Did you read those docs?

> Note: You may need to increase your iPhone volume, since Dash Button uses ultrasonic tones to sync with your iPhone during setup. If prompted, drag the volume slider to the recommended level, at or above where it says Best.

Ultrasonic tone sync?

I actually wrote a library that does this, FSK to WAV and back is just a few lines of code, and fairly reliable. There are even Javascript libraries that can do it.

I think it probably is real, it just shouldn't be. :-/

Isn't that what Clinkle was supposed to be using? It was supposed to be the hot new tech that could replace NFC. Or something or other...

[1] http://www.thewire.com/technology/2013/07/what-is-clinkle/66...

That's actually pretty established technology nowadays. I'm not surprised they're using it.

Ultrasonic communication is also used by some of the 2nd screen tv apps.

Doesn't the Chromecast have that capability?