The Federal Communications Commission has launched an inquiry to seek information on Apple’s rejection of Google’s voice application for the iPhone.

In letters sent to Apple and AT&T, the FCC has asked for details about Apple’s rejection of Google’s voice application for the iPhone and removal of related third party applications from Apple’s application store.

In the letter to Apple, James Schlichting, acting chief of the Wireless Telecommunications Bureau, wrote: “In light of pending FCC proceedings regarding wireless open access and handset exclusivity, we are interested in a more complete understanding of this situation.”

The commission has also asked about the role of AT&T, the exclusive US iPhone carrier, in Apple’s decision. The letter also seeks details of whether Apple consulted AT&T in the process of rejecting the voice application.

Earlier, Apple rejected iPhone applications based on Google Voice and the GV mobile application. These applications have been rejected reportedly as they duplicate the features that come with the iPhone.

Google Voice service assigns one number for all user’s calls and SMS. It reportedly allows users to receive calls from multiple phone numbers and make inexpensive international calls.

The FCC has also sent a letter to Google, seeking description of the proposed Google Voice application for the iPhone and whether Apple has approved any other Google applications for its App Store. The commission also asked about the explanation given by Apple to Google for its rejection of the iPhone application.

The commission has asked the companies to submit their responses before 21st August 2009.