We know that mobile networks are under stress and voice calls are failing. This is the response from Spark:
Following the Prime Minister’s COVID-19 announcement today telecommunications providers experienced call volumes beyond any level of calling ever seen in New Zealand to date.
This is creating significant congestion for voice calling at an industry-wide level.
We are working collaboratively to rectify the issue with urgency.
While broadband has seen increases, these have been within manageable volumes. So in the meantime New Zealanders are encouraged to use internet-based calling options such as Skype or Facetime or text applications like WhatsApp.