T-Mobile Inc. TMUS, +0.18% shares slipped in the extended session Thursday after the telecom company reported it posted record-high customer results for the quarter. T-Mobile shares declined 1.4% after hours, following a 0.2% rise to close at $115.57. The company said it added 844,000 net postpaid phone customers in the fourth quarter, compared with 824,000 in the year-ago quarter. Postpaid net customer additions grew to 1.75 million — the highest in company history, it said — from 1.62 million in the previous quarter. For the year, T-Mobile said it added 2.92 million net postpaid customers, compared with 2.22 million in the previous year. Total customers rose to 108.7 million from 102.1 million in the year-ago period.
