Consumer brands are not realising the full potential of mobile as an advertising medium and agencies now have a critical role to play in preaching its benefits, admits Michael Roth, chairman and CEO of advertising agency giant IPG, in a new interview with Mobile World Live. “It’s growing, there’s no question that the spend is growing, but certainly not at the rate that the device universe is growing, and that’s an area that we have to do better,” Roth comments.