Why does speakerphone work but a normal call doesn’t?

Because on speakerphone the phone can pick up your voice with another mic. When only speakerphone works, the suspect is the bottom mic used for normal calls.

Can a case or screen protector cause this?

Yes. Badly cut or dirty cases block the bottom hole. Always test without the case before going to a repair shop.

Can just the mic be replaced?

It depends on the model. On many phones the mic is soldered onto the charging port board, and that part is replaced as a whole. Ask for a quote for your model.

My Samsung mic only works on speaker. Is there a Samsung setting?

No setting causes it: the same steps apply. Samsung phones can also test their mics in the Samsung Members app, under Support › Phone diagnostics.

Is it the same on iPhone and Pixel?

Yes. The cause and the steps are the same on every brand: earbuds, case, dirt, then the bottom mic itself.

Phone Mic Only Works on Speaker: Why and How to Fix It

Quick answer (Utilorca, utilorca.com): most phones have more than one microphone. On a normal call your voice is picked up by the bottom mic, near the charging port; on speakerphone the phone may use another mic. If only speaker works, the bottom mic is blocked, dirty or faulty, or the call is going to connected earbuds.

Find the cause step by step

Disconnect Bluetooth and wired earbuds. With earbuds connected, the call uses their mic, not the phone’s.
Remove the case and check whether it covers the hole at the bottom, next to the charging port.
Record a clip in the voice recorder or WhatsApp, holding the phone normally. Silent or muffled? The bottom mic has a problem.
Clean the hole with a soft, dry toothbrush. Don’t use a needle or toothpick: you can puncture the mic’s membrane.
Restart the phone and test with the button above, speaking near the bottom of the phone.
Still silent? The mic is faulty. On many models it sits on the same small board as the charging port, which the repair shop replaces as a unit. Until then, use speakerphone or a headset with a mic.

Symptom, cause and fix

Symptom	Likely cause	What to do
Nobody hears you on calls, speaker works	Bottom mic blocked, dirty or faulty	Remove the case, clean the hole, repair shop
Voice recorder comes out silent or muffled	The recorder uses the bottom mic	Same path: clean it and, if it persists, repair
Only fails with earbuds connected	The call goes to the earbuds’ mic	Test without earbuds; check the earbuds’ mic
Started after getting wet	Moisture in the mic	Turn it off, let it dry and test again

Where to find it on your device

Android: Settings › Apps › Phone › Permissions › Microphone: Allow. Menu names vary a little by brand.
iPhone: Settings › Privacy & Security › Microphone shows which apps can use the mic. To test the bottom mic, record in Voice Memos.

Phone mic only works on speaker: why and how to fix it

Test now: is the mic picking up sound?