Unable to hang up / constant waiting beep sounds / need to restart to make a call

[zflip4user01]

I have an issue with zflip4 (One UI version: 5.1).

- Unable to hang up (a few times)
- One call has consistent waiting beep sounds after I picked up the call and persists for around 15 minutes until I hung up (it was an important call ... I could not hang up and call again).
- Occasionally need to restart the phone after I finish a call because I was not able to make a call after I hung up.
- (Off topic, but those pesky "One UI optimizing the app" messages appear during restart and it took at least 5 minutes after initiating a restart to be able to make the next call, which make this problem more painful).

Please let me know how to fix this problem.

Seems like the S series has a similar problem https://r1.community.samsung.com/t5/galaxy-s/phone-won-t-hang-up/m-p/22101152#M123709 but it has not been resolved. 

[Helenna]

Hi, we aprreciate your efforts in trying all the possible troubleshooting steps.

If you haven't tried to perform factory reset, please perform backup and factory reset the device by following the steps in the given links.

https://www.samsung.com/ca/support/mobile-devices/galaxy-phone-back-up-and-restore-data/

https://www.samsung.com/ca/support/mobile-devices/galaxy-phone-perform-a-factory-reset/

Also, please generate an error report by following the below steps:

Tap and hold on samsung Members Icon and tap on Error report >> select the category from the below >> Describe the issue and check the option "send system log data" then send.

An expert from the Samsung Members team will try and respond to the report as quickly as possible.