Three Mobile admitted the data breach late Thursday, saying that computer hackers gained access to a Three Mobile customer phone upgrade database containing the account details of nearly 6 Million customers. According to multiple British media reports, hackers used an employee login to gain entry into the database. The stolen data includes customer names, addresses, phone numbers and dates of birth, which is then used to carry out mobile phone fraud. Three has confirmed around 400 cases in which fraudsters had stolen high-value handsets through burglaries and 8 devices have already been illegally obtained.
Source: https://thehackernews.com/2016/11/3-mobile-uk-hacked.html