Speaking at IAB Engage in London, Gregory, former head of ad-funded mobile phone service Blyk, said the emergence of mobile media measurement meant brands could focus more on promotion.
He said: "The year of the mobile was two years ago when the iPhone was developed. It has generated a third of smartphone traffic worldwide. Brands need to think about how to drive and promote apps and not just develop them.
"Brands need to go beyond the banner appeal of different formats with rich messaging leading the way. A third of consumers just want to see interesting information on their phone."
Gregory added that mobile was the next big media opportunity for brands, due to its reach. However, he warned brands needed to develop ad offerings beyond simple banner ads for mobile.
He said: "Mobile has reach with a unique personalisation opportunity. It has a unique ability to target consumers. It's truly accountable on a personal level. Mobile is the next opportunity for brands, as it drives customers to profile themselves - that develops a rich opportunity for brands."