The US Patent and Trademark office has awarded a patent for ringback tones (US Patent 7,006,608 B2), which “covers replacing the ring back signal with any acoustic sound presentation”.
The patent was filed by Karl Seelig, now CEO of Perceptive Impression (which bought into PromoTel to get the patent), and will be used to offer ringback advertising services…although I reckon that Perceptive Impression will be looking at getting something from the ringback tone services currently in use. Ringback tone services have been around for a couple of years, but the patent was filed back in June 2002. (via Ringtonia)
Related stories:
—Free Calls With Advertising Ring-Back Tones
—Ring-back Tones to Become Advertising Channel