The new service weaves traditional phone features with Google's Gmail email product, allowing a person to store transcripts of voicemail phone messages in their email inbox and to find a specific nugget of information within a phone message as if trawling through a sea of emails.

The move comes as Google increasingly branches out from its stronghold in Internet search, as it seeks to carve out a role in everything from cell phones to personal productivity software.

And it demonstrates the company's ability to fuse various technologies -- home-grown and acquired -- into new products, even as the economic recession puts the future of certain Google projects in question.

Google Voice is based on the technology of Grand Central Communications, a company that Google acquired in July 2007. After Grand Central remained silent for nearly two years under the Google flag, some observers wondered whether it had met the same fate as Dodgeball, a Google acquisition that was formally shut down this year.

Google Voice represents the first major update to Grand Central since the acquisition. Like the original Grand Central product, Google Voice offers consumers a single phone number that can route incoming calls to home, office and cell phones.

The new version uses speech-recognition technology that Google developed for its Goog-411 telephone directory service, automatically transcribing voicemails into text. The transcribed messages can be forwarded as an email or SMS text message to a person's email inbox.

It is unclear how Google Voice will fit into Google's business model, which relies on advertisers to provide 97 per cent of the company's revenue. The company has also ventured into the mobile software market, launching last year the Android mobile operating system.

Other than a feature that bills Google Voice users when they make long-distance phone calls, the product has no immediate means of generating revenue, said Craig Walker, group product manager for Real Time Communications at Google.

He said that Google Voice, which will be available to existing Grand Central users on Thursday and to the general public in the following weeks, provides another reason for people to spend more time on Google's various online properties, which benefits the company.

Google also makes money from selling enterprise versions of its applications to corporations. But Walker said the current priority is to make Google Voice a success as a free consumer product.