T-Mobile reported adding more than 1 million net branded postpaid customers in the first three months of 2018 as its latest quarterly results largely eclipsed Wall Street expectations.

The carrier said that total included 617,000 net postpaid phone additions, and officials reported branded postpaid phone churn of 1.07 percent.

Wall Street forecasters had expected 623,000 net phone additions and 819,000 added net postpaid connections overall, according to a note from Wells Fargo, while postpaid phone churn came in below the firm's forecast of 1.16 percent.

Prepaid T-Mobile customers, meanwhile, increased by a net of 199,000, also ahead of Wall Street expectations. Along with 229,000 net added wholesale customers, the carrier touted net connections that increased by more than 1.4 million overall.

The results were reported two days after T-Mobile and Sprint announced a long-sought agreement to merge into what would be the nation's No. 2 wireless carrier.

"2017 was a transformational year for our network and our distribution footprint and we’re off to a running start in 2018," CEO John Legere said in the company's earnings call, according to a transcript.

The carrier reported $10.5 billion in total revenues for the quarter — including $7.8 billion in service revenues and $2.4 billion in equipment revenues — and $3 billion in adjusted earnings. The revenue and earnings totals each beat the Wall Street forecasts of $10.3 billion and $2.9 billion, respectively.

The first quarter report also noted that T-Mobile has already deployed its 600 MHz spectrum holdings in 823 communities across 31 states, and company officials heightened the forecast range for postpaid net customer additions and adjusted earnings for the full calendar year.

"In a quarter in which customer volumes were light, [T-Mobile] still achieved impressive postpaid net phone adds in part by delivering record-low postpaid phone churn," Wells Fargo analysts wrote.