Free phone service in exchange for ads. Telcos getting Google envy?

Katie Fehrenbacher over at GigaOm takes a look at Blyk as one of the emerging companies looking at providing free cell phone services in exchange for ads.
...many are convinced that the web-advertising model can be ported to the mobile world. (We think of it as telecos’ getting Google envy!)
With large companies chanting mobile advertising at every chance they get, it is hardly a surprise that investors are placing megamillion dollar bets on start-ups. Blyk is backed by private investors and Sofinnova Partners. Mobile ad startup AdMob took the CTIA opp to announce it had raised $15 million in fresh funding. Internet companies Yahoo and Google are trying to place their chips in the mobile advertising game, too. Yahoo announced at CTIA that it was expanding its mobile ad services.
This certainly looks like one of the most promising areas to be in for a startup if you have a fresh idea about how to present the right offer to the end users.