A trio of public interest groups has informed AT&T that they intend to file a complaint with the FCC over the carrier's controversial FaceTime policy. 

Free Press, Public Knowledge and The New America Foundation's Open Technology Institute said in a letter to AT&T that the complaint is in response to its decision to block certain users from running Apple’s FaceTime application over its mobile networks. 

In the past, FaceTime has only been available over Wi-Fi, but Apple recently changed that with the release of iOS 6, the company's latest iteration of its mobile operating system. Both Verizon Wireless and Sprint have confirmed that they will not place any restrictions on use of the application over their cellular networks. 

Specifically, AT&T has said it will limit the use of Apple's FaceTime video-calling application to those customers who subscribe to its Mobile Share plans, which allow users to connect up to 10 devices to a single bucket of data. 

The groups argue that by blocking the application over its mobile network, even for some of its users, AT&T is in violation of the FCC's net neutrality rules. The regulations prohibit mobile carriers from blocking any application that competes with the provider’s voice or video telephony services.

The groups are asking AT&T to "reconsider its behavior and the impact that blocking FaceTime will have on its customers, particularly the deaf and hard of hearing, as well as all who use this application to communicate with family and friends over the Internet." 

AT&T has argued that its policy is within the FCC's net neutrality rules, noting that it does not have an application of its own that competes directly with Apple’s FaceTime. 

The groups say they plan to file the complaint with the FCC in the coming weeks. The FCC requires that anyone filing a formal complaint must give at least 10 days’ notice of their intent to file.