Deustche Telekom owned T-Mobile has acknowledged that some of its employees have sold the details of thousands of customers to third party brokers.
The BBC reports that the mobile phone network has already passed on more details to the Information Commissioner Office who will take legal action against the culprits.
The data was used by third party companies to cold call T-Mobile customers when they were approaching the end of their contracts to propose them new deals from rival networks.
The report also mentions "millions of records", which means that at least 1000 pieces of data per user were illegally obtained. These must at the very least include the name of the customer, his or her phone number and the expiry date.
There is a possibility that more than one entity might have purchased the data and that one or more of them might be T-Mobile partners. It must be noted that T-Mobile says that it was not aware of the transaction.
A spokesperson for the company added that "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."
T-Mobile has assured the ICO that it will collaborate fully during the course of the investigation and will "proactively supported the ICO to help stamp out what is a problem for the whole industry".
T-Mobile is the victim and not an active actor of this scandal, unless proven otherwise. Rogue employees exist everywhere and no big companies is immune from their actions. Some organisations simply choose to keep it silent in order not to attract negative publicity.