(Telecompaper) T-Mobile US reported a strong increase in customer numbers and smartphone sales for the fourth quarter, but underlying service revenues were still lower year-on-year due to its challenger pricing strategy. The mobile operator added a net 1.6 million new customers in the three months and 4.4 million over the full year 2013, taking its base to 46.7 million at year-end. Quarterly service revenues, pro forma for its takeover of MetroPCS, were down 1.1 percent from a year ago to USD 5.17 billion, but the annual dropped improved from a 4.6 percent fall in Q3. Adjusted EBITDA declined to USD 1.24 billion from USD 1.36 billion a year earlier, hurt by the higher smartphone sales and promotions for new offers. Over the full year, the company met its guidance for adjusted EBITDA at USD 5.3 billion, and T-Mobile said it expects this to improve to USD 5.7-6.0 billion in 2014, helped by higher-than-expected synergies from the MetroPCS integration. Capital expenditure is expected to increase slightly to USD 4.3-4.6 billion this year from USD 4.2 billion in 2013.