The main telephone companies in New Zealand are Telecom, TelstraClear and Vodafone (which only deals with mobile phones). Pricing plans vary widely.
Most houses will have a telephone already installed. If not, one can be purchased from an electronic goods retailer or telephone company. Your telephone should be connected within two or three days of contacting a telephone company.
Telephone books are supplied free. Each major city has its own telephone book, and other areas are covered by provincial telephone books. The White Pages version lists residential numbers and the Yellow Pages version lists business numbers.