Using ultrasounds as a side-channel is also used by Cisco's proximity sensors for telepresence units and the new Spark Boards. While on a call on my phone, I ca

Using ultrasounds as a side-channel is also used by Cisco's proximity sensors for telepresence units and the new Spark Boards. While on a call on my phone, I can walk into any conference room and swipe to handoff the video call from my phone to the room's telepresence unit, even if my phone is not on wifi (e.g. because I just walked into the building or had wifi turned off). In my experience, this flows much smoother than any wifi– or bluetooth–based pairing. https://www.cisco.com/c/en/us/products/collaboration-endpoints/spark-board/index.html https://www.cisco.com/c/en/us/products/collaboration-endpoin... Full disclaimer: I work in that BU.