Yesterday, we saw that LG's Optimus One might ship with WiFi calling , and that's all well and good, but a new leak suggests the Optimus was just the tip of a UMA iceberg to come. The above picture is one of several allegedly leaked training slides obtained by TmoNews, highlighting a dedicated "Wi-Fi Calling" app that may come pre-installed on upcoming Android devices, one of which just might be that new T-Mobile G2 . Before you raid your piggybank in hopes of free VoIP calls, however, know that this app-ified brand of WiFi calling isn't necessarily the seamless switching solution we've wanted all along ; that little yellow "limitations" tab reportedly explains that as soon as you leave the WiFi radius, you effectively drop your call.