Linetest

A linetest is a critical diagnostic process used by New Zealand internet service providers (ISPs) and network wholesalers like Chorus to determine the health and stability of a broadband connection. Unlike a standard speed test, which simply measures data throughput, a linetest delves into the physical layer of the connection, examining the integrity of the copper or fibre-optic cables running from the local exchange to your premises. For Kiwis experiencing intermittent dropouts, high latency, or sudden speed degradation, performing a linetest is the first professional step in identifying whether a fault lies within the home's internal wiring or the external national infrastructure. This article explores how these tests function across different technologies like UFB fibre and VDSL, and how you can initiate one to restore your digital reliability.

Understanding the mechanics of a professional linetest

When a service provider initiates a linetest, they are essentially sending a series of electrical or light pulses down the physical line to measure response times and signal loss. In the context of New Zealand's aging copper network, a VDSL or ADSL linetest checks for "crosstalk" (interference from other lines) and "attenuation" (the weakening of the signal over distance). For modern Ultra-Fast Broadband (UFB) fibre connections, the process is slightly different; the linetest verifies the status of the Optical Network Terminal (ONT) and ensures that the light signal remains within the acceptable decibel range. If the test reveals an "out of spec" result, it provides the technical evidence required for your provider to log a formal fault with Chorus or a local fibre company for a physical repair.

• Physical Integrity: The test checks for physical breaks, water damage in roadside cabinets, or degraded copper joints.
• Signal Loss: Measures how much signal is lost between the local exchange and your wall jack.
• Sync Speed: Determines the maximum possible speed the physical line can currently support, regardless of your plan.
• Authentication: Verifies that the modem is correctly handshaking with the provider's server.

Physical Integrity: The test checks for physical breaks, water damage in roadside cabinets, or degraded copper joints.

Signal Loss: Measures how much signal is lost between the local exchange and your wall jack.

Sync Speed: Determines the maximum possible speed the physical line can currently support, regardless of your plan.

Authentication: Verifies that the modem is correctly handshaking with the provider's server.

The role of the Chorus Line Test API

In the New Zealand telecommunications ecosystem, Chorus provides a "Line Test API" that allows retail service providers like Spark, One NZ, and 2degrees to run real-time diagnostics. This tool gives providers a snapshot of what is happening at the ONT or the roadside cabinet without needing to send a technician to the site. When you call your provider's helpdesk, the agent is often using this API in the background to see if your modem is "syncing" or if there is a known outage in your Auckland or Christchurch suburb. .Read more in Wikipedia.

How to initiate a linetest for your home connection

While most deep-level linetests must be triggered by your ISP, many New Zealand providers now offer "self-service" diagnostic tools within their mobile apps. These tools perform a basic linetest by checking the heartbeat of your connection and identifying any obvious regional outages. If you suspect a line fault, the most effective way to start the process is to log into your provider's app—such as the Spark app or One NZ's "Check Connection" tool. If the automated test fails or returns an "unstable" result, the app will typically prompt you to book a technician or provide a reference number to use when calling the support team.

• Provider Apps: Use the official ISP app to run an automated diagnostic test from your smartphone.
• Online Portals: Log in to your account on the provider's website to access "Manage My Connection" features.
• Phone Support: Call the technical support line and specifically ask the agent to "run a linetest" on your physical connection.
• Visual Inspection: Before calling, check your ONT for a red "LOS" (Loss of Signal) light, as this confirms a physical line break.

Provider Apps: Use the official ISP app to run an automated diagnostic test from your smartphone.

Online Portals: Log in to your account on the provider's website to access "Manage My Connection" features.

Phone Support: Call the technical support line and specifically ask the agent to "run a linetest" on your physical connection.

Visual Inspection: Before calling, check your ONT for a red "LOS" (Loss of Signal) light, as this confirms a physical line break.

Distinguishing between Wi-Fi issues and line faults

It is vital to confirm that your "internet issue" is actually a line fault before requesting a professional linetest. If your devices work perfectly when standing next to the router but drop out in the bedroom, the issue is Wi-Fi interference, not a line fault. To prove a line issue, you should always test your connection using a physical Ethernet cable plugged directly into the modem. If the internet remains unstable while "wired in," you have sufficient evidence to demand a linetest from your provider.

