The FP2 has a standard 3.5 mm headphone/mic/headset jack. If something gets plugged in there, the internal speakers (both phone speaker and rear speaker) are shut off.
Now there can be conditions in which the main microphone in the bottom module gets defective and can’t be replaced AND wearing a headset is impractical.
There are microphones that can be plugged in the jack and that work well, but this shuts off both speakers, so normal calls and speaker calls won’t really work.
The jack is in the upper module, as is the phone speaker. But the main (rear) speaker is in the bottom module, so it could (!) be that inserting something into the jack does not cause a mechanical switch (in the jack) to disconnect at least the rear speaker, and this could (!) be in software.
Is there a way to circumvent this and re-activate at least the rear speaker even if something is plugged in?
I believe that the shut-off of the speakers is done in software, as it takes approx. 0.5 - 1 second to active. A mechanical switch inside the jack would immediately shut off the speakers, but the delay can only mean that it is in software, and thus could be circumvented somehow…
Oh, I forgot to mention that I’m using Fairphone Open OS.
Deep inside there must be a register or config setting where to direct audio to.
Interesting side note: When I connect a USB audio interface, like the USB adapter from Jabra (using an OTG adapter) I get audio from the phone on the headset hooked up to the Jabra adapter. I get music. But I do not get audio from phone calls, and the microphone won’t work. When I plug that very same headset directly into the Fairphone 2, I do get call audio AND the microphone works (and the internals are shut out).
And: The volume controls on the Jabra adapter do work! They direct the volume setting of the FP up or down (setting immediately appears on the screen). So the correct USB profile does get applied (although no headset icon apears in the status bar as it happens when I connect the FP to my Toyota car, which uses a headset profile, that works like a charm).
This means that something inside FPOOS directs call audio in- and output always towards/from the internal speaker/mic, unless something gets plugged in - then everything goes there. But music can be directed anywhere. This confirms me in my belief that this is all software (OS) controlled and not HW…