T-Mobile said Tuesday its revenue in the January-March period exceeded analysts’ estimates, soaring 78% from a year earlier, but costs tied to its merger with Sprint weighed on profit.

The Bellevue-based cellphone-service provider posted first-quarter revenue of $19.8 billion, boosted by its merger with Sprint. Profit fell 1.9% to $933 million, or 74 cents per share, as expenses rose because of the merger. Analysts expected T-Mobile to report adjusted revenue of $18.9 billion, according to Investor’s Business Daily.

T-Mobile said it ended the first quarter with about 20% of Sprint customers moved to its network, and it now has a record-high 103.4 million total customers after 1.2 million postpaid net additions during the quarter. It was the fourth quarter in a row that T-Mobile added more than 1 million new customers.

The company also boosted its outlook for the year. It now expects postpaid net customer additions of 4.4 million to 4.9 million in 2021, up from prior guidance of 4 million to 4.7 million. But T-Mobile also forecast higher merger costs this year — $2.7 billion to $3 billion before taxes, up from $2.5 billion to $3 billion — that will reduce profits.