I turned it on once I got the phone and was able to make voice calls. I have updated the phone since then and mostly been on WiFi. Now when I need to make a call it won't work. I have tried everything thing to make volte appear again but it won't. I dialed *#*#4636#*#* volte provisioned is there but it won't toggle. My sim card uses volte in my Zenfone 3 and it did 3 weeks ago on this phone when I got it. All the 4g lte checker apps say congratulations your phone can use Volte. But I can't. Help please. I'm going crazy trying to figure this out.
If VoLTE was previously working properly and an update changed that, then it seems like some kind of software error. My recommendation would be to back up you data and factory reset the phone. If a reset doesn't restore VoLTE for you, we can log the phone to see what the error is.