Everything Everywhere, Britain's biggest mobile operator, said it added 201,000 contract customers in the fourth quarter, during which it launched Britain's first superfast 4G mobile broadband service.

The company, a joint venture between France Telecom and Deutsche Telekom, said more than half of its customers were now on contracts, reflecting the growing popularity of smartphones, as the company posted broadly flat adjusted core earnings.

EE posted full-year adjusted core earnings of 1.41 billion pounds, broadly flat on the year before, on revenue of 6.7 billion pounds, down 1.9 percent.

Its service revenue of 5.95 billion pounds, rose 2.7 percent excluding the impact of regulatory price changes.

(Reporting by Paul Sandle, Editing by Brenda Goh)