Das erste Wartungsupdate..

iOS 12.3.1 includes bug fixes for voice over LTE calls as well as iMessage filtering and reporting:

* 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