https://www.bleepingcomputer.com/news/security/atandt-lost-200m-in-seven-years-to-illegal-phone-unlocking-scheme/

A Pakistani fraudster was sentenced to 12 years in prison earlier this week after AT&T, the world's largest telecommunications company, lost over $200 million after he and his co-conspirators coordinated a seven-year scheme that led to the fraudulent unlocking of almost 2 million phones.

Throughout this operation, Muhammad Fahd — the scheme leader — bribed multiple AT&T employees to do his bidding, including unlocking phones, giving him access to their credentials, and installing malware that gave him remote access to the mobile carrier's servers.