Can I use a mobile phone bought from another country in NZ?

I live in New Zealand. If I bought a mobile phone on ebay from another country like Hong Kong, could I use it on the Vodafone network and put a sim card in it?|||As a person from the states, I wouldn't be able to use a mobile from another country unless the service provider allowed it. However, you are from New Zealand, so it would almost definitely be different. The safest route would be to check with the service provider.|||Yes, you can. I brought my phone with me from the US, but I had to have it "unlocked" to use the frequencies in New Zealand. Not a difficult thing to do and cost about $50NZD. Then bought a SIM card and have been using it without any problems since. It also works when I go back to the states, just get a SIM card and one month or so of service.