T-Mobile has been on the warpath with its “uncarrier” initiative and it looks like the company’s moves are starting to pay dividends. In an interview with CNET, T-Mobile CMO Mike Sievert said that the carrier added a company-record number of subscribers in August. T-Mobile last month posted a quarterly net addition in postpaid subscribers for the first time in four years so it seems that the company has continued to build its momentum all summer. T-Mobile, which has long struggled as America’s No. 4 wireless carrier, has received a jolt this year after ditching wireless contracts while also giving customers the option to upgrade their phones more regularly in exchange for paying an extra $10 a month.