Dive summary: 

• According to Kantar Media, U.S. wireless providers dropped $5.3 billion on ad spend last year, and that number is expected to increase this year in efforts to switch reluctant customers. 
• The wireless market is saturated so all marketing is aimed at converting users rather than gaining; users' resistance to change is reflected in the fact that the top leaders Verizon and AT&T decreased ad spending but still remained in top spots with little change. 
• Sprint and T-Mobile will focus on their unlimited data plans which no other major carrier offers. 

From the article: 

"Verizon decreased its measured-media spend 10.7% to $1.19 billion last year from $1.34 billion in 2011. Still, it retained its position as the No. 1 U.S. wireless provider as market share fell slightly to 31.2% from 31.6%, according to ComScore. During that time AT&T's measured-media spend dropped 13.3% to $1.25 billion from $1.44 billion, but its market share rose a full percentage point to 27.3%. Sprint's market share was essentially flat at 15.7%, even as spending dropped 8.6%. T-Mobile upped measured spending 39.5% only to see its market share decrease to 11.6% from 12.7%."