Speech-to-Text engine for ad supported telephony

Ad supported telephony as a concept is not proven yet. But it is the new rage nonetheless. I think it is possible to build sustainable business model just because there are lots of talented people out there working hard to prove the concept. I am a strong believer in creating demand for a product where it may not exist.

One of the tools that could help drive ad supported telephony is a speech-to-text engine that converts the audio contents of a phone conversation into text in realtime, scans that text, picks keywords from the conversation, and requests an appropriate Google ad to be streamed over the phone client (let us say over a VoIP client).
I am impressed by how some of the sites like LinkedIn are able to frequently serve me with text ads that are so appropriate to my profile. I feel tempted to click. There must be very close integration between the information in your LinkedIn profile and the Google ad server. That is the kind of tight integration we require to make ad supported telephony a success.

So the idea being floated is something like a SpinVox speech technology + Google-API. The resultant app could be licensed to those telephony service providers who are looking to explore ad supported telephony. It could be integrated into the VoIP client a service provider is offering. So not only does the service provider have a tool that streams Google ads to its client, the provider also has a tool that is highly accurate and relevant in terms of the ads it should stream to the users.

Another possible business model is to simultaneously develop two apps: (1) the one I have just described above i.e. speech-to-text engine that interfaces with Google ad server, and (2) a Skype / SkypeOut application that simply ports over Skype capability to some web site but includes, in addition, the streaming of Google ads. You could then share the ad revenues with Skype. But the margins will be microscopic on SkypeOut calls.