PORTLAND, Ore. — Google is aiming to take a bite out of long-distance carriers' market share by enabling free calls over the Internet from Blackberry and Android handsets.

Google Voice, which directs calls to users' home, work and mobile phone numbers simultaneously, works with a downloadable application, which permits free voice-over-Internet (VoIP) calls to be routed from call centers to destinations in the U.S. and overseas.

The "Google Voice service is similar to what Skype is doing in the U.K. using a carrier's normal voice channels for the first leg of a long-distance call, which is then routed from their call center over the Internet to the destination," said Tole Hart, research director at Gartner Inc. "The service will be useful mainly for international calls since most domestic long-distance plans at the major carriers are already at a flat rate."

Users of Blackberry and Android phones can download the free application into their handsets. Once installed, Google said calls would then be routed through Google's call center using VoIP connections.

Google Voice also archives transcripts of voicemails and uses a voice recognition algorithm to highlight words in voice messages as they are being played back. The archive also stores text messages while providing access to worldwide directory assistance via Goog-411. Some data charges may be incurred from carriers along with fees for international calls from Google.

Google acquired the technology two years ago when it acquired GrandCentral, which pioneered the concept of using VoIP to enable users to have one number for all phones along with a central voicemail inbox.

Google has since been enhancing features by adding voice recognition to compile transcripts and other applications such as letting users listen as voicemail is being recorded so they can break in for important calls.

The new mobile application allows Blackberry and Android phones to dial numbers directly from their existing address books, and send text messages, directly to international destinations with Google Voice handling call routing over the Internet to bypass long-distance charges.

Non-Blackberry and Android users can download a mobile Web application that provides browser access to Google Voice features.