How to unlock AT&T Samsung SGH-A157 for FREE.
SGH-A157 Network unlock procedure:
Step 1: Remove sim card from phone and turn the phone on.
Step 2: Dial *2767*3855# This will initiate a Full reset for Samsung A157
Step 3: Once the phone restarts, dial #*7337# This will remove sim lock and reset phone
Step 4: Now insert your sim card. and restart the phone.