Spark are having issues with IP Centrex and Voice Connect in the South Island. I have just had this confirmed over the phone with them. But for whatever reason they haven't got anything on their Service Status page about it.

So if you are on IP Centrex or Voice Connect in the South Island and having issues with calls failing to connect, it may well be this.

I do have to wonder about the point of having a service status page if they don't keep it updated. Wasted my time investigating whether it was an issue with our phone server as the Spark status page listed no problems with their network, yet when I phoned them they were well aware of an issue.