The EX90 Admin Guide states, that either a Headset or the Cisco TelePresence Table Microphone 20 can be connectet to the 3.5mm input on the rear.
These two microphone types are quiet different:
Headset: has a 3.5mm mono connector plug, asymmetric output and needs a PC-Soundcard-Style Power Supply.
CTS Mic: has a 3.5mm 4pin plug, symmetric output and needs a 12V Power Supply
Can anyone from Cisco tell us something about the technical backround, how the EX90 handles these two very different Microphone types?
And is there a way to use the Headset Mic only, but keep the output on the internal speakers?