T-Mobile US (NASDAQ:TMUS) on Thursday reported lower-than-expected postpaid phone additions, which cast a shadow on its forecast raise and strong top and bottom line numbers in its first-quarter earnings report.

The news offset the carrier’s better-than-expected financial results. T-Mobile posted earnings per share (EPS) of $2.58 on revenue that grew nearly 7% year-over-year to $20.89 billion, both above forecasts.

T-Mobile US posted better-than-expected first-quarter results on Thursday, but its main wireless business grew somewhat slower than expected.The stock fell more than 5% in premarket trading Friday.T-Mobile said first-quarter adjusted earnings were $2.