RoamTheWorldCellPhones.com

Cellphone GSM Frequencies: 900/1800

(This means you will need a GSM cellphone that will work on 900MHz or 1800Mhz to use it in New Zealand.)

Cellular carriers for New Zealand

Two Degrees Mobile Limited (2degrees)

Frequency: GSM 900/1800
Website: www.2degreesmobile.co.nz

Coverage Map (NONE)

Vodafone Mobile NZ Limited

Frequency: GSM 1800
Website: www.vodafone.co.nz

Coverage Map (900Mhz)
Coverage Map (1800Mhz)

If you've used either of these networks or roamed in New Zealand, please post about your experience and the cost. Feel free to ask questions.