AT&T said on Tuesday that it would no longer prevent customers with the Apple iPhone from using Internet telephone services that bypass its own voice network.

Until now, AT&T would not let users of voice services like Skype connect over its wireless data network. The Skype application on the iPhone could make calls only when connected to a Wi-Fi network.

The issue of what sorts of services wireless carriers should allow has become the subject of scrutiny by the Federal Communications Commission, which is considering a proposal to formalize its network neutrality principles and extend them to cellphones. Those principles prohibit carriers from blocking competitors’ services and applications.

Skype, which eBay is selling, made a formal complaint to the commission two years ago, saying it was being blocked on AT&T’s iPhone. But the issue did not get much attention until Julius Genachowski was appointed commission chairman by President Obama.