Neither? It's however the voice is encoded over the cell network. Again, I don't understand why because there's more than enough signal to stream digital audio. It's like they haven't upgraded voice quality in 30 years despite this being an obvious market advantage.
Hell, you can still rig a physical handset to work with bluetooth + cellphone and it'll guaranteed sound terrible.
As someone who had to make sure that call audio was properly processed on a phone I worked on to make it match today's standards, I can say without hesitation: it's all three.
The codec you get can vary from okay to terrible; the way mobile phones are built these days requires you to do echo cancellation; and the environment phones are used in requires you to do noise reduction.
Just disable audio processing on your phone, feed the network with raw microphone input and notice the complaints from your interlocutors. I've been there :)
> Neither? It's however the voice is encoded over the cell network. Again, I don't understand why because there's more than enough signal to stream digital audio.
Something's gone badly wrong in your memory; landline phones intentionally drop important vocal frequencies and automatically prevent everyone from sounding like themselves. Cell phones don't do that and have always had much, much, much better audio than landlines.
It's why 24.4 kbps is about the max you can get from a modem without your phone line being a fancy one. Compression (in the musical sense not the Information Theory sense, though they overlap)
Hell, you can still rig a physical handset to work with bluetooth + cellphone and it'll guaranteed sound terrible.
EDIT: phrasing, wording.