“Marketers don’t understand channels where you have to talk and listen at the same time. Like one of those maddening not-full-duplex speakerphones where you can’t interrupt somebody, this is what drives customers nuts. Think about it. None of those talking channels allows a response. None of those listening channels encourages actual feedback from the company.
The marketing industry’s idea of a two-way communication is to put an 800 number or a web address in an ad and take orders.”

Bernoff, J ~ Why marketers have trouble with full-duplex social technology (20.08.2009)