We're investigating a problem with VoIP registrations and calls failing.
The problem is between our call servers and the RADIUS servers which handle authentication and call routing logic. This is still being investigated at the moment.
After adding additional RADIUS servers phone registrations and calls are working again. We're still investigating the problems with the original RADIUS servers.
The original RADIUS servers are still not working, we'll carry on the investigation in to this in the morning.
All RADIUS servers are back up and running normally.