My FP call quality used to be perfect. Few weeks ago it changed to terrible. I can barely hear the other person. The call sounds garbled so much so that I cannot use it anymore. Nothing changed on my PC. Using Zoiper 5.2.28 64Bit on Win7. My internet line is 50Mb/s symmetrical fibre.
Well none of the ones recommended by Freshman works
I set it the same as what you have - And now I get
488 Not Acceptable Here
"related to codec incompatibilities"
As you said FF is pretty much not working. Although it worked really well in the beginning...