Help Cell phone change countrys over?

Hey everyone i have my phone from aussie im Living in nz an i wanna use it so i can in nz i put my new zealand sim in an it comes up with sim unavailable please contact your derive provider i not keen to go in cause it is a hour an something drive from the farm i live on is there ways i can by pass it if yes please give me ya email or explain over this thank you! ps i am vodafone nz 2 might change to 2dergre