Just a little comment. I have seen many times the so called primary microphone error of the fairphone2 on the internet. I had the problem but it had nothing to do with the microphone but with the electric connection/module to the display module. If you have this problem you can check whether the mic works fine if you press tightly together the phone around the microphone module (just call another phone and try it). If this helps, there is a good chance that the true reason are worn out plastic parts around. I fixed it by putting a millimeter of tape underneath the microphone module and before screwing it on again. Now the module gets pressed a little bit against the display module and works just fine again (for the moment). Probably the little worn out outer shell was a part of the problem, I did not have a new one, but could imagine that buying a new outer shell for the fairphone2 might rather solve the problem than changing the microphone module. Just try it yourself before ordering a new microphone.