Apple told the Federal Communications Commission on Friday that it did not reject an iPhone application submitted by Google and that it was still studying it, in part because of privacy concerns.

Apple was formally responding to a commission inquiry into the reason the Google Voice service, which offers users free domestic telephone calls, deeply discounted international calls and SMS messages, had not been allowed into the Apple iPhone App Store.

Apple said in a letter to the F.C.C. that Google Voice duplicated the functions of the iPhone, which uses the AT&T network in the United States, and might confuse users. The application “appears to alter the iPhone’s distinctive user experience by replacing the iPhone’s core mobile telephone functionality and Apple user interface with its own user interface for telephone calls, text messaging and voice mail,” the letter said.

Apple also raised concerns that Google Voice copied all of the information about a user’s contacts onto Google’s servers. “We have yet to obtain any assurances from Google that this data will only be used in appropriate ways,” the letter said.