I work in telecommunications. This is pretty much exactly correct.

Not really a rebuttal to anything you said, but to expand on the fact that WiFi calling uses VoLTE “most of the time”, which is true because in some conditions SIP is used, but if you are using an Android or iOS phone, you are always using a modem, the voice line is never analog, and all digital voice communications are sent over TCP/IP.

Currently, all phone calls made over a cellular network are monophonic, meaning audio is compressed into a single channel

This bit from the article is what I am trying to convey. Teamspeak doesn’t use whatever phones use when you make a phone call, even if it’s a cell phone. Cell phones do not have to do this. They have the bandwidth for stereo phone calls and yet, so far, they still compress it into garbage unless you’re using a VOIP app or Wifi calling on both ends.