I, like many people, have never had the luxury of being at a place which I have control/monitoring rights to where an International Pipe and National Pipe verge to be able to distinguish between International and National Traffic. The object of this was to supply >98% accuracy of determining a NewZealand IP from an International IP. Hopefully this attempt from my last one months ago will gather better results.
You are able to do a check on an IP to see if it is National or International, grab the full listing of current NewZealand subnet ranges in XML and/or HTML and future ability of accessing a SOAP API to use with your applications.
Enjoy :)
One page links to NewZealandSubnets:
http://nzip.meta.net.nz