Apple has released a follow-up iOS 12.3.1 update that crushes some bugs that related to VoLTE calls and iMessage. The update is now available to download and includes the following fixes:
Patch note is listed below:
- Fixes an issue that could prevent making or receiving VoLTE calls
- Fixes issues in Messages that could cause messages from unknown senders to appear in your conversation list even though Filter Unknown Senders is enabled
- Fixes an issue that could prevent the Report Junk link from appearing in Messages threads from unknown senders.
You can now download this by tapping the update button on your iPhone and iPad.