That's nice...but I actually disabled the wifi calling as it didn't play nice with cell towers. Been a T-Mobile customer since 5s came out, but needed a phone and 5s supply issue, so got the LG2 on the JUMP program with $0 up front that would never see again, vs $99 for the 5c. Plan to JUMP to the 6.
Issues related to WIFi. 1) Out of range warning when walked to kitchen or in the yard, until added extender, 2) No hand-off from WiFi to cell tower when leaving the area - crackling sound and dropped call, and 3) Don't know if considered inactivity on the network system, but dropped calls after approx. every 5 minutes on long conversations/hold times (i.e. tech support conversations) when sitting in the same room with the WiFi router. Turned the WiFi off, forcing it to use the T-Mobile cell tower 3/4 miles down the road and no problems.
Since the LG2 also functions as a hotspot to power the my iPad, with that option, T-Mobile required unlimited data. I don't care if I use 4G data off the cell tower as there is no reason to conserve it with WiFi. Unfortunately, their free International data and text DOES NOT include personal hotspot when utilizing the foreign carrier, so I can't power the iPad independent of a restaurant or hotel providing free WiFi, however, the travel and translation apps on the iPad will transfer to the iPhone and will be powered by the foreign carrier's wifi for free. Very timely since leaving early October for 2 weeks.