By Rory Cellan-Jones
Technology correspondent, BBC News
Spinvox has spoken several times to the BBC about its technology
A UK firm that turns mobile messages into text faces questions over its privacy standards, technology and finances following a BBC investigation.
Spinvox's service aims to convert voice messages into text messages using advanced speech recognition software.
But claims to the BBC suggest that the majority of messages have been heard and transcribed by call centre staff in South Africa and the Philippines.
The firm issued a statement calling the claims "incorrect" and "inaccurate".
"Speech algorithms do not learn without human intervention and all speech systems require humans for learning - Spinvox does this in real-time," the firm said in a statement.
"The actual proportion of messages automatically converted is highly confidential and sensitive data," it added.
The Spinvox website claims its technology "captures spoken words and feeds them into a Voice Message Conversion System, known as 'D2' (the Brain)".
The company said that, when necessary, parts of messages can be sent to a "conversion expert".
The part sent is anonymised so that there is no way of tracking back a particular number or person. It will be just one of millions of messages going through the automated system on a particular day, the company said.
A Facebook group created by staff at an Egyptian call centre, which used to work for Spinvox, includes a picture of one transcribed message containing what appears to be sensitive commercial information.
It also includes an audio recording of one call, and pictures of staff at the call centre.
Spinvox said that the pictures relate to a training session, and that the call centre did not meet its stringent standards and never handled live calls.
However, the BBC has spoken to Kareem Lucilius, who said he worked for six months at the call centre, alongside as many as 150 others.
He said that after initial training, he went on to transcribe live messages. Asked what part machines played he said, "It was done 100% by people".
He described the work: "We heard the message from the very beginning to the very end. Love messages, secret messages, messages with sexual content, even people threatening to kill each other."
Other call centre staff in South Africa and the Philippines have discussed on blogs how they have also transcribed calls for Spinvox.
A source at the company has told the BBC that the vast majority of messages are in fact converted into text by staff at call centres.
The fact that messages appear to have been read by workers outside of the European Union raises questions about the firm's data protection policy.
The firm's entry on the UK Data Protection Register says it does not transfer anything outside the European Economic Area.
The Information Commissioner's Office (ICO) told the BBC that it has contacted Spinvox "to ensure that its entry on the data protection register is both accurate and complete, especially with regards to the transfer of personal data outside the European Economic Area".
In a statement, the ICO explained there was nothing to prevent Spinvox from using people rather than machines to translate messages.
However, it said that "it may be helpful if the company is clearer about the likelihood that people will be used to translate messages".
"This is particularly important if customers are using the service for transmitting sensitive or secure information," it added.
The firm issued a statement via its blog on Thursday saying that the allegations of call centres handling a majority of calls were "incorrect".
"We have always been absolutely clear in our communications that humans form an important component of our learning system," it said.
It added that the human-mediated training of its system was accomplished "in total security through anonymisation, encryption and randomisation".
Spinvox, which has raised more than $200m (£120m) from investors, was founded in 2004.
The company source told the BBC that operating large numbers of call centres is putting a huge financial burden on the business.
Last week the company's co-founder Christina Domecq appealed to staff to take all or part of their pay for the months of July and August in the form of share options.
Is Spinvox a major technology success story, cracking the age-old problem of getting a machine to understand the human voice in all its glorious, cacophonous varieties? Not yet, it isn't
In an e-mail to staff she explained that the target was to raise £1m to see the company through to profitable status.
But she warned that "should we not achieve the uptake we need, unfortunately, we may have to explore further cost-cutting measures".
Daniel Doulton, the firm's other co-founder, told the BBC that it was true that the company had suffered some growing pains because of the exponential growth it was enjoying - bringing it 100 million customers around the world.
"The business now operates profitably," he said. "We are going through enormous growth as a business."
The BBC has also learned that Spinvox has been locked out of one of its London data centres, leaving it unable to get access to its servers after a dispute about payments.
A spokesman at ANLX, the company which runs the data centre, said "their access has been suspended. We are reviewing our options on a day-to-day basis."
Spinvox said it cannot comment on the dispute, but said its main data storage locations are not affected.
The company says it works with some of the world's biggest telecoms companies and institutional investors who, following due diligence and audit, have gone on to sign contracts with the voice-to-text firm.
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