(Sorry about the text, I cant paste links) Back in 2014 the Chaos Computer Club demonstrated if you know any cell-phone number in the world, you can use the SS7 (Signal System 7) protocol to ask the network for that numbers nearest cell tower, getting it's location to about 200metres. 

A SS7Map website found using SS7 NZ claims 1 out 1 NZ networks tested is partially vulnerable, but doesn't list which on.    

Is NZ still vulnerable to domestic or overseas amateur triangulation?   

It's not my area of expertise and someone who works with domestic violence has flat out asked me if cell phones can be traced by anyone who isn't in the phone company?