Why the MIC not working?

[tony_lth]

Hi, All,

I designed a GSM station, and it works fine, but when I tested audio, I found I can hear the other terminal, but the other terminal can't hear me.
I used PHILIPS SMH1000 MIC, I don't know it is a stereo MIC or a diff MIC, I supposed it a diff MIC.
And my audio amp circuit is diff.

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Is the MIC+/MIC- can be freely linked to the aforesaid audio amp input P/N?
Is it ok that MIC+ linked to input_N and MIC- linked to input_P?

 

[tony_lth]

I know why the MIC can't work, because I didn't bias it.