Simply a Beacon.
When the Android / IOS  / Windows Devices  are ‘Bluetooth & Locations Enabled via the Android / IOS / Windows, identifies that there’s a beacon nearby ( within 150 feet to 400 Feet – your digital billboard – your  Proximity Beacon Unit – Depending on your results , some units will perform differently ).
The Beacon grabs that information and it puts a notification on the Android phones within the 400 Feet  range. That’s how people have the ability to view your broadcast!
(NOTE: And it is 400 feet or less depending on unit. I tested it myself. So, don’t let anyone try to convince you it’s less than that.)
So, it’s the PHONE that actually reaches out to get the information. It is NOT Proximity Beacon ‘sending’ a message to Android phones!

Again, we do not ‘send’ that information to the Android / IOS / Windows Devices !

So, do not tell people that we send messages to Android/ IOS/ Windows Device because that’s NOT the truth, nor how this works.
People must enable their ‘Bluetooth and Location Services’ on their Android / IOS / Windows device before they can access it, A notification lets them know whenever an app, beacon or website is available, and tapping it will take them “straight into the intended experience.” If the recipient is not interested, they can just swipe it away, just like any other notification.

The moment ANYONE turns on bluetooth and locations on their Android / IOS / Windows Device, they are giving access to their phone to notify them of any and all nearby digital billboards that come into the range of their Android / IOS / Windows Device, this may take upto 30 seconds for the notification to show up.

The only question that remains is, do you have your own digital billboard? I do. It’s called “Genusity”