Google developing 'ringback advertising' for Google Voice -- InformationWeek

Google has updated a patent application filed last year for "ringback advertising," a form of audio advertising that appears to be intended to work with the company's Google Voice service.

Audio ads, the patent application says, may unnecessarily annoy consumers. But providing audio ads during a time otherwise used to play a ringback tone may allow advertising without annoyance "because the consumer would have to otherwise listen to some other form of audio..."