Sprint, T-Mobile to Spend Big in Pursuit of Verizon, AT&T

US wireless customers are proving to be a stubborn bunch when it comes to changing providers. But that's not stopping carriers from pumping big bucks into advertising in hopes of grabbing market share.

Wireless is one of the country's big-spending ad categories -- carriers collectively dropped $5.3 billion on measured media last year, according to Kantar Media. Analysts expect T-Mobile and Sprint to increase ad spending to persuade consumers to switch from the long-time industry leaders. T-Mobile has adopted a combative message under CEO John Legere, aggressively advertising itself against AT&T specifically. Sprint Nextel shareholders recently approved an acquisition offer from Japan-based mobile provider SoftBank, giving it the deep pockets needed to contend with AT&T and Verizon. Buying market share isn't a surefire strategy.