I have been asked to look into the feasibility of sending notifications to mobile devices with in 5 or 10 meter radius of a booth at a trade show. The client would like to be able to send to notifications to passers by at a trade show and would like to alert them of their booth.
I am aware this is possible of users have the client's mobile application installed, but they would like to also reach those that do not.
Looking into the various options, bluetooth would require pairing (and the antenna to be on), NFC is too new and therefore not supported on many devices, and scanning wi-fi signals would let the client know people are around.
I am looking into foursquare and/or Brightkite API's, but that still requires those applications to be installed on the users' device.
Has any one tried this, and succeeded (technically and legally)?
You could use Bluetooth, the same way that some billboards broadcast to passers by e.g. http://www.newscientist.com/article/dn7883-billboards-beam-adverts-to-passing-cellphones.html