Another crisis has hit T-Mobile in the UK, following revelations that the carrier’s staff had sold customer details to a rival network.
It is believed that tens of thousands of customers had their confidential contract details sold.
The security breach follows a similar incident at T-Mobile's German division last year which resulted in a crack down on security.
The UK’s Information Commissioner's Office (ICO) has been investigating claims that employees engaged in illicit commercial transactions relating to customers' mobile phone contracts, including their contract expiry dates.
The buyers of the information, believed to be the operators’ competitors, then used the material to cold call customers prior to contract expiry dates to offer them an alternative contract.
According to the initial findings from the ICO, the information was sold on to several brokers and “substantial amounts of money” changed hands. The wide scale investigation involves the granting of several search warrants with the ICO now compiling a prosecution file.
The ICO has already described the operation as the “the biggest data breach of its kind”.
The Information Commissioner, Christopher Graham said, "we are considering the evidence with a view to prosecuting those responsible and I am keen to go much further and close down the entire unlawful industry in personal data. But, we will only be able to do this if blaggers and others who trade in personal data face the threat of a prison sentence."