Cool [Q] mic doesn't work during incoming call

Hi

I have a problem..
when I get incoming call, I'm muting the ringer and starts capturing audio streaming..
it works fine on most of the devices but not on HTC..
after reading in some forums I understood that in some firmwares, when we have incoming call,
the OS automatically direct the streaming into the audio chipset and the app does not have access to it.

first question:
is it true?
second:
how can i programmatically detect these problematic firmware..?

Thanks, Walid.