Just completed an experiment. Raspberry pi3 kit. Loaded mumble server on it. Modified the wifi settings so the pi is now it's own wireless router with wpa2 security. It works dandy with the phone app. It starts just by plugging in the power. No monitor, no keyboard. Just power supply and the pi in it's case ... about the size of a deck of cards. Stand alone system, no internet connection needed or desired. Range on the wifi looks good so far. From my bunker/basement to the second floor of my house with no dropout. Am going to test in the theater this weekend for range and coverage. I do have the option of testing an external antenna version if range is a problem. Would add 15 to 20 bucks to the cost. Can be done on the pi zerow as well.. I will probably test this as well... which literally can give a school or community theater full duplex, low latency via wifi and phone app. for 25 to 30 bucks.. if range is a problem, wifi repeaters could be used in theory. Stay tuned. If there is interest out there, I could probably burn the microsd cards and send them to interested parties to plug in to the pi of their choice for the cost of the sd card and a few bucks for the burn and postage. Disclaimer.. the sd is theoretically vulnerable to corruption in an uncoordinated power down.. since we are not using keyboard/monitor. I've had this thing up and down lots of times now without incident.. but insurance would be keeping a second sd card handy and ready to plug in if need be.