Google has announced plans to give every homeless person in San Francisco a phone number and a voicemail account that they can check from any phone in the city.

The scheme has been set up using the infrastructure from Grand Central, a telecoms routing firm Google acquired last year. Over 4,000 voice mailboxes have been set up for the purpose.

"We are firm believers in the power of technology to improve the daily lives of individuals and communities as a whole," said Craig Walker, a senior product manager of voice products for Google.

"Access to phone and voicemail services is one way that Google can help San Francisco's homeless stay connected with family, friends, social workers, health care providers and potential employers."

The scheme is being promoted in homeless shelters around the city as part of Mayor Gavin Newsom's Project Homeless Connect.

"Providing phone and messaging capabilities is an extraordinary step forward in the city's commitment to addressing the needs of this vulnerable community," said Newsom.

The scheme will let homeless people access voicemails by typing a special code into any phone and will let them record a greeting for callers.