Why is call volume low when music and video are perfectly loud?

Because call volume is a separate level that you can only set while you are actually on a call. Press the volume buttons during a call — that adjusts the call level, not the media level, and the two are stored independently. If call volume is already at maximum, the next suspects are a blocked earpiece opening and Phone Noise Cancellation, both covered below.

People cannot hear me on normal calls but can on speakerphone. What does that mean?

It means the two modes use different microphones, and that narrows the fault down a lot. A normal call held to your ear uses the microphone on the bottom edge, next to the charging port. Speakerphone switches to a different microphone in the array. If only one mode fails, the problem is that specific microphone or its opening — not the phone's microphone in general.

Call audio keeps jumping to my Bluetooth earbuds when I do not want it to.

Bluetooth wins the routing contest by default: once a device is connected it takes the call audio unless you actively move it back. During a call, tap the audio route control on the call screen and select iPhone. To stop it permanently, go to Settings → Bluetooth, tap the device and choose Forget This Device — simply disconnecting only lasts until it reconnects.

iPhone Call Audio Problems: Quiet, Muted, or Going to the Wrong Device

Short answer: "my iPhone call audio is broken" is really three unrelated problems wearing one name, and the first move is to work out which one you have. If *you* cannot hear *them*, the fault is on your output path. If *they* cannot hear *you*, it is your microphone. If the sound is coming out somewhere else entirely, it is a routing problem — and Bluetooth causes most of those.

Work out which side is broken first

Everything gets much easier once you know which of these you are looking at. The useful question is not "what is wrong with my phone" but "who is missing what".

What you notice	What it actually is	Where to look
You can barely hear them	Your output path	Call volume, blocked earpiece opening, or audio routed to another device
They cannot hear you	Your microphone	Bottom mic blocked by a case, lint or a finger; the wrong mic in use
Sound comes out of the wrong place	Routing	A connected Bluetooth device, or a car system that grabbed it
It is only bad inside one app	That app's audio session	App-specific — not a phone-wide fault
Crackling, dropping, cutting in and out	Signal or a failing component	Network quality, or genuine hardware

Notice what is *not* on that list: "the speaker is broken". That is the conclusion people jump to, and it is usually wrong.

If they cannot hear you, run the speakerphone test

This is the highest-value diagnostic in the article. Make a normal call with the phone held to your ear and ask whether they can hear you. Then switch to speakerphone and ask the same question.

Fails only in normal calls — the microphone on the bottom edge, next to the charging port, is the problem. That is the one used when the phone is held to your ear.
Fails only on speakerphone — a different microphone in the array is at fault.
Fails in both — either something is covering the phone broadly, or you are looking at a real hardware fault.

iPhone does not have "a microphone", it has several: the bottom edge, the front near the earpiece, and the rear near the camera. Which one is live depends on how you are holding the phone — earpiece call, speakerphone, video recording, or rear camera. "The microphone is broken" is almost never the right description. "This microphone, in this mode, is blocked" usually is.

Then check the obvious obstructions, in this order:

A case or holder wrapping the bottom edge. Many cases leave a narrow slot that fills with pocket lint. Take the case off and repeat the test — this costs nothing and resolves a surprising share of cases.
How you hold the phone. A finger resting across the bottom edge is a common cause and completely invisible to you while it happens.
Lint in the opening. The bottom microphone shares its region with the charging port, which is exactly where pocket lint compacts. Clear it with a soft dry brush and a wooden toothpick held at a low angle. Never use metal, and never push liquid into the opening.
A misaligned screen protector covering the top microphone on models that have one near the earpiece.

If every mode fails with the case off and the openings clean, stop troubleshooting. That is hardware, and it is worth having inspected rather than worked around.

If you cannot hear them

Start with the level, because it is the most common cause and the easiest to rule out: call volume is a separate setting from media volume. Pressing the volume buttons while music is playing changes the media level, which does nothing for calls. You have to press them *during a call* to move the call level. This single misunderstanding accounts for a lot of "my earpiece is broken" reports.

If the level is already at maximum, look at these:

A blocked earpiece opening. The earpiece slot at the top of the screen collects the same debris as the bottom port. If calls sound muffled and slightly distant rather than silent, this is the likely reason.
Phone Noise Cancellation. At Settings → Accessibility → Audio & Visual, this reduces ambient noise on the earpiece. It usually helps in a noisy room, but on some calls it makes the other party sound thin or faint. Turning it off is a one-line test.
Headphone safety limits. Settings → Sounds & Haptics → Headphone Safety can cap output volume. It is aimed at headphones, but it is worth knowing it exists if audio is quietly limited everywhere.
A Bluetooth device with its own volume. The phone's volume control and the accessory's volume control are different. A headset turned down at its own end will still show full volume on screen.

Why calls are the only thing affected

People find this contradiction suspicious — "music is fine, so the speaker must be fine, so why are calls bad?" — but it is expected behaviour, not evidence of a fault.

Calls and media do not travel the same path:

Different output by default. Media plays through the loudspeaker. A call plays through the earpiece, which is a small, deliberately quiet driver at the top of the screen.
Different Bluetooth profiles. Music uses A2DP; calls use the hands-free profile. A headset can handle one and handle the other badly — or not at all. That is why "my earbuds are perfect for music but terrible on calls" is a real and common report rather than user error.
Different microphone, with different processing. Call audio runs through beam-forming and noise suppression aimed at a voice held close to the phone. Media recording does not.
Extra processing on top. During a call you can also choose a microphone mode from Control Center (Mic Mode): Voice Isolation prioritises your voice over background noise, Wide Spectrum passes more of the room through, and Standard is automatic. This changes what the other person hears, not what you hear — which is a frequent source of confusion when someone reports that "calls sound bad" without saying which end is bad.

So the correct reading of "media fine, calls broken" is not "contradiction". It is "the paths are different, and the problem is in the call path".

Things that are usually not the problem

"The earpiece is dead." Far more often it is routing or a blocked opening than a failed driver. Rule out the free explanations before paying for repair.
"It is the signal." A weak signal produces dropouts, delay and robotic artefacts. It does not make your voice silent to the other party while the call stays connected. Silence is a microphone or routing symptom.
"I will just restart and it will be fixed." A restart does clear stuck audio routing often enough to be worth trying, but if Bluetooth is reconnecting automatically, the problem returns within minutes. Restart treats the symptom; forgetting the device treats the cause.
"Cleaning the openings with a pin or compressed air." A pin scratches the mesh and can push debris further in. Compressed air blown hard at close range can drive lint deeper. Soft brush, low angle, no liquid.
"The other person's phone is at fault." Occasionally true. If one contact consistently sounds bad and everyone else is fine, it is worth asking them to check their end before you spend anything.

A short order to work through

Confirm which side is failing — you, them, or the route.
If it is them hearing you: speakerphone test, case off, openings clean.
If it is you hearing them: set call volume during a call, then check the earpiece opening.
If it is routing: switch the audio route during the call, or forget the Bluetooth device.
Only after all of that, treat it as hardware.

The pattern across all of it: the phone is usually doing something deliberate, and the fix is to correct the condition rather than to overpower it. If the problem is specifically about things connecting and disconnecting rather than audio quality, see Bluetooth, Wi-Fi and CarPlay problems and iOS 27 Bluetooth issues. If it is CarPlay that keeps grabbing the audio, that has its own explanation. And if calls are not arriving at all rather than sounding wrong, that is a different fault covered in notifications not arriving or delayed.