The folks over at TmoNews have just confirmed that when the LG Nexus 4 goes on sale at T-Mobile stores in just a couple of weeks that it won't be coming with Wifi Calling (UMA) on board. Now this will come as no surprise to anyone who has followed previous Nexus phones in the past. The Nexus One, Nexus S and Galaxy Nexus all worked on T-Mobile's network just fine, but none of them were given official Wifi Calling support. Just because T-Mo is selling this one directly doesn't mean that changes now.
This may sound bad on the surface because many users would like the ability to have the battery life and call quality improvements that come with Wifi Calling, but this is actually a good thing. Not having the Wifi Calling app pre-installed on the Nexus 4 means that there's a really good chance it has the exact same firmware as the unlocked version coming from Google via the Play Store.
When it comes to updates and variants of Nexus devices, the fewer models that need to be supported, the better.
More: Google Nexus 4 Forums