T-Mobile this week revealed its fourth quarter and full-year 2013 financial results, highlighting huge subscriber gains and strong earnings for the smallest of the four major U.S. telecoms.

The biggest news for T-Mobile investors would be the company’s net subscriber gains during the fourth quarter – 869,000. This number represents yet another quarterly increase in subscribers, up from the 648,000 net subscribers the company gained during the third quarter of 2013.

Including prepaid , unbranded, and mobile broadband customers, T-Mobile’s total net customer base rose by a net 1.6 million during the fourth quarter. This adds to previous positive quarters and puts the company’s net 2013 customer gain at 4.4 million, making up for the 256,000 customers the company lost during its 2012 financial year.

T-Mobile’s fourth quarter earnings did not follow the trajectory of it subscriber gains, with pre-tax earnings of $1.24 billion on revenues of $6.83 billion. This is down 7.8% from the $1.34 billion the company earned during the third quarter of 2013 and down 8.5% from the $1.35 billion earned during the fourth quarter of 2012. Company revenues continued their upward trend during the fourth quarter, rising 2.1% quarter-over-quarter to $6.83 billion.

Despite the lower earnings, T-Mobile had other encouraging signals in its latest financials. During the fourth quarter the company posted a record (for T-Mobile) 6.2 million smartphone sales. It also reported a year-over-year rise in its branded postpaid upgrade rate to 9% for the fourth quarter 2013.

“Our performance in the fourth quarter and the full year is clearly proving that we have our strategy right and that we are executing it well,” said John Legere, CEO of T-Mobile. “Customers are fed up with the old ways and are voting in favor of choice, innovation and doing business with a company that cares about them and is willing to earn their business. For shareholders, we transformed the company into a fierce, growing competitor that is changing the wireless industry and creating significant value.”