AT&T is suing three former employees who the telecommunications giant claims were paid by another company to place malicious software programs on AT&T phones, PCmag.com reported.

Marc Sapatin, Nguyen Lam and Kyra Evans were named in a complaint filed by AT&T with Seattle’s U.S. District Court last week. The trio worked at an AT&T call center in Washington in 2013 and allegedly participated in a scheme to install illegal unlocking software. When a phone is unlocked, according to the complaint, “it can be used on multiple carrier systems rather than exclusively with AT&T,” a change which cuts directly into the heart of AT&T’s business model.

Along with the three named defendants, 50 John Doe defendants were listed on the complaint. AT&T has not specified the amount of financial damages it’s seeking yet.

AT&T says a company called Swift Unlocks, operated by Prashant Vira, “paid Evans at least $20,000” for her role in the scheme. Sapatin was allegedly paid at least $10,500.

The breach is all the more significant given the revelation last month that AT&T handed over more than 1 billion domestic cellphone calling records per day to the NSA since 2011.

AT&T said no customer data was leaked, according to a statement issued to Ars Technica.

The partnership between AT&T and the NSA came to light from the documents leaked by former NSA systems analyst Edward Snowden. Other telecommunications companies worked with the NSA, too, but AT&T’s relationship was described as being “highly collaborative.”