same here.

And this is true for many (if not all) VoIP apps with callkit implementation.

Nevermind, they fixed it with an update

If the problem is still there, try booting into the Safe Mode using your normal account.  Disconnect all peripherals except those needed for the test. Shut down the computer and then power it back up after waiting 10 seconds. Immediately after hearing the startup chime, hold down the shift key and continue to hold it until the gray Apple icon and a progress bar appear. The boot up is significantly slower than normal. This will reset some caches, forces a directory check, and disables all startup and login items, among other things. When you reboot normally, the initial reboot may be slower than normal. If the system operates normally, there may be 3rd party applications which are causing a problem. Try deleting/disabling the third party applications after a restart by using the application un-installer or by using the developer’s uninstall instructions. For each disable/delete, you will need to restart if you don't do them all at once.

Safe Mode - About

Safe Mode - Yosemite

If it works in the Safe Mode, try running this program when booted normally and then copy and paste the output in a reply. The program was created by Etresoft, a frequent contributor.  Please use copy and paste as screen shots can be hard to read. On the screen with Options, please open Options and check the bottom 2 boxes before running. Click “Share Report” button in the toolbar, select “Copy to Clipboard” and then paste into a reply. This will show what is running on your computer. No personal information is shown.
  

Etrecheck – System Information

Press the Power and Home buttons until the Apple logo appears.

If your iPhone, iPad, or iPod touch won't turn on or is frozen - Apple Support

Hi i did the restore and it worked fine for couple of days and then same proboem.  Guys can you get apple sort that problem. 

Me too having same problem... Apple should take it seriously and solve this problem as soon as possible..

The easiest way is to delete the email account, then add it back. Depending on the type of account you may be able to change the password and other settings in Settings/Accounts & Passwords. But unless it is a POP account deleting and adding it is easier. (If it's POP you will lose any emails stored on the phone if you delete the account.)

Try checking the Do Not Disturb Setting. http://help.apple.com/iphone/11/#/iph3dd60e1f

I bought a used iPhone 5s and initially it had 10.1.1 on it. I had the exact same problem with the Bluetooth. I upgraded it to iOS 11.2.1 and I still had the same issues.

Then I bought a brand new iPhone X that had 11.2.1 already installed on it. The Bluetooth worked 100% fine.

I was reading about this Bluetooth issue with iPhone 5's right from when they were released in 2012. I think it was solved but iOS 10 seemed to bring this 2012 problem back. This has to be a hardware/software issue with the Bluetooth in the 5, 5c and 5s. It will not work properly with some hands-free devices.

Turn off Do Not Disturb.