Carriers spend millions of dollars each year promoting their brands through commercials, advertisements, events and other promotions. How effective are they? Marketing consultancy Millward Brown revealed the results of its fifth annual ranking of the world's most powerful and valuable brands--the BrandZ Top100. According to the group, there are 13 mobile operators in the top 100 ranking this year. China Mobile remains the most valuable global mobile operator, with a brand value of $52.6 billion, and is No. 8 in the overall ranking. Verizon Wireless (NYSE: VZ) is the third-ranked brand, and increased its brand value by 39 percent compared with last year. AT&T Mobility (NYSE: T) is right behind at No. 4, and increased its brand value by 18 percent. How did the other operators stack up? Special feature
