After previously seeing the upcoming Nexus 4 on T-Mobile will likely not have WiFi calling, it appears that it will after all. T-Mobile Support recently outlined the full data features of the devices and lo and behold– full WiFi calling is indeed supported. All that’s needed is for T-Mo customers to get a specialized GBA SIM card, register a 9-1-1 address and turn on the phone’s WiFi and connect to a WiFi network. All in all— while the pricing of the device is somewhat absurd on-contract, at least T-Mo customers will be able to save many of those precious monthly talk minutes which is a good thing, right?
source: T-Mobile Support