[chedabob]

There are cellular network providers that specialise in IoT applications, where you pay monthly per device and data transferred. This is the first one from a search for "IoT Cellular": http://www.aeris.com/technology/aerconnect/

Particle run their own, but by the looks of it you have to use their Electron hardware: https://www.particle.io/cellular

If you could get people to install an app on their phone, you could use Bluetooth LE to passively collect the data as they walk past. There's a few asset tracking solutions that use this approach, such as Tile: http://www.wired.com/2013/08/tile-a-better-way-to-find-your-...

[at-fates-hands]

I'll throw this out there as well. . .

Windows 10 IoT OS is available too, which is built for something like this.

https://www.microsoft.com/en-us/WindowsForBusiness/windows-i...