlocked.  In
teh US, and many other countries, GSM phones are tied to a specific
provider.  By calling up ATT, you should be able to get them to unlock
it for you.  Then, it will work with other SIM cards.