BELLEVUE — T-Mobile US Inc. on Thursday reported fourth-quarter net income of $101 million, after reporting a loss in the same period a year earlier, as more people signed up for its wireless service.

T-Mobile said it ended the year with more than 55 million customers after adding 2.1 million in the fourth quarter and 8.3 million during the year. It has heavily promoted discounts to win customers from other carriers.

The Bellevue company said it had a profit of 12 cents per share.

The results beat Wall Street expectations. The average estimate of analysts surveyed by Zacks Investment Research was for earnings of 9 cents per share.

The wireless carrier posted revenue of $8.15 billion in the period, which also topped Street forecasts. Analysts expected $7.91 billion, according to Zacks.

For the year, the company reported a profit of $247 million, or 30 cents per share. Revenue was reported as $29.56 billion.

T-Mobile shares closed at $31 Wednesday and have risen 15 percent since the beginning of the year. The stock has fallen nearly 1 percent in the last 12 months.