Telex MCE325 - Manual (Page 32)

2-12 C S I - 2 0 0 U s e r I n s t r u c t i o n s
Carbon-microphone headset connector: ¼-inch, tip-ring-sleeve phone jack.
Table 2.9 Carbon-microphone headset connector.
SECTION FUNCTION
Tip Carbon microphone
Ring Headphone
Sleeve Common/ground