AT&T Inc. is urging the Federal Communications Commission to investigate Google Inc.'s Google Voice service on grounds it may be violating federal telecommunications laws.
The phone giant based its request on news reports that said Google Voice restricts users from placing calls to certain areas with carriers that charge high access fees. Under federal law, other telephone service providers don't have that option.
"By blocking these calls, Google is able to reduce its access expenses," AT&T said in a letter it sent Friday to the FCC.
The complaint was the latest in a fight that's been intensifying between the companies.
A few weeks ago, in a separate spat, Google wrote a letter to the FCC expressing its dismay that Apple Inc. had rejected Google Voice for its iPhone app store. Some industry observers have said that the service could potentially compete with AT&T, the iPhone's exclusive U.S. carrier.
In the latest scuffle, AT&T also contends that Google Voice violates the FCC's "net neutrality" guidelines, which say consumers are entitled to competition among network and service providers.
AT&T asserts that Google breaks the rules by "openly flaunting the call-blocking prohibition that applies to its competitors."
On a company blog, Google's telecom and media counsel, Richard Whitt, said Google Voice should be allowed to block the calls because it is not a traditional phone service.
"Unlike traditional carriers, Google Voice is a free, Web-based software application, and so not subject to common carrier laws," he said.
Google Voice is a service that centralizes people's mobile and land-line numbers and their messaging to one number.
"Google Voice is not intended to be a replacement for traditional phone service -- in fact, you need an existing land or wireless line in order to use it," Whitt said. "Importantly, users are still able to make outbound calls on any other phone device."