You ask for it, you get it. In principle, voice is the ultimate no-brainer interface – and a perfect fit with a slew of information and content services ranging from directory assistance to mobile search. The Wall Street Journal has picked up on this trend and provides a worthwhile over view of the players and services to watch.

Indeed, the flurry of activity in the space –marked by mega-deals such as Microsoft’s recent purchase of TellMe and Nuance’s acquisition of VoiceSignal – underline the pivotal position of voice in the mobile search services mix. However, the interest is voice recognition isn’t just another love affair with technology; it’s “part of a broader gold rush taking place by major Internet companies for new advertising technologies.” Against this backdrop, the new model is about giving out information for free and trying to make money off advertising. As Emerick Woods, CEO of V-Enable, a provider of search and directory-assistance solutions, is quoted as saying: “There is no question that these services have got to be free. Anyone who thinks otherwise is fooling themselves.” Operators need little convincing. Jeff Kunins, vice president marketing at Tellme Networks claims: “All operators are exploring the possibility of setting up free services.” That’s bad news for the paid directory-service business. The article refers to new research from Opus, which estimates revenues will drop from $3.5 billion in 2006 to $1.8 billion by 2010. Opus predicts the advertiser-supported free model for directory services will increase to a $3 billion business in 2010 from $203 million in 2006.

Little wonder the usual suspects – and then some – are exploring voice + advertising schemes. Medio Systems enables voice search and advertising on the Verizon portal, Microsoft’s Tellme service runs ads after some of the searches are performed and Google’s voice search service in test-mode and (so far) free of advertising. The company declined to say whether running ads was on the roadmap. “We think about monetizing our products later [after the testing is complete], if it makes sense to the user,” Bill Byrne, senior voice-interface engineer at Google, was quoted as saying. (Another reason for the run on directory services is money. Senior execs at several voice technology companies have confided they are retreating from their efforts to provide a voice interface to content-selling services. The margins are low and the tension is high since it’s tough to put a price tag on the value voice search brings to the table. The cut a voice company should get from a sale of ringtone is an open question and some companies are losing patience waiting for an answer.)