Everything Everywhere, which operates UK networks for T-Mobile and Orange, saw its largest-ever increase in new postpaid contracts last quarter, adding 313,000 month-to-month customers.
Last quarter, nearly half - 48 per cent - of the company's customers were on monthly contracts, up from 44 per cent in Q4 2010.
The company posted 2011 year-on-year service revenue growth of 2.1 per cent - excluding regulatory mobile termination rate (MTR) cuts - thanks in part to strong smartphone demand.
Olaf Swantee, Everything Everywhere Chief Executive Officer, said in a statement:
As a result of network sharing and customer experience improvements, we are seeing good commercial momentum and are capitalising on the smartphone and data opportunity to drive underlying growth.
Everything Everywhere's previous quarterly record for new postpaid customers was 300,000 in Q4 2010.
The company, which has nearly 28 million customers, grew its total customer mobile base by 72,000 in the fourth quarter.