Yamaha has come up for a way for TV’s to interact your Smartphones, the technique, dubbed InfoSound, plays an inaudible (18 kHz or higher) signal over your TV’s audio track that can…..
be picked up by your smartphone’s mic and read with a custom app. It doesn’t use  high bandwidth, but even with a range of roughly 33 feet and a rate of 80 bps, this should be fine for transmitting a URL.
