I need to detect if a wifi network that lacks any WPA or WEP protection is actually a usable wifi hotspot with internet access. In other words I need to discern between standard free hotspots and things like T-mobile hotspots which are unsecured networks but require logging in via a browser window.
I thought about sending a ping to our servers and checking the response, but if the ping was successful how do know for sure that they haven't just logged in already (e.g. in this scenario if they had a T-mobile account and previously logged in).
Its an android app if that matters.