For customers experiencing any issues with their NBN service, we recommend the best thing to do first is check if there's an outage on the NBN network.
We have created this article that can guide you on How to Check for NBN Network Outage
If there are no known outages in your area, we recommend having a read of these community articles, which may help resolve your issue:
In your case, we have made some update on the system and your VoIP service should be working.
Let us know should you need further assistance.