Common results and what they mean for your service

A linetest result typically comes back as either "Clear," "Failing," or "Intermittent." A clear result suggests that the physical network is healthy, and any issues you are experiencing are likely due to your internal router settings or Wi-Fi environment. A failing result is actually good news for troubleshooting, as it provides a "smoking gun"—clear evidence that Chorus needs to fix a physical cable. Intermittent results are the most frustrating, often caused by "noisy" lines where electrical interference or a loose connection only causes issues during certain times of the day or during heavy rain.

• Clear / No Fault Found: The line is physically fine; look into your router or Wi-Fi setup.
• Sync Loss: The modem is struggling to maintain a connection to the exchange.
• Low Light Levels (Fibre): The fibre-optic signal is too weak, often due to a dirty connector or a bend in the cable.
• Crosstalk (Copper): Your internet is being slowed down by interference from a neighbour's line.

Clear / No Fault Found: The line is physically fine; look into your router or Wi-Fi setup.

Sync Loss: The modem is struggling to maintain a connection to the exchange.

Low Light Levels (Fibre): The fibre-optic signal is too weak, often due to a dirty connector or a bend in the cable.

Crosstalk (Copper): Your internet is being slowed down by interference from a neighbour's line.

Avoiding the "No Fault Found" fee

In New Zealand, if you request a technician to visit and they find the fault is caused by your own equipment (like a cheap Ethernet cable or a poorly placed router), you may be charged a "No Fault Found" fee, which can exceed $150. Running a self-diagnostic linetest through your provider's app first is a critical step to avoid this cost, as the app will only suggest a technician if it detects an actual issue on the network side.

Troubleshooting before your linetest: The power cycle

Before you spend time on the phone requesting a linetest, you must perform a controlled power cycle of your hardware. This is the first question any NZ support agent will ask you. A power cycle clears the cache of your modem and ONT, allowing them to re-establish a "clean" handshake with the local exchange. For fibre users, the sequence is critical: turn off both the ONT and the modem at the wall, wait 60 seconds, turn on the ONT first and wait for the "Optical" light to turn solid green, and then finally turn on your modem.

• The 60-Second Rule: Unplug everything for at least one minute to ensure all electrical charge is dissipated.
• Sequential Start: Always power up the network-side hardware (ONT) before the consumer-side hardware (Modem).
• Check the Patch Cable: Ensure the thin fibre cable between the wall and the ONT is not kinked or pinched by furniture.
• Bypass Splitters: If you are on VDSL, remove any unnecessary phone line splitters and plug the modem directly into the main jack.

The 60-Second Rule: Unplug everything for at least one minute to ensure all electrical charge is dissipated.

Sequential Start: Always power up the network-side hardware (ONT) before the consumer-side hardware (Modem).

Check the Patch Cable: Ensure the thin fibre cable between the wall and the ONT is not kinked or pinched by furniture.

Bypass Splitters: If you are on VDSL, remove any unnecessary phone line splitters and plug the modem directly into the main jack.

The importance of the "Master Jack" for VDSL

For New Zealanders still on copper-based VDSL, the quality of your internal wiring is a major factor in linetest results. Older homes often have multiple phone jacks that create "bridge taps," which act as antennas for electrical noise. To get the best linetest result, your modem should be plugged into the "Master Jack"—the first point where the phone line enters the house. If your internet is slow at a secondary jack but fast at the master jack, your internal wiring is the culprit.

Why distance matters for VDSL and ADSL linetests

If your linetest for a VDSL connection shows a low "sync speed," it is often due to the physical distance between your house and the roadside cabinet. Unlike fibre, which maintains its speed over long distances, copper signals degrade rapidly. If you are more than 800 metres from the cabinet, your VDSL stability will drop significantly. A linetest will confirm your "loop length" (the total distance of the copper wire). If the distance is too great, no amount of technical tweaking can increase your speed, and your best option is to look into 4G/5G wireless broadband or wait for a fibre upgrade in your street.

• Loop Length: The total distance of copper cable from the exchange/cabinet to your house.
• Line Attenuation: The loss of signal strength as it travels through the copper.
• SNR Margin: The "Signal-to-Noise Ratio"; if this is too low, your internet will drop out constantly.
• Cabinet Upgrades: Check the Chorus map to see if a closer cabinet is planned for your area.

Loop Length: The total distance of copper cable from the exchange/cabinet to your house.

Line Attenuation: The loss of signal strength as it travels through the copper.

SNR Margin: The "Signal-to-Noise Ratio"; if this is too low, your internet will drop out constantly.

Cabinet Upgrades: Check the Chorus map to see if a closer cabinet is planned for your area.

The "Copper Withdrawal" program in NZ

Chorus is currently in the process of "withdrawing" copper services in many Auckland and Wellington suburbs where fibre is available. If your copper linetest is consistently failing, your provider may refuse to fix the line and instead offer you a free upgrade to fibre. This is part of a national push to move New Zealanders onto more reliable and energy-efficient technology.

Linetesting for 4G and 5G wireless broadband

Wireless broadband does not have a physical "line" to test in the traditional sense, but providers can still perform a remote diagnostic on your wireless modem. Instead of checking for cable integrity, a wireless linetest looks at "RSRP" (Signal Power) and "SINR" (Signal Quality). If you are experiencing slow speeds on a wireless modem, the test will reveal if your device is connected to a congested cell tower or if it is suffering from poor indoor reception. Often, a "failing" wireless test can be solved simply by moving the modem to a higher shelf or closer to a window facing the nearest cell tower.

• Signal Strength (RSRP): Measures how much raw cellular signal the modem is receiving.
• Signal Quality (SINR): Measures how "clean" the signal is; high noise leads to slow speeds.
• Cell Loading: Determines if too many people are using the same tower at once (common during evening peaks).
• Tower Distance: Identifies which specific cell tower your modem is authenticated with.

Signal Strength (RSRP): Measures how much raw cellular signal the modem is receiving.

Signal Quality (SINR): Measures how "clean" the signal is; high noise leads to slow speeds.

Cell Loading: Determines if too many people are using the same tower at once (common during evening peaks).

Tower Distance: Identifies which specific cell tower your modem is authenticated with.

Using external antennas to boost wireless results

If your remote diagnostic shows a weak signal, you might consider an "external antenna" setup. This involves mounting an antenna on your roof that connects to your wireless modem via a cable. This bypasses the insulation and walls of your home, often transforming a failing wireless linetest into a high-speed, stable connection.

The impact of home renovations on line quality

A common but overlooked cause of failing linetests is accidental damage during home renovations. In New Zealand, many older fibre and copper lines are buried just a few centimetres below the surface in gardens or run through wall cavities. If a contractor accidentally "nicks" a cable with a spade or a drill, the connection might still work but will become highly unstable. A professional linetest can identify these "partial breaks" by showing an unusual spike in signal reflection (known as TDR testing). If you've recently had work done on your property and your internet has since become unstable, mentions this to your ISP when requesting a test.

• Garden Dig-ups: Fibre cables are thin and easily severed by shovels or lawn edgers.
• Wall Cavity Damage: Drilling into walls can occasionally snag or strip the insulation of internal wiring.
• Moisture Ingress: If a cable jacket is damaged, rainwater can seep in and cause intermittent shorts.
• Rodent Damage: In some New Zealand suburbs, rats chewing on cables in roof spaces is a frequent cause of line failure.

Garden Dig-ups: Fibre cables are thin and easily severed by shovels or lawn edgers.

Wall Cavity Damage: Drilling into walls can occasionally snag or strip the insulation of internal wiring.

Moisture Ingress: If a cable jacket is damaged, rainwater can seep in and cause intermittent shorts.

Rodent Damage: In some New Zealand suburbs, rats chewing on cables in roof spaces is a frequent cause of line failure.

Protecting your line during DIY projects

If you are planning any landscaping, always "dial before you dig." While this is usually for major utilities, Chorus provides a free service to show where fibre lines are located on your property. Keeping your fibre line safe is far easier than trying to resplice a damaged glass strand after the fact.

Preparing for a technician visit after a failed test

If your linetest fails and your provider books a Chorus technician, you should prepare your premises to ensure the visit is productive. Clear the area around your ONT and the internal "lead-in" point where the cable enters the house. If you are on a copper connection, ensure the technician has access to all the phone jacks in the house. It is also helpful to have a list of specific times when the internet drops out, as this can help the technician identify if the fault is related to local electrical interference (like a street light turning on) or a weather-dependent physical fault.

• Clear Access: Move furniture away from the ONT and the main phone jack.
• Pet Management: Ensure dogs are secured, as technicians may need to move between the house and the roadside cabinet.
• Stay on Site: An adult must be present for the duration of the visit, which can take between one and four hours.
• Test History: Show the technician your recent speed test results or the "failed" status in your ISP app.

Clear Access: Move furniture away from the ONT and the main phone jack.

Pet Management: Ensure dogs are secured, as technicians may need to move between the house and the roadside cabinet.

Stay on Site: An adult must be present for the duration of the visit, which can take between one and four hours.

Test History: Show the technician your recent speed test results or the "failed" status in your ISP app.

Understanding the "Chorus Boundary"

It is important to know that the Chorus technician is generally only responsible for the line up to the "Network Termination Point" (usually your ONT or the first phone jack). If the fault is in your own internal wiring or your personal router, they may offer to fix it for a fee, or they may simply declare the "network" healthy and leave the rest to you.

Final thoughts

A linetest is the most powerful tool in your arsenal when fighting against an unstable internet connection in New Zealand. By providing a deep technical look at the physical health of your fibre or copper line, it removes the guesswork and points directly to the cause of your lag or dropouts. Whether you initiate a test yourself through a provider app or work with a support agent to trigger a professional Chorus diagnostic, staying informed about the process ensures you can advocate for a fast and effective repair. In our high-speed digital world, ensuring your physical "pipe" is in top condition is the only way to truly enjoy the benefits of New Zealand's world-class broadband infrastructure.

Frequently asked questions

What is a linetest?

A linetest is a technical diagnostic performed by your internet provider to check the physical health and signal quality of the cables connecting your home to the national internet network.

How do I run a linetest on my own?

You can usually run a basic linetest using your internet provider’s mobile app (like the Spark or One NZ app). For a more detailed test, you must contact your provider’s technical support team.

Does a linetest fix my internet?

No, a linetest identifies the problem. Once the fault is identified—such as a physical break or electrical interference—your provider can then send a technician to fix it.

Why is my linetest showing "No Fault Found" when my internet is slow?

This usually means the physical line is healthy, but the problem lies with your internal Wi-Fi, your router settings, or a specific device you are using.

Is there a fee for a linetest?

Running a remote linetest is free. however, if a technician visits your home and finds that the fault was caused by your own equipment, you may be charged a "No Fault Found" fee.

What does a red light on my fibre box mean?

A red LOS (Loss of Signal) light means that the fibre-optic signal is not reaching your house, which will cause a linetest to fail immediately. This usually requires a physical repair.

Can rain affect my linetest results?

For old copper lines (VDSL/ADSL), rain can cause moisture to seep into damaged cables and cause a linetest to fail. Fibre-optic cables are generally unaffected by weather.

What is "Sync Speed" in a linetest?

Sync speed is the maximum speed that your physical line can handle. If your sync speed is lower than your plan's speed, you will never be able to reach your full internet potential.

How long does a linetest take?

A remote automated linetest typically takes between 30 seconds and 5 minutes to complete. A professional on-site linetest by a technician can take up to an hour.

Can a VPN affect my linetest?

A linetest checks the physical cable, so a VPN will not affect the results. However, you should always disable your VPN before running a standard speed test to ensure accuracy.