Verizon and AT&T often spar over network reliability, but the two biggest US carriers aren't opposed to helping one another out when the price is right. AT&T has completed a $1.9 billion purchase of unused spectrum from its primary rival, picking up 39 700MHz licenses that it says will help improve service to 42 million people across 18 states. Verizon Wireless also stands to gain from the deal; it's receiving valuable AWS spectrum in five western markets. As LTE smartphones continue to flood the smartphone market, both carriers have had to rethink their 4G deployment strategies. Verizon will likely use the AWS spectrum to complement its existing 700MHz holdings. The company has already snagged AWS resources from cable providers, a deal that by all accounts hinged on its agreement to offload spectrum to a chief competitor. The spectrum purchase was initially announced in January.