[LG V40 Questions & Answers] wantpizza:
Visiting the US and trying to find more information on this upcoming 3G shutdown.

From what I have learned from calling/chatting with T-mobile, AT&T, Sprint, Mint Mobile, Boost Mobile, Straight Talk and Consumer Cellular (** all this info is not guaranteed completely accurate as not all cell tech support people actually know everything - not a knock - how could they know everything about 1000 different handsets just saying)

Following anything you see below is certainly without warranty. I am not responsible for bricking your phone or turning it into a coffee maker.

Okay so enough disclaimer. Here is what I think I have learned:

For reference my phone is a V40 ThinQ LM-V405UA. It was manufactured for Sprint - bought it unlocked and refurbished.

AT&T has already shutdown 3G calling and all voice calls are now on VoLTE... but maybe not in all areas??

T-Mobile and it's MVNO's still have 3G operating and plan to shut it down in July.. ish...

Mint Mobile and Boost shows my IMEI to be compatible.

Consumer Cellular show my IMEI to NOT be compatible.

The AT&T store told me in person that I would NOT be able to enable VoLTE on my phone with the network since it was made for Sprint

AT&T Chat - escalated to Technical Support - confirmed that there was no way to enable VoLTE and that it would not function on their network.

Chatted with T-Mobile, Sprint and LG - they could not tell me any service codes or techniques to enable VoLTE. Each did kindly tell me I should check with LG, T-Mobile, Sprint...

*#*#4636#*#* brings up the Testing Menu

Under Phone Info you can switch on "VoLTE Provisioned"... (YES!! - right? ...not sure this does anything)

Below that is a toggle for "Wifi Calling Provisioned" . Mine is grey'd out in the off position

You can set the preferred network type - and mine is set currently to LTE/CDMA/UMTS auto (PRL) - not sure what that means but...

You can enter the "HiddenMenu" by dialing *#546368#*405#

I clicked all around and found only one thing

Click SVC Menu

Scroll down to VoWiFi (Ahaaa!! right??)

Click on Wi-Fi Calling Toggle and change the value to 1 - on

I rebooted and... no change.

I currently have a Mint Mobile sim (T-Mobile towers) and it currently works. Gleaning from what I read somewhere - if you truly have VoLTE activated and configure correctly you should be able to have data to load a web page DURING a call (with WiFi switched off). Mine fails to load during a call.

If you have VoWifi configured and activated correctly you should be able to make a phone call having Cell data switched off and attached to WiFi. Mine can not make a call.

My wife's Xioami phone does all of this and even has little VoLTE symbols at the top of the screen.

Hopefully all of this information helps someone else - but even better yet - hopefully someone can tell me if I will still have cell service in July when T-Mobile is shutting down their 3G service. Are there other tests I should be doing?

Also for fun - pulled my LG-V20 from the drawer and messing with it. It shows that WiFi Calling is WORKING... Battery is bloated but I think I had a successful test with it.

Anyway - that is where I am at. All tips, tricks and ANSWERS are appreciated.