Exactly how the advertising funnel works The earliest version of a sales channel that I'm able to find is this from 1904 by Frank Hutchinson Dukesmith, editor of the Salesmanship publication Below, Dukesmith introduced the idea of four phases that result in a sale: Focus, Interest, Desire and Conviction. Almost half a century later, a marketing as well as sales exec in the pharmaceutical sector, Arthur F Peterson, released the following picture in his publication, Drug Marketing, Describing, and Sales Training: