One NZ begins phased 3G shutdown, starting Dunedin

One NZ has begun the phased shutdown of its 3G mobile network, starting in Dunedin, as the company reallocates spectrum to support wider use of 4G and 5G services across New Zealand.

The move follows several years of network preparation and customer outreach and is intended to free up radio spectrum currently used by older technology. One NZ said the process would be rolled out region by region, with Dunedin the first area affected.

Network shift

"After years of preparation and customer communication, Dunedin will be the first city where we switch off 3G, starting tomorrow on Tuesday 20 January," said Kieran Byrne, Chief Technology Officer, One NZ.

One NZ said retiring 3G allows it to use the same spectrum more efficiently for newer mobile standards. The company expects this to improve speeds, coverage, and network reliability for most users who already rely on 4G or 5G devices.

"Switching off 3G lets us deploy more of our radio spectrum into 4G and 5G, meaning faster speeds, better coverage and a more reliable network for our customers," said Byrne.

Upgrade programme

The shutdown follows a year of network investment across the country. In 2025, One NZ completed 258 mobile network upgrades, extending 4G coverage to all of its mobile sites and expanding 5G availability at a large number of locations.

The company said these upgrades were designed to handle rising data demand, particularly during peak travel periods, and to ensure continuity of service as older technologies are retired. Every One NZ mobile site now supports 4G, with many also equipped for 5G.

Industry-wide, mobile operators have been progressively moving away from 3G technology as device usage shifts and networks become more data-intensive. Spectrum released from 3G services is commonly reused to strengthen newer standards that can carry more traffic more efficiently.

Customer readiness

While most customers are already using compatible devices, One NZ said some users may still rely on 3G for voice calls or data. These customers will need to upgrade their phones or change settings to continue using mobile services as the shutdown progresses.

"The good news is most customers are already on 4G and 5G, but if you or someone in your whānau is still using a phone that relies on 3G for calling, now's the time to upgrade. Dunedin switches off 3G from tomorrow with the rest of the country to follow by the end of March," said Byrne.

To help customers assess their devices, One NZ said users on any network can send a free text message with the number 3G to 550 to check whether their handset will work on its 4G and 5G networks.

Device options

One NZ said 4G-compatible phones are available through its retail channels, with entry-level models starting from NZD $39. The company said special prepay offers are available in stores, aimed at customers who need to replace older handsets before 3G access is removed.

Customers with compatible phones may also need to ensure software is up to date and that settings such as 4G calling or VoLTE are enabled. One NZ has previously said some voice calls may play a recorded message ahead of full 3G shutdown to remind users of the change.

Wider rollout

The Dunedin switch-off represents the first stage of a broader national programme that will extend to other regions over the coming weeks. One NZ has indicated that the remaining areas of the country will transition away from 3G in stages, with the process expected to be completed by the end of March.

As the shutdown progresses, the company said it does not expect a material reduction in overall coverage, although some localised changes in signal behaviour may occur due to differences between technologies.

For One NZ, the transition marks a further step in shifting its mobile network towards newer standards that are expected to support future demand. With all sites already enabled for 4G and a growing share upgraded to 5G, the company said the retirement of 3G is intended to simplify network operations while expanding capacity where it is most used.