My friend has a 7100g that he just bought used and the microphone output is way too loud. When he calls people it's crackily and you can hear everything around him. He called me and I turned my phone speaker all the way down and he still sounded way too loud.

Is there a way to adjust the microphone volume on this phone?

He took it to the cingular store and of course they had no clue.

Microphones were a major problem on the 7100 series devices. They are loud and overmodulate. Not much you can do except tell the user of the 7100g to move the mic away from his mouth a little bit and talk softer.