(Telecompaper) Microsoft announced that it more than doubled the number of app downloads and gross sales on its Windows Store in 2014. Its efforts to attract more developers and apps for the Windows Mobile platform resulted in an 80 percent increase in registered developers and 30 percent increase in active users of the Windows Store. Sales were helped by a growing number of carrier billing agreements. After recently adding agreements with operators in markets such as Argentina, Brazil, Chile, China, Colombia, India, Mexico and Vietnam, the Windows Store had a total 81 connections across 46 markets. The company said average transaction volume increases eight-fold in emerging markets with carrier billing. It plans to work more closely with operators to promote the billing method to end-users.