4G LTE Codec sample rate

Hello,

I have been using 4G LTE and am not satisfied about the voice call quality.

I am using iPhone XR Max.

I would like to know: What codec sample rate the telco subscribers are using?

Video streaming’s audio quality is great as it’s streaming and using data, but I am not satisfied with the GSM voice quality.

Also: what codec sample rate the telco subscribers for 5G are using?