When you're not using your iPhone as a music player, camera or gaming platform, you might actually use it as a phone. And when you do, call quality matters. If calls sound muffled or metallic, cut out intermittently or are drowned by background noise, you can take steps to fix the problems.

Most of the time, the causes are poor signal strength, outdated carrier settings or physical barriers like walls or metallic veneers on glass.

What you can try during the call

First, check your volume and speaker output. The volume might simply be turned down, or you might not have turned speaker mode on. Next, glance at the signal bars. If those are low, move toward a window or more open space.

You might not have noticed that you have the option to adjust the voice mode during a call. Voice Isolation is available on the iPhone XR/XS and newer, as long as you have iOS 16.4 or later. It uses machine learning to block environmental noise, so your voice sounds more audible to the other person.

To activate it during a call, swipe down from the top-right to open Control Center and tap the small Phone Controls banner at the top of the screen. Then under Audio & Video, select Voice Isolation from the available options in the Mic Mode section. You can also choose Automatic, which has your phone adjust for what's best. 

Of course, since these options apply to your voice, their enhancements only apply for the person you're speaking to. If you're having trouble hearing the person on the other end of the call and they also have an iPhone, ask them to try this option (as well as the others discussed here, if their calls always sound poor). 

Get a better cellular connection

If the nearest cellular tower is congested, your iPhone may connect to a more distant tower with a weaker signal. It could also cling onto a weak connection even when a stronger one is available. If your call drops or the sound is bad, end the call, then swipe down from the top-right to open Control Center. There, toggle Airplane Mode on, wait 10 seconds and toggle it off again. This forces your device to reconnect to the cellular network, hopefully with a stronger signal.

Switch to Wi-Fi Calling

With Wi-Fi Calling, your call is handled by a Wi-Fi connection instead of a potentially weak cellular network. It's a great option if cell reception in parts of your home is poor. To enable it, open Settings > Apps > Phone, tap Wi-Fi Calling, then enable Wi-Fi Calling on This iPhone. Wi-Fi calling should hand off to your cellular network if you leave Wi-Fi range mid-call, but this isn't perfect, so you might experience drops.

Update your software

Apple regularly patches issues that may impact call quality. Check Settings > General > Software Update to make sure iOS is current. You should also check your for carrier settings updates in Settings > General > About. If an update's available, a prompt should appear within 15-seconds. Tap Update.

Restart your phone

The oldest trick in the book still works to fix a lot of issues, so try restarting your iPhone if you haven't in a while. If your iPhone uses a SIM card, pop the tray out with a paper clip to check for dust or a loose fit (while the phone is turned off). 

Physical checks

Test your microphone by recording yourself using the Voice Memos app. If that playback sounds clear, you know it's not a hardware problem. 

Clean the speaker grill and earpiece with a soft brush, and try a call without a case since thick or metal cases can interfere with antenna performance. Also, try using speakerphone during a call to see if that makes a difference.

Headsets and AirPods

Bluetooth headphones, including AirPods, share the 2.4GHz band with a multitude of other devices including mice, keyboards, microwaves and baby monitors. This network congestion can degrade call quality. Try making calls without your headphones and see if the audio is any clearer. Or if you've never made a call with headphones, try them to see if they perform better than the internal mic.

Hardware faults

Some iPhone 12 and 12 Pro models had high earpiece failure rates, which Apple addressed in a now-closed service program. Older iPhones with Intel modems (iPhone XR, XS or 11) may also have weaker signal strength. You can contact Apple if you think a hardware issue is causing your problem, but this will likely result in having to come into the store for a paid session.