Google Voice has 1.4 million subscribers including 570,000 daily users, according to a compromised filing with the US Federal Communications Commission. Google blamed a formatting gaffe for accidentally releasing confidential statistics as a PDF on the regulator’s Web site. “We had intended to keep sensitive information regarding our partners and the number of Google Voice users confidential,” the company said in a statement.

The subscriber figures compare to 483 million registered Skype accounts, indicating Google has some way to go before establishing its VoIP platform as a significant player. Its 570,000 daily users compare to the 19.5 million peak reported by Skype last month but have been enough to instill fear in traditional carriers such as AT&T, whose complaints over call blocking prompted the FCC to probe the Google service.

In the filing, Google owned up to blocking access to certain rural phone numbers known for pumping up termination fees. “In August 2009 Google Voice began the practice of restricting calls to cer- tain high-cost destinations,” it said, claiming it was not technically a phone company and was therefore not bound by rules requiring universal termination. AT&T cried foul, escalating a battle that kicked off earlier this year when Google Voice was rejected from the iPhone App Store.

The filing also provides a look under the hood at the fledgling platform. Global Crossing and Level 3 Communications are providing backbone transit for Google Voice. iBasis is apparently handling outbound international calls, with carrier lookup and porting services provided by Neustar. Google said Syniverse Technologies supported its free texting service while Broadvox Communications, Bandwidth.com and Pac-West Telecomm are also involved.

Google meanwhile revealed it plans to take the VoIP service international in the near term. The company said it had inked deals with several unspecified “international service providers for inputs to Google Voice.”