This document from "The Unlocker" website provides a guide on how to remove an AT&T device from the lost or stolen blacklist, also known as unbarring or IMEI cleaning. It explains the problem of purchasing a blocked device and then offers a step-by-step process using external server services to verify the device and carrier status and perform the unbarring service. The article clarifies that this process is for reversing stolen status, not for network unlocking, and primarily focuses on AT&T devices but mentions resources for other carriers. The author also promotes their paid services for those interested in starting a device unlocking business.

https://theunlocker.tech