How To Use At&t Sim Card In Verizon Phone. You will need to call ATT and ask them for the unlock code for your phone. Have the SIM card mailed to you.

Refer to Account Roles for additional info. A SIM subscriber identity module card is a tiny memory chip that stores data about your cell phone use. Go to your device settings.
Have the SIM card mailed to you.
A dual SIM phone is one device that can have up to two active numbers plans or accounts. ATT prepaid devices need to be active for at least 6 months. This means that no other SIM card will work in your phone. GSM phones only on GSM networks.

