I've been trying to figure out how to achieve the best audio quality in phone calls, and part of it is finding out whether GSM, CDMA, LTE or other standards/technologies compress the audio the same way or differently depending on the phone's settings or hardware. I'm not asking about internet audio calls (like using Skype for example) but regular built-in phone calls.
Does the available network type determine the audio quality of phone calls? Can I improve the sound quality if I get a phone from a GSM or CDMA carrier? Does LTE or some other more modern standard improve audio quality significantly?