AT&T has just done another about face. Earlier the phone giant said that it "does not manage or approve applications" for the App Store.

But their response on Friday to a Federal Communications Commission's inquiry indicates otherwise. The federal agency had asked Google, Apple and AT&T to respond to a series of questions about the rejection of the Google Voice iPhone application by Apple.

AT&T acknowledged that it plays a role in authorizing VoIP applications. The AT&T response states: "AT&T and Apple agreed that Apple would not take affirmative steps to enable an iPhone to use AT&T’s wireless service (including 2G, 3G and Wi-Fi) to make VoIP calls without first obtaining AT&T’s consent."

Apple confirmed this in their response, stating: "There is a provision in Apple’s agreement with AT&T that obligates Apple not to include functionality in any Apple phone that enables a customer to use AT&T’s cellular network service to originate or terminate a VoIP session without obtaining AT&T’s permission."

While Apple took responsibility for the Google Voice blocking, these letters highlight AT&T's role in blocking VoIP applications such as Skype on its 3G wireless network

"The FCC's inquiry into Google Voice has ripped back the curtain on the wireless market and revealed AT&T's secret veto power over applications on the iPhone that offer consumers voice services over the Internet," said Ben Scott, policy director of Free Press.

It seems that Google Voice may not have been caught by AT&T's condition, but the popular Skype application for 3G was.

"AT&T's letter suggests they may reconsider permitting the Skype application in the face of this scrutiny," Scott added. "But the potential chilling effect of AT&T’s gatekeeper power is critical reminder of why the FCC must protect consumers."

The FCC inquiry has exposed the central issue of who controls the mobile Internet. It's time for the FCC to pass new rules to prohibit exclusive pacts between device manufacturers and network owners, especially those that allow for violations of Net Neutrality.