(If you are behind a switchboard you may have to dial '0' or '9' (or another number) to get an external line.)
How the number is composed
00 is the international prefix used to dial somewhere outside of New Zealand.
1 is the international code used to dial to USA.
There are multiple city/area codes in use for Mobile. If does not work, you may try the others. The area codes used are: 334/251. (Not added because the number entered already seems to include an area code.)