Sprint and T-Mobile know they can’t just stand idly by like they did in the 2008 when both Verizon and ATT cleaned house in the hugely important 700MHz spectrum auction that gave America’s top two wireless carriers a big advantage in building high-speed LTE networks. Now The Wall Street Journal reports that Sprint and T-Mobile are joining forces to together raise $10 billion to spend on spectrum holdings in the the upcoming 600MHz auction. This will be a hugely important auction for both T-Mobile and Sprint, which have been at a persistent disadvantage compared with Verizon and ATT because they’ve lacked access to contiguous chunks of low-frequency spectrum that you need to build a top-notch nationwide mobile data network. Winning big in