WASHINGTON — Federal regulators will look into complaints by AT&T that Google's messaging and calling service, Google Voice, blocks calls to rural communities where local phone companies charge high connection fees.

The Federal Communications Commission sent a letter Friday to Google requesting information about its Voice service, which lets people sign up for one number that can route incoming calls to cell, office or home phones. It also lets users place calls, including international calls, at low rates.

AT&T has complained that Google Voice blocks calls to some rural communities to reduce what Google has to pay in access charges. AT&T and other big phone companies have to carry such calls.

Google had no immediate comment.