It depends on what you mean by "ultrasonically". You can quite easily send and recieve 19 khz tone using ordinary 44.1khz equipment, and virtually nobody is going to hear it.
Young folks and dogs would probably be annoyed. I could hear up to about 19k into my 20s. So, depending on your use case, it might not be workable. I also used to get headaches and my ears would feel fatigued from a CRT monitor that squealed at a frequency I couldn't "hear" (but could detect by other means), so I suspect those frequencies do interact with our ears and brains in ways that we can't "hear" in the usual sense. (Though I also know that there's a lot of woo around this issue in audiophile circles...I think anything beyond about 22k can be considered safely out of range of human hearing. Our ears just don't have receivers for those frequencies.)
I'm trying to think of use cases for ultrasonic data transmission, and they're mostly nefarious. Traversing an air gap, for instance. Higher frequencies are difficult to transmit over distances and through walls, so you'd need to get your receiver into the same room or make it a very high SPL.
I have a wifi camera that uses bleeps and whistles and warbles from a phone or tablet to configure itself before it gets on the network, which is pretty neat but seems weird in a modern world. But, I guess that's something that could be done ultrasonically to make it seem more like magic. But, since it is already pretty error-prone, I would bet pushing tablets and phones (including crappy ones) to accurately produce very high frequencies at a volume sufficient to program a nearby device wouldn't be worth the added magicalness.
I'm trying to think of use cases for ultrasonic data transmission, and they're mostly nefarious. Traversing an air gap, for instance. Higher frequencies are difficult to transmit over distances and through walls, so you'd need to get your receiver into the same room or make it a very high SPL.
I have a wifi camera that uses bleeps and whistles and warbles from a phone or tablet to configure itself before it gets on the network, which is pretty neat but seems weird in a modern world. But, I guess that's something that could be done ultrasonically to make it seem more like magic. But, since it is already pretty error-prone, I would bet pushing tablets and phones (including crappy ones) to accurately produce very high frequencies at a volume sufficient to program a nearby device wouldn't be worth the added magicalness.