Testing the download and upload speeds of your smartphone with apps like Speedtest will no longer count against your monthly data allowance on T-Mobile. In the past, T-Mobile has relied on user-initiated tests from Speedtest to back claims that it offers the fastest 4G LTE data service in the United States. Millions of speed tests from real people using their own phones prove it, CEO John Legere said back in January. T-Mobile CTO Neville Ray showcased the carriers favorable Speedtest results at CES 2014.