A free version of the service has been live since last Christmas but Telecom is now commercialising the scheme.
About 175,000 people had registered to use the hotspots during the trial period, the company said.
Chris Quin, Telecom's retail chief executive, said users would need to register once for access to the network and a user's device would then automatically connect to a hotspot when within range.
"We want to encourage our customers to use as much data as possible, because we know how the smartphone applications and services they're using are at the very centre of the way people now live, work and play," Quin said.
The WiFi network would be spread throughout New Zealand but with a particular concentration in Auckland, Wellington, and Christchurch.
Key holiday spots would also get a higher concentration of the hotspots, Quin said.
Martin Snedden, head of the Tourism Industry Association New Zealand, said the WiFi network would benefit the local tourism sector.
"More wifi hotspots will translate into happier visitors and enhance New Zealand's international image as a connected nation," he said.
"We know that free wifi is very popular with travellers and improves their overall visitor experience."
The hotpots have a radius of about 100m in ideal conditions, but this depends on factors such as the local landscape and whether there is clear line of sight to the WiFi transmitter.
Non-Telecom customers who have already signed up to the service, or who do so by mid-October, will be able to continue to trial it for free until early December.
Others will get a one-week free trial if they sign up from mid-October.
Telecom said it was working on introducing a range of other pricing plans to allow for greater flexibility.
A complete list of WiFi zones can be found here.
