Google Voice has not been approved for distribution to the iPhone, and on July 31, the FCC questioned Apple and AT&T about their treatment of that and other proposed iPhone applications. It also questioned Google about its iPhone application and the approval process for software on its own Android mobile platform. All three companies submitted responses on Friday.

Apple said it has not rejected the Google Voice iPhone application but is still studying it. In response to pointed questions, both Apple and AT&T said the iPhone maker did not consult AT&T about Google Voice and that the carrier has not been involved in evaluating it. They said Apple typically does not consult AT&T about decisions on what applications can be offered in the iPhone App Store.

Google Voice would let users make calls on the smartphone while also providing voicemail, text messaging and contact management features. The fact that it has not been approved for the iPhone has heightened criticism of the review process for iPhone applications, which critics say is murky and unpredictable.

(More to follow.)