The U.S. Justice Department has announced that Pakistani Muhammad Fahd has been sentenced to 12 years in prison for leading the seven-year AT&T phone-unlocking malware scheme that began in 2012, Threatpost reports.

AT&T employees at a call center in Bothell, Wash., had been bribed by Fahd and his now-deceased accomplice to provide their credentials in an effort to infiltrate mobile phones belonging to AT&T customers under contract. The call center employees were then asked to install malware and hacking tools enabling remote unlocking from Pakistan, court documents showed. Nearly 2 million mobile phones had been unlocked by Fahd, resulting in more than $200 million in lost subscription fees for AT&T.

"Unlocking a phone effectively removes it from AT&T's network, thereby allowing the account holder to avoid having to pay AT&T for service or to make any payments for purchase of the phone," said the Justice Department.

Fraudsters have been known to target in-store and call center employees in their schemes, with AT&T having been sued in 2018 after its employees had been found to take part in a SIM-swapping scheme.