Corporations and governments alike are hungry for data on people. In addition to internet behavior records and mobile phone metadata, there is a little-known digital bounty they are after – voiceprints – and they’re harvesting them in their millions.

Corporate and government databases in the US, Europe and elsewhere contain more than 65 million samples of people’s voices, AP reports, citing interviews with dozens of industry representatives. Voiceprints are increasingly used for user identification, much like people recognize each other by voice.

"There's a misconception that the technology we have today is only in the domain of the intelligence services, or the domain of 'Star Trek,'" said Paul Burmester, of London-based ValidSoft, a voice biometric vendor. "The technology is here today, well-proven and commonly available."

Last year the industry brought in revenue of just under $400 million, according to estimates voiced by Dan Miller, an analyst with Opus Research in San Francisco. In 2015, it is expected to skyrocket to between $730 million and $900 million.

"The general feeling is that voice biometrics will be the de facto standard in the next two or three years," said Iain Hanlon, a Barclays executive.

A bigger part of voiceprint usage is by clients of banks to get access to financial services. Providers say recognition technology now is accurate enough to ensure accurate positive confirmation.

"We've done a lot of testing, and looked at siblings, even twins," said John Buhl, executive at Vanguard Group, a Pennsylvania-based mutual fund.

"Even people with colds, like I have today, we looked at that," he said in a somewhat hoarse voice in a phone interview.

Sometimes bank clients may not even suspect that voiceprint recognition is in effect. For example, two major US banks, JPMorgan Chase & Co. and Wells Fargo & Co., use a voice screening system provided by matching the voiceprints of people calling them against a database of fraud suspects to prevent identity theft.

Of course, running the system in secret may be frowned upon and may be even illegal in some states. AP cites a legal document dated August 2013, in which the Israel-based biometrics company NICE Systems Ltd. advises its bank clients on giving legal ground for creating a consortium of companies that would share a blacklist of voiceprints.

The memo suggests altering the welcome message to include a notice that the call “may be monitored, recorded and processed for quality assurance and fraud prevention purposes."

"Creating a voiceprint from the call falls under 'processing,'" the memo explains. "Sharing the voiceprints within the consortium is for the purposes of fraud prevention."

Governments are catching up with the corporate world, too. In the US, voiceprints are used to monitor inmates and track offenders on parole – a landline phone call may substitute a visit to the precinct. New Zealand has collected over 1 million voiceprints, which are used by the Internal Revenue Department. South Africa’s Social Security Agency pays pensions to roughly 7 million people after verifying via a voiceprint that the recipient is still alive.

Privacy advocates are expectedly concerned with giving governments or corporation more info to play with. Voiceprint popularity is a potential surveillance tool, they say.

"It's more mass surveillance," said Sadhbh McCarthy, an Irish privacy researcher. "The next thing you know, that will be given to border guards, and you'll need to speak into a microphone when you get back from vacation."