In older AT Command Interface Guide (like the one for FW 6.63), the values for AT+SPEAKER=value had the following meaning:
1 - MIC2/SPK2
2 - MIC2/SPK1
3 - MIC1/SPK2
4 - MIC1/SPK1
Since at least the version for FW 7.2a (I don’t have any between 6.63 and 7.2a archived) the AT Command Interface Guide changed this to:
1 - MIC1/SPK2
2 - MIC1/SPK1
3 - MIC2/SPK2
4 - MIC2/SPK1
The actual configuration is still following the old documentation though.
In our products we have primarily used MIC1 and SPK2, and if we were to follow the newer AT Guide, we wouldn’t get any sound through microphone due to incorrect documentation.