Apple has released its one of most powerful iPhone till date which is iPhone X. The phone is equipped with many advanced features in it but many users are having different complaints about the iPhone. These can be related to iOS bugs but users don’t wish to see many issues on such an expensive piece.
Some iPhone X users are not able to make call over VOIP apps like facebook or whatsapp. Everytime user attempt to make a call, Voice and Video calls over Facebook Messenger and WhatsApp have been failing. But when tried with old iPhone 7 Plus and make the same call and it works. Users have updated apps to latest version and also reinstalled the apps but the issue still persists.
The Facebook and whatsapp support claims it be iPhone X related issue as the apps works fine on other devices. But there are no official statements from Apple side on this. However you may try below fix to check if it helps you.
Turn off hearing aid setting:
Please try to turn off hearing aid compatibility as this seems to interrupt VOIP calling.
Go to General->accessibility->turn off hearing aid compatibility. This should get the issue fixed.
Reset All Setting:
Go Settings->General->Reset All settings. Please take backup before doing this as this woule delete all the data stored in your iPhone X. Once done reset all settings. The issue should be gone.