The patent was filed in January of 2008, significantly before the company acquired the VoIP service Gizmo5 in November 2009 and before it announced its Gizmo5-based, Google-branded VoIP service Call Phone, which was launched in August of 2010.
The ringback patent grants Google the (patent) right of placing audio ads in phone calls before a call is being answered or when a call is on hold. According to the document, the ad would be played in context with the caller's number. The advertiser would be charged based on a "listen-through" rate. The company noted that multiple ads could be played of the called party does not answer for some time.
At this time, Google does not include advertising in its Call Phone service, which is still guaranteed to be available free of charge for national landline and mobile calls. However, the technology of targeted audio advertising is certainly available to Google and may reach another dimension when it connects phone numbers available through Call Phone with users and their interests.
Google declined to comment on our question whether it had any plans to add audio advertising to Call Phone in the future.