Proof of the Pudding?

So would you use the web to make a free call to someone in North America, in return for automated software searching your conversation to post "relevant" ads on the screen? Knowing what most teenages talk about on the phone, I'm not sure the content delivered would get past the firewall. Huge issue of trust here. Do you trust the pudding's privacy clause? They may not record the calls but do they keep IP addresses - in other words, who called who?