Some carriers allow you to make phone calls over the VoLTE/4G network dramatically increasing the sound quality compared to traditional phone calls.
Activate on an iPhone device
1
Go to ""Settings → Cellular → Cellular Data Options → Voice & Data""
2
Ensure ""LTE"" is selected and then activate ""VoLTE""
Activate on an Android device
1
Go to ""Settings → Network & Internet → Call Settings""
2
Tap to enable VoLTE/HD Voice/Enhanced calling