New Zealand's electricity supply runs at 230/240 volts, and we use angled two or three pin plugs (the same as Australia).
All public phones take call cards purchased from bookstores and newsagents. These require you to call a free 0800 number, enter the pin code from the card, and then make your call. Some public phones also accept credit cards, but very few accept coins.
Check with your phone company before leaving home about international mobile roam facilities available in New Zealand. Alternatively you can hire/buy mobile phones or SIM cards in New Zealand. Note that signal is not available in all rural areas.
Find out more about internet and WiFi access in New Zealand.