Microphone is not working, speaker is working

I changed the rear case for an iPhone 5 and after I reassembled the phone back, I noticed the following facts regarding the microphones:

- I can be heard when talking to Siri (Siri is able to hear me without any issues)

- I can be heard during calls if I switch it to Speaker (the receiver of the call is able to hear me without any issues)

however:

- I cannot be heard during calls when speaking on the "normal" microphone.

- I cannot be heard during calls when speaking through the headphone's microphone.

I already replaced the original Lightning Connector and Speaker Assembly with a new one, thinking that the old one might have been damaged, but the issue still persists and I cannot be heard during calls.