Even though I am not a customer, I found this interesting. For those who are customers and looking to get a new phone right now, you might want to wait a little bit.
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"T-Mobile is opening up more lanes on its information highway, but you'll need a new phone to drive on them. The carrier has started to deploy LTE-U, which pipes LTE signals over unused 5GHz Wi-Fi channels to enhance capacity. The carrier's use of 20MHz of LTE-U makes it much easier for it to deploy gigabit LTE, which requires 50MHz of LTE spectrum. T-Mobile made the announcement today because the FCC approved LTE-U after a long tussle with the Wi-Fi alliance over LTE-U's coexistence with Wi-Fi. LTE-U will require new phones, though."
http://www.pcmag.com/news/351905/t-mobiles-next-speed-boost-requires-new-phones
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"T-Mobile is opening up more lanes on its information highway, but you'll need a new phone to drive on them. The carrier has started to deploy LTE-U, which pipes LTE signals over unused 5GHz Wi-Fi channels to enhance capacity. The carrier's use of 20MHz of LTE-U makes it much easier for it to deploy gigabit LTE, which requires 50MHz of LTE spectrum. T-Mobile made the announcement today because the FCC approved LTE-U after a long tussle with the Wi-Fi alliance over LTE-U's coexistence with Wi-Fi. LTE-U will require new phones, though."
http://www.pcmag.com/news/351905/t-mobiles-next-speed-boost-requires-new-phones