MT65xx. Why doesn't it let me answer my calls?

Solved: Cannot answer incoming calls - Samsung Community - 2447918

Reboot and Clear Cache Partition:

Reboot your phone to the Maintenance (Recovery) screen.
Select "Clear Cache Partition."
Next, choose the "Repair Apps" option.
Allow the phone to reboot automatically and give it 2-3 minutes to finish.
After that, try answering calls again.

Try a Different Phone App:

Install a different phone app (such as Google Phone) and compare its behavior.
You can switch back and forth between the two apps to see if either allows you to answer calls.

Check for Driver Issues (if applicable):
If you're using a MediaTek device (MT65xx), there's a specific workaround:

Take out the battery, SD card, and SIM card from your phone.
While holding the volume up button, connect your phone to your PC via USB.
Once you hear a sound from your PC, release the volume up button.
Open Device Manager on your computer (you can search for it or find it in the Control Panel).
Wait for 2-3 minutes; you'll hear a sound, and another device will be displayed.

If none of these steps resolve the issue, consider contacting your carrier for further assistance