Thank you for sharing your concern. We acknowledge your query and apologize for the same. And please follow the easy troubleshooting steps which might help to solve the issue.
We would like to inform you that, if you are using Airtel SIM services then volte options are being removed by Airtel itself. So, your smartphone will automatically work on the default settings of volte. If, you are using any other SIM Card then try to contact your particular network service provider. So, to get your issue resolved, kindly contact your network service provider.
In case the issue still occurs. Please register your concern in Samsung Members Application (Open Samsung Members Application > Get help > Send Feedback > Ask question).
Thank you for writing to Samsung. Warm regard, Samsung customer support
