A leaked internal document suggests T-Mobile may be bringing a UMA-like feature to its Android handsets. For those not familiar with UMA, it is a feature found on T-Mobile’s handsets that allows a user to place a VoIP call via WiFi when cellular service is not available. UMA lets you use your T-Mobile number to place the call, instead of a third-party service like Skype which forces you to use an alternative number.
This leaked training document does not mention UMA, per se, but it does detail a new Wi-Fi calling application that can be used to makes calls without adding onto to your current calling plan. The document does not name which Android handsets will launch with this application but both the T-Mobile G2 and the LG Optimus are potential candidates. The G2 was spotted with an icon that resembles the icon in the above training documents. Similarly, a leaked document for the Optimus One singles out Wi-Fi-based calling as a salient feature of this handset.
While the debut of UMA on T-Mobile’s Android offering may cause many to rejoice, it could launch with a few important limitations including no support for UMA to GSM handoff. If you are talking on the phone via WiFi and lose your connection, your phone will not automatically switch to an available cellular signal. Once you drop your WiFi connection, your call will drop, too.
One other potential buzz kill is the suggestion that this WiFi calling feature will land on select Android devices only. If a handset does not launch with the application, it still could be added via an over-the-air update but we have no concrete list of list of which Android handset will or will not receive the WiFi calling feature. Fingers crossed that WiFi calling makes its official debut first on the G2 and then on the Optimus One.