To enable this feature on your iPhone, go to Settings-> General-> Accessibility-> Phone Noise Cancellation, then make sure it is enabled or turned on. ... Restart your phone after making necessary changes to these settings then see if that fixes the problem.
How to fix static noise, audio cutting off, and no sound problems ... - iKream
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If your Android phone keeps cutting out during calls, install the latest Android updates and restart your device. You can also remove your SIM card and turn off Voice Privacy during calls. If the issue persists, use Wi-Fi Calling, and contact your carrier for further help.
Fix: Android Phone Keeps Cutting Oout During Calls - Technipages
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If your iPhone keeps shutting off and your it won't charge or keeps crashing, it might be time for a hard reset. Whether it's really shutting down on its own, or it's rapidly depleting the battery due to rogue processes or Wi-Fi or cellular radio activity, a hard reset can help.
iPhone or iPad keeps shutting off? Here's how to fix it! | iMore
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