[ItsMichaelNotMike]

There are dual mics, where indicated.

When in "conference room" mode, the mic on the side kicks in. When talking as a regular phone, the mic at the bottom is the only one that works. This makes sense since the mic on the side cannot be on when talking in "regular mode." Can you imagine the noise from wind, etc.

Leave the setting on automatic as this will also adjust the duplex mode feature too.