Hello, I have the N7p now for 2 months, meanwhile with the Pie beta, and am actually satisfied with the device. Actually...
I use it in Germany, the model is TA-1046 with Android Pie (V390). My mobile operator is 1&1 in the o2 network.
o2 says VoLTE and (the more interesting one for me) WiFi calling is available for all users.
1&1 says it should work.
The N7p shows all four fields grayed out in the Phone-Information when entering the code *#*#4636#*#* (so it can't be activated manually). In the settings under 'Network & Internet' - 'Mobile network' - 'Advanced' nothing of VoLTE is selectable either. Under APNs 'o2 IMS' is displayed, but even that is not selectable.
And there is nothing about WiFi calling in the settings of the WLAN and/or the phone app.
I think one of them, 1&1 or o2, is cheating.
Or is it really possible that the N7p doesn't support these functions?