AT&T has filed a lawsuit against three former employees who allegedly installed software on the company’s network to allow the unauthorized unlocking of “hundreds of thousands” of phones, GeekWire reported.

According to the suit, which was filed on Sept. 11 in the U.S. District Court for the Western District of Washington in Seattle, the employees were working with a company called Swift Unlocks to provide unlock codes for devices that were still under contract with the carrier. 

Unlocked phones can be used on any wireless network, making the lock codes an important retention tool for carriers. According to new rules from the FCC, carriers are now required to give customers an unlock code once their wireless contract is paid off.

The suit says AT&T became aware of the issue in late 2013, when it discovered an unusually large number of unlock requests had made using the credentials of two employees, named in the suit as Kyra Evans and Marc Sapatin. An investigation by the carrier determined that the requests had occurred “within milliseconds” of each other, “suggesting the use of an automated or scripted process to unlock devices, rather than manual submission of unlock requests in the ordinary course of business.” Further examination of the transactions revealed the presence of malware on AT&T’s protected computer systems.

In the filing, AT&T alleges that Swift Unlocks head Prashan Vira paid Evans at least $20,000 to install the malware and obtain the unlock codes, while Sapatin was allagedly paid $10,500 for his role in submitting the largest number of unlock codes.

Sapatin left his position at AT&T for “purportedly unrelated reasons” in October 2013, and was followed by Evans, who left in February 2014 after being placed on administrative leave.

A third AT&T employee, Nguyen Lam, was also discovered to have the malware on his work computer. Lam was fired by AT&T.

According to the filing, AT&T is seeking damages for “lost profits, lost goodwill and damage to its reputation”, recompense for the defendant’s profits with interest, injunctive relief and attorney’s fees.

AT&T said in a statement to GeekWire that the scheme did not have any adverse impacts on its customers.