WhoCallsYou

UK phone companies

Ofcom gives blocks of phone numbers to 405 companies. Each company uses them for its own customers or passes them on to businesses and internet phone services. The company that holds a range is not necessarily the one that called you.

All range holders

Source: Ofcom numbering data. A block is a group of up to 10,000 or 100,000 numbers that start with the same digits.