I've not seen a PC without an audio codec since the early '90's. I've never seen a cellphone without one. Just what did you think that "chip" on the audio circuit is?
neither have I, but AGAIN you circumvent the issue.
There is no serial access to the codec from the outside, so what the #&!! does that have to do with serial comm of any kinds from a uC?

Mode 0 has nothing specific to do with a cellphone, except that the failure of the deisngers to use it and to use the extremely inefficient async protocol instead may indicate why cellphones are so unreliable.
So, now, in your opinion, the fact that the cellphone designers chose to not require a redesign of the PCs interface to the outside world is WRONG?

I have reread your last babble and what you, in fact state is

"The cellphone people made a mistake when they made thair interface PC compatible" WHAT TOTAL DRIVEL

Erik