T-Mobile US Inc on Thursday posted its first net profit in a year, raised its forecasts for subscriber growth and reported the most postpaid phone subscriber additions in the industry. What matters most for T-Mobile and Sprint is subscriber growth, said Cowen Group analyst Colby Synesael. Three to five years from now, your revenue growth will be largely capped by how big that base is. Last year T-Mobile turned around years of subscriber losses through campaigns that have eliminated contracts, restructured pricing plans and sparked price slashing across the industry. T-Mobile added 1.5 million net customers in the second quarter and 102,000 net prepaid subscribers, compared with prepaid subscriber losses for the top four wireless carriers.