I have an unlocking code that I just received from AT&T. The CSR gave instructions that specified that I must have a SIM card inserted from my new carrier prior to unlocking the phone. I am planning to carry this phone overseas and have not yet purchased the card. I would like to know if this is necessary and also since the new card will belong to China Mobile, what if the next time I use the phone is in France and I purchase a European SIM card that is also GSM will I have to go through the unlocking steps again. I guess I don't get the unlocking thing. Clarification might help.
Thanks in advance
