Where is the microphone in a 12 Tahoe?

[afishinado]

Trying to figure out where the microphone is in my Tahoe. I think it is the roof directly above my head, but not sure. I have tapped on it (and every other spot that looked like it could be) with someone listening on the phone, no help. I have had everyone tell me the phone sounds terrible

 

[BlessedHellRide]

You having issues, there is a tsb on the clarity of call from receivers end.

 

[afishinado]

You having issues, there is a tsb on the clarity of call from receivers end.

Wat is a tsb? Technical Service Bulletin?