I have a multiple input TOA A-903A mixer/ampifier. We use Cartioid
Dynamic 600 ohm mics. Is it possible to replace one with an over the
ear cell phone headset with a "boom" mic?

Any idea if this would be a balanced or unbalanced connection?

Purpose would be to have the mic right by my mouth, and not have to
hold the heavy mic or have the heavy mic in a holder and have to lean
over to it. Specifically I want to use it this way as the caller for
Bingo games.

the mic connection, I believe, is:
,-------------------earth
O O ------------common
O -------------hot

additional info: I measured across the mic with standard DVM - reads
approx 900 ohms.