Features of Plantronics Headset Amplifiers

Question: What are the features on your standard Plantronics headset amplifiers such as the M10, M12 and M22?  I’ve misplaced my instructions. Answer:  Here are the features.  You’re looking at the amplifier in front of you.  The single RJ9 jack in front of the amplifier (marked with a headset symbol) should have the coiled “quick … Continued