There is one incredibly important field of modern technology that has always proven to be a bit of an impenetrable enigma for ExtremeTech: The hardware used by mobile carriers. We know in general terms how a cell site works, but for the most part the actual hardware and software being used is a proprietary black box. That's why it's very exciting when a mobile carrier such as Sprint invites a tech blog to take a close look at one of its new LTE cell sites in San Francisco.