how to get my at&t phone number on lumia 640
- Instruction for AT&T Microsoft Lumia 640 XL phone is simple & effortless. Just a few steps required to enter AT&T Microsoft Lumia 640 XL Unlock Code. Here is the simple AT&T Microsoft Lumia 640 XL Unlock Code Instruction 1  : Turn off your AT&T Microsoft Lumia 640 XL phone. 2  Insert non accepted network Sim Card.3  Turn on your AT&T Microsoft Lumia 640 XL phone.ust a few steps required to enter AT&T Microsoft Lumia 640 XL Unlock Code. Here is the simple AT&T Microsoft Lumia 640 XL Unlock Code Instruction 1  : Turn off your AT&T Microsoft Lumia 640 XL phone.