Apple is allowing iPhone owners to use Internet calling services over cellular networks. Several companies offering VoIP services said this week that Apple now allows their applications to work on the iPhone.

VoIP calling has been available on the iPhone, but only over Wi-Fi connections, which don't have the range of 3G cellular networks.

Apple's earlier decision to block a Google calling application triggered an inquiry by the Federal Communications Commission, which is investigating competition in the wireless industry.

Apple said at the time that it blocked Google Voice because the program duplicated some of the iPhone's features, and that it was still studying the application.

Two months after the FCC sent letters to Apple, Google, and AT&T - the iPhone's exclusive U.S. wireless carrier - AT&T said it had tweaked its technology to allow VoIP services on the iPhone to work over its 3G wireless network, even though the services challenge AT&T's core calling business.

AT&T also revealed that Apple wasn't allowed to enable any Internet calling applications that use AT&T's 3G network without AT&T's permission. Apple vowed to get VoIP applications into its App Store.

FCC Chairman Julius Genachowski on Thursday praised Apple's latest decision, calling it "an action that will create new opportunities for entrepreneurs and provide more choices for consumers."