@Dolice: Does the issue occur while viewing maps online, offline, or both? I'm not sure what could be causing this, but to troubleshoot the issue please tap the Recent Apps button on your Navigation Bar, and close down any background apps that are running in the background by swiping upwards on the preview window. Now, press the Volume Down and Power buttons together for around 10 seconds until the phone restarts, as this will perform a Soft Reset and address any temporary issues that might be affecting the overall performance. If the issue persists, head to Settings > Apps > Google Maps > Storage > Clear Cache. It is also worth checking the app settings: Google Maps > Tap the 3 lines in the top left > Settings > Start Maps in Satellite View > Off > Show Scale On Maps > Always (instead of when zooming in and out).
@cazmac8: Can you try opening the Phone app > Tap the 3 dots in the top right > Settings > Voicemail > Service Provider > Make sure your carrier is selected > Voicemail Settings > Voicemail number > Ensure that a number is populated here. If not, contact your network directly to obtain the relevant number, and enter it here.
You can also go back to the Call Settings > Supplementary Services > Call Forwarding > Voice Call, and add your voicemail number to the Forward When Busy, Forward When Unanswered, and Forward When Unreachable sections, depending on your preference. I hope this helps.
