If that's the case, you should be able to disable VoLTE to see if that is the issue, the phone will switch to 4G from 4G LTE as soon as you make a call. The option to do so should be in the dialer, go to settings, select Call, the Voice over LTE Settings and disable it there. See if it improves your battery life some how. I'm not having the Cell Standby issue, but I'm on a different phone.@Six8 @AppleRobert So, it seems AT&T variants dont suffer from the cell standby and TMO does... Could be something with Wifi Calling or VoLTE.
I have a TMO variant and as of late, battery hasn't been the same. But I'll continue to keep an eye on it,