Cell Phone Service options in New Zealand
There are a couple to choose from, but to preface this section, I would check with your provider in your home country. We had our American T-Mobile phones in Australia and it would roam to any tower and was actually more reliable than our Oz phone. Without our T-mobile phones, we would have been stranded in Tasmania the entire time as our Vodaphone Oz phone didn't work anywhere, but Hobart. For our T-mobile plans we pay $10 a month for unlimited data (at 2g speeds) and unlimited text pretty much anywhere abroad. That means we could FaceTime, Face Time voice, and Facebook Messenger call, Instagram, Facebook, etc. as much as we wanted.
Although it is convenient to buy SIM cards at the Airport, they only had two brands, Vodaphone and Spark, available and I am pretty sure they do not offer the full packages they do in their stores. But if you go to any information center, you can usually pick up a 2 degrees SIM card for free. They roam seamlessly between their towers and Vodaphone towers.
For our first round of phone plans when entering NZ, we took on the convenience of buying the Spark Traveller's plan at the airport. Who knows why, I think it was because we wanted to have a contact number for all the vans we were sussing out. But they got us and once again we found out that our American phone service was more reliable purely because it connected to any tower it could (usually Vodaphone).
Coming from America, we are quite spoiled with our Data plans and have noticed that data plans abroad can be a joke by comparison. With hardly as many cafes offering free wi-fi, I can eat thru the max 3gb data in a couple days. Here in NZ to top up on data, it is $50 for another 3gb. Steep as.
Phone Companies in NZ:
Vodaphone seems to have some of the best coverage. When asking our family of four what service they used in their travels, they said they to also counted on their Canadian plans still rolling from their most recent van visit to Alaska, Canada and the USA. They said 90% of the time they always had Vodaphone service on their Canadian phones.
2 degrees seemed to have the cheapest bundle with the most data and unlimited calls to numerous countries abroad. The prices on bundles were more along the lines of the Australian prepaid, which was reasonable. They also have a data hunting app. Where you can pick up mb or gb's of data just around the area (If you are thinking this sounds like Pokémon Go, it kinda is) This data also rolls over to the next month if it goes unused. This is the service we chose in the long run.
Spark doesn't even care if you are 5 years old asking for a SIM card for your mom's iPad. If your have a visa or other credit card, they will give it to you without taking down any personal information. Very different experience from Australia. They need to see a license, passport, or if you do it over the phone, they run your name thru some government website to approve your visa status. The max amount of data they offered was 3gb, but they had wifi hot-spots available to cell phone customers whenever they were in range. The wi-fi hot spot was reminiscent of Australia's Telstra service (and they had the best most convenient hot spots in Oz). Anyways, I think that is why we hopped on Spark in the beginning. Apparently, connecting to the wi-fi didn't require an app. When your phone was in range it was just supposed to connect and override using the data. We connected to the Wifi via settings on the phone and it sent our phone a code to punch in...then, we were able to connect and it remained connected every time we were in range! I noticed the code worked for my laptop connection as well, which was quite handy. When we ran out of our 3gb data within the first week, we kinda dumped topping up our Spark and used our trusty T-mobile to navigate, but we still hit up those wi-if spots.
The Warehouse Phone Plans
Although we have not looked into this, apparently, this is one of the best deals around. They have "pick & go" options where you pay $4 per 4 hours talk, $4 for unlimited text, and $4 per GB. To top up on your data, just pay another $4 per GB or talk. It sounds simple and some friends we met on a hike have one Spark phone and one Wharehouse phone. They have the spark phone strictly for the hot spots and Wharehouse to have cheap data. Sounds like they are doing it right.