SK Telecom reported first-quarter sales of KRW2.877 trillion (US$2.2 billion), up 1.4 percent from a year earlier on a small increase in subscriber numbers, reports Telecompaper. The South Korean operator posted operating income of KRW564 billion, up 1.8 percent thanks to lower marketing costs, while net profit fell 17.3 percent to KRW316.7 billion due to valuation losses related to exchange rate fluctuations.