Very strange mic problem

[AC Question]

The mic works just fine in all cases except on network calls.

Ok google is as responsive as always and works perfectly. The mic test works properly. VoIP calling works perfectly too. Only when i make/receive a call through my carrier, i can hear the other person fine, but they cant hear a word. like completely nothing.

I'm very puzzled as to why this has happened.

any help would be appreciated.