How do 0333 numbers differ from local numbers?

Instead of a local number with a city-specific area code, 0333 numbers are special UK landline numbers that aren’t linked to any particular location.  Yet calls to 0333 are billed at the same rate as standard landline calls, making them cost-effective for both businesses striving for national reach and their customers (as it costs them the same to call, regardless of where in the UK they are located).