Sprint Nextel (NYSE:S) said it became the city of Houston's wireless service provider, taking over for AT&T, which had been Houston's service provider for decades. Sprint said that under the deal--which it believes will be worth $15 million over five years--it will furnish cellphones and data services for the majority of the city's departments. The deal includes more than 6,000 wireless devices and 10,000 wireless service activations, the company said. Article