Hello, We understand how frustrating it can be when you are unable to answer calls due to a freezing app.
Have you tried clearing the app cache? https://www.samsung.com/us/support/answer/ANS00077611/
We recommend restarting the phone after clearing the cache of the app.
If the phone app continues to freeze, we recommend clearing the cache partition of the phone and repairing apps in the recovery menu.
To get to recovery mode:
- Turn off phone
- Once off, hold down volume up and power buttons simultaneously
- When Samsung logo appears, release power button BUT KEEP HOLDING VOLUME UP until the recovery menu appears
- Use volume buttons to navigate down to clear cache (NOT CLEAR DATA/ FACTORY RESET)
- Use power button to select.
- Run the repair apps option and your device will restart.
If you are still experiencing concerns with the Phone app, the next step would be a backup and factory reset of the phone. https://www.samsung.com/us/support/answer/ANS00062029/
If the app continues to freeze after a reset, service is recommended. You can use the following link to find a list of service centers in the U.S. that can do the repair: http://www.samsung.com/us/support/service/ or by contacting customer support at 1-800-726-7864.
For assistance outside the U.S., please use this link: https://www.samsung.com/us/common/visitlocationsite.html