What do I add to the front of a new zealand phone number so I can text it from australia with my australian number?

64 for normal numbers, the rest depends what town you want?
You could Google NZ White Pages for phone codes.
good luck
How do we know these things? Well I’m Scottish, my wife be a Kiwi, and my poor long suffering children, why they be Australian…
C’mon man we invented the phone along with everything else, well ok nearly everything else!

Lose the leading 0 and replace with +64.

either 0064 or +64 and don’t include the first 0 of the phone number

e.g.
021*****
would be 006421*****