Google has acquired US firm GrandCentral Communications, which offers users a single, lifetime phone number that can be linked to any phone or account – or combinations thereof – that for which the user has a subscription.

The announcement, expected for some days, was made on Google’s official blog. “We think GrandCentral’s technology fits well into Google’s efforts to provide services that enhance the collaborative exchange of information between our users,” said the search firm.

The single number given to subscribers by Grand Central allows them to select which callers go to which phone – work, home, mobile – and also provides a central mailbox for all services, which is available to access online. Different voicemail greetings can be set for different callers.

Until now, users have been able to upload their own ringback tones. While the GrandCentral solution is integrated into Google, however, services are being limited. The firm is restricting the number of sign-ups to its beta trial – launched in September 2006 – and the ringback service is being restricted to licensed, centrally stored content.

The terms of the deal have not been revealed.