There is an alternative. If the device is in user where there is already a router, the device could sign on to the local network.
There are quite a few Service Discovery Protocols and various flavors of ZeroConf (Bonjour) in wide use these days so it's pretty much a solved problem if your device has the horsepower to run the protocols.Still doesn't change the fact that this is not an application that should require an app :-)
Do these services mean that the user can type "DartBoard" or something like that into a browser address? Does something need to be installed on the client device first?