Everyone connected to the fibre network has this white plastic box terminal. Bill Bennett unravels its mysteries and talks about the capabilities of the next generation ‘box’

Every home and business connected to the fibre network has an Optical Network Terminal or ONT. It’s a white plastic box that is usually mounted on an inside wall at the point fibre enters the building.

Chorus change manager Jacques de Villiers says the ONT converts light carried by the Chorus fibre network into electrical signals that your television, computer and other devices can use. He says it is an essential piece of equipment for fibre customers.

He says there is a lot inside the ONT. Some newer models have WiFi and Ethernet ports for home networking as well as the expected phone port. The ONT uses electricity provided by its customer – the device plugs into the mains grid.

At the time of writing, Chorus is on its third generation residential ONT. De Villiers says it was introduced a year ago, in early 2019.

“We moved to the third generation ONT mainly because only two organisations in the world were using the second generation device: Chorus and NBN in Australia. That meant that parts and long-term support could become a risk,” he says.

“The third generation ONT is in more widespread use around the world. This means there is less risk. It’s also newer, which means it can do more, specifically it can provide layer three capability (see Layer 3 explained on the next page). We are looking into using these features at the moment.”

What this means in practice is that an ONT can also be a router. You won’t need a second device. That’s one less connection, one less power socket needed in your home.

De Villiers says with first and second generation ONTs customers need a router to route the signal to the network.

The third generation ONT has four gigabit Ethernet ports built in, along with a Wi-Fi access point. Like most modern wireless routers, the ONT Wi-Fi operates on both 2.4GHz and 5GHz.

De Villiers says a trial of the ONT as a router is underway. Chorus was talking to retail service providers (RSPs) about how this can work as The Download went to press.

Among other issues, the trial will look at how to provide support and troubleshoot problems. It’s a question of determining where Chorus and RSPs draw the lines of responsibility. De Villiers says that in some cases, it will be as simple as telling someone to switch the ONT off and on again.

One area of concern is that some customers get to tweak the settings on their Wi-Fi routers for better or specialist performance. De Villiers says that’s something Chorus will need to work with RSPs on. He says: “As soon as we lock down the ability to tinker, we’re closing off that part of the market. But, if we open it up, we increase the risk that someone will configure it incorrectly and even break things.”

A possible approach to this is to let RSPs log in remotely and do their own configurations.

Another problem is that some early fibre adopters installed their ONTs inside a comms cabinet. These are typically made of metal, which means Wi-Fi is not going to work. This will be another issue for RSPs to work through with Chorus.

In some cases customers have uninterruptible power supplies, so a fibre connection can continue to work in a temporary electricity outage. Chorus has back-up power at exchanges that can keep connections running until, say, a generator kicks in or power is restored.

Chorus’ plan is to work with RSPs who will be able to make the newer ONT available to customers now using the older hardware.

De Villiers says this is optional for the RSPs. “They can choose to take them. We don’t have pricing or a commercial contract around it yet. They can choose whether to use them or whether they will continue to supply routers. It will probably have a price associated with it and RSPs will most likely pass it on to customers,” he says.


Replacing the ONT means touching the fibre. De Villiers says the glass is fragile, so it has to be done by a skilled technician. Chorus is nervous about other hands touching its fibre; it introduces a lot of risk.

That said, Chorus designed its ONT to be future-proofed. De Villiers says there is an easy upgrade path for people wanting the new device.

Because an ONT is always on, it has to be reliable. De Villiers says while consumer electronic devices are often built to offer a mean time to failure of five years, the Chorus ONTs are specified for a 50-year time-frame.

He says: “At the moment, our standard is the third-generation ONT. If you are getting a new connection, you’ll get one of these. We are releasing information about the ONT at a site for the RSPs, so they will be able to make an educated call about whether they choose to order a replacement for the customer or stay with what they have.”

Businesses and customers on the new Hyperfibre service get a different ONT. The Hyperfibre version is enabled for layer three so it works as a router. It includes a 10Gbps Ethernet port along with three gigabit ports and Wi-Fi capability.

At the time of writing, business customers are either on their second-generation ONT or a small form-factor pluggable (SFP) device.

Another generation of ONT is on its way. De Villiers says there is no need at the moment for a new generation of residential ONT. “That has a lot of life still in it. However, I think we are going to introduce different ONTs for different capabilities. There is a demand for this with corporate users, and there will be a need for versions to go into things like ATMs or traffic lights.”

De Villiers says ONT innovation is starting to ramp up, with new products and capabilities coming thick and fast. “New Zealand was ahead of the market. Now most of the rest of the world is moving to fibre services. As more countries roll out fibre networks, there is going to be demand for new hardware capabilities and a lot more fresh ideas.” 


The telecommunications industry uses layers to refer to different parts of network communications.

Layer 2 is the data link. It’s where data packets are encoded and decoded by electronics at each end of the connection. The service Chorus delivers to your building is Layer 2. At present, the ONT is the device that decodes the signal at your end. From here, it hands over to your router, usually a Wi-Fi router.

Layer 3 handles switching and routing. It creates paths between end points and handles problems like errors, congestion and so on. In effect, your home router gives you Layer 3.





Jacques de Villiers is a Change Manager at Chorus and has been in the telco industry for 11 years.