T-Mobile has emerged as the mystery firm that sold personal details of customers in exchange for “substantial sums” of money.
The scandal surfaced yesterday as the UK Information Commissioner's Office (ICO) claimed that staff at an undisclosed firm sold “millions of records from thousands of customers without their knowledge”.
It is alleged that the data was sold to other firms who would then cold-call the customers as their mobile contracts neared expiry.
As the story went live, a flood of mobile phone companies made statements declaring they were not subject to the investigation.
And as 02, Vodafone, Orange, 3 and Virgin said they were not part of the scandal, T-Mobile confirmed it was the group in question.
A T-Mobile spokesman said the data had been sold "without our knowledge".
Christopher Graham of the ICO said he is seeking to prosecute T-Mobile on the matter. He said yesterday that the scandal showed why prison sentences should be established for this kind of data theft.
A T-Mobile spokesperson said: "T-Mobile takes the protection of customer information seriously.
"When it became apparent that contract renewal information was being passed on to third parties without our knowledge, we alerted the Information Commissioner's Office.”
The spokesperson said T-Mobile kept the scandal quiet in order to stop any criminal cases being prejudiced. The firm has not yet been charged of any criminal offence, has no date set for court, and is not certain will be prosecuted on the matter. A clearer picture on the incident needs to be established.
T-Mobile said the affair was “deeply regrettable", and that the group is working with the ICO to help identify the source of the breech.