Voice Quality on non stock ROMS topic

I was curious if others see that CM11/CM12 Roms have voice quality issues when compared to the stock rom. I am guess that VOLTE is not being used. Also I ran the GPE rom and it had good voice quality but b/c I have Sense firmware I had wifi issues.

Am I correct or do I need a different radio for CMxx ROMS?

thanks
-brad