For those unfamiliar, Unlicensed Mobile Access (UMA) is a technology that allows you to make voice calls over WiFi using your real phone number (instead of making the call through a third-party VOiP program). The benefits are two fold: those with poor cell phone coverage can get clear calls wherever there is WiFi, and the minutes used over UMA don’t count against your contracted number of minutes. Also, many UMA devices seamlessly switch between UMA and GSM, so that if you need to leave an area with WiFi, your call will move onto the cell phone network. Only a small handful of devices of been able to take advantage of UMA, including the T-Mobile Shadow and BlackBerry Curve. It’s been a couple of years since we’ve seen a new UMA devices come around.

We just saw a purported slide of the LG Optimus One coming to T-Mobile as the LG Optimus with so-called WiFi-calling, which is probably just marketing-speak for the less widely known UMA terminology.

Well it seems that some other newer Android phones on T-Mobile will soon be getting UMA as well (referred to internally as “WiFi Calling Without Hand-Off”), if some screenshots of a T-Mobile training system are to be believed. What devices would qualify? By our estimation, most likely the Samsung Vibrant, HTC G2, and MyTouch 3G Slide — or perhaps to yet-to-launch MyTouch HD. Older devices like the Moto Cliq XT and Samsung Behold II may be left in the dust. Either way, WiFi calling can pave the way for a lower bill and clearer calls, so we’re excited.

Updated with more info about the rumored LG Optimus.

(via: TMoNews)