Full fibre installation: what happens, the equipment and your landline

Key takeaways

A new cable has to come into your home. Full fibre does not use the existing phone line, so there is some physical work: a small box outside, one hole through the wall, and a box inside.
You choose where the equipment goes, within practical limits. Pick a central spot near a double power socket. This decision affects your Wi-Fi for years.
Someone aged 18 or over must be present for the whole appointment and able to make decisions about drilling and cable routes.
Renters need the landlord's consent for drilling. In blocks of flats, the network also needs the building owner's agreement to install in shared areas.
The landline becomes digital. It plugs into the router and stops working in a power cut unless you have battery back-up. BT plans to retire its old phone network by 31 January 2027.
Tell your provider in advance if you have a telecare alarm, a monitored burglar alarm, or rely on the landline to call for help.

Why full fibre needs an installation at all

Older broadband arrives over the copper phone line that is already in your home, so switching provider often needs nothing more than a new router in the post. Full fibre is a different cable. A strand of glass has to be brought from the street to your property and terminated indoors. That is a one-off job. Once it is done, changing provider on the same network later usually needs no further visit.

If you are unsure what distinguishes full fibre from the "fibre" you may have now, full fibre broadband explained covers it.

The process below follows Openreach's published guidance, because its network is the largest. Virgin Media, CityFibre and the smaller networks each use their own engineers and equipment, but the steps are much the same. Your provider will tell you which network you are being connected to. Who provides fibre broadband in the UK explains how the networks and providers fit together.

Before installation day

From order to appointment

You order from a retail provider, not from the network. The provider agrees an installation date with you and confirms it in writing.
A survey may come first. If your property has unusual access, such as a long private drive, a shared entrance or a listed building, the network may send someone to plan the route before the main visit.
You receive reminders. Texts or emails arrive before the day, from your provider or the network. If you need to change the date, follow the instructions in those messages.
The router is delivered. It may arrive by post before the visit or come with the engineer. Leave it boxed until the fibre is in.

Remember that you have 14 calendar days to cancel a new broadband contract. If the installation has already taken place, you may have to pay for the service used and any installation cost.

How to prepare

Decide where you want the equipment. See the section on placement below. The engineer will advise, but it is your home and your decision.
Clear the way. Move furniture from the wall where the cable will enter, and make sure the engineer can reach the outside wall, including any side gate.
Check for a spare double socket close to your chosen spot. The ONT and the router each need a plug.
Arrange for an adult to be in. Openreach asks for a decision maker over 18 to be present for the entire appointment slot.
Get permission if the property is not yours. Openreach's guidance is clear that tenants should have the landlord's agreement for any drilling, inside or out. More on this below.
Tell your provider about anything connected to the phone line. That includes personal alarms and pendants, burglar alarms that dial out, and older payment or fax equipment.
Think about pets and parking. The engineer will be going in and out, and needs somewhere to leave a van.

What happens on installation day

Arrival

The engineer normally phones ahead with an arrival time. Once there, they walk the route with you: where the fibre will come from, where it will meet the house, and where it will go inside. They agree with you where the entry hole will be drilled. If digging or drilling is needed, you will be asked to sign a permission-to-work form.

Outside

Fibre reaches your home one of two ways:

Overhead, from a telegraph pole, following the same path as the old phone line.
Underground, through a duct from a chamber in the pavement.

Either way, the cable ends at a small junction box fixed to an outside wall. Openreach describes it as roughly 15 cm by 13 cm. If the engineer needs to secure a ladder, they may drill small holes in the wall for safety anchors, which are filled afterwards.

Inside

A cable is passed through the wall from the junction box to the ONT, a small white box mounted on the inside wall. The engineer connects the ONT to your router, powers both up, and checks the service is working on one of your devices before leaving.

How long it takes, and when it takes longer

Openreach says a standard installation usually takes around four hours. Some are quicker.

A minority cannot be completed in one visit. Typical reasons are a blocked or collapsed underground duct, a route that crosses someone else's land, a need for traffic management to work in the road, or bad weather that makes pole work unsafe. Openreach says a return visit is needed in only a small number of cases. If it happens, the engineer will explain what is required, and your provider, not the network, is your point of contact for the new date.

For context, BT Group reported that Openreach completed 90.5% of full fibre installations on time in the half year to 30 September 2026.

If the engineer does not turn up

If your provider is signed up to Ofcom's automatic compensation scheme, a missed appointment, or one cancelled with less than 24 hours' notice, earns you £32.31. If the service does not start on the promised date, you are due £6.46 for each day of delay. Those amounts apply from 1 April 2026. How to choose and switch broadband explains the scheme and lists the providers in it.

The equipment: what each box does

Item	What it is	Who supplies it	Needs mains power?
External junction box	A small weatherproof box on the outside wall where the fibre from the street is joined to the cable going indoors	The network	No
ONT (optical network terminal)	A small white box on an inside wall. It converts the light signal in the fibre into a standard network connection	The network; it stays with the property	Yes
Router	Shares the connection around your home by Wi-Fi and by cable. Plugs into the ONT	Your provider (you can often use your own)	Yes
Mesh units or extenders	Extra boxes that spread Wi-Fi to distant rooms	Your provider, or bought separately	Yes
Digital phone adaptor	Lets a traditional handset work through the router, where the router has no phone socket	Your provider, if needed	Yes
Battery back-up unit	Keeps the ONT and router running for a period during a power cut	Your provider, free if you qualify	Charges from the mains

A few points people often ask about:

The ONT is sometimes called a modem. It does a similar job. It has no Wi-Fi of its own.
The ONT belongs to the network, not to you or your provider. If you change provider on the same network, it stays on the wall and the new router plugs into it. If you move to a different network, that network fits its own.
On some networks the ONT and router are combined in one unit. In that case you will see a single box.
The very fastest packages may need a newer ONT. If you later upgrade to a multi-gigabit tier, a swap may be required.
Your old phone socket is left in place but is no longer used for broadband. Do not plug the new router into it.

Where to put the ONT and router

This is the most consequential choice you make on the day, and the one people most often leave to chance. The engineer's quickest option is to put the ONT just inside the wall where the cable enters, which is often a front corner of the house. The router then sits next to it. If that corner is far from where you use the internet, your Wi-Fi starts at a disadvantage.

Ofcom's guidance on Wi-Fi is that a router works best when it is:

central in the home, so the signal has less distance and fewer walls to cross
raised off the floor, on a shelf or table
in the open, away from radiators, water, metal and glass
away from sources of interference such as microwaves, cordless phones and baby monitors

Openreach makes the same point more bluntly: do not choose a dark cupboard under the stairs.

Practical ways to get a better position:

Ask whether the cable can enter at a different point. The fibre can often be run along an outside wall to come in nearer the middle of the house.
Ask how far the ONT can be from the entry point. There is some flexibility in the internal cable run.
Separate the ONT and the router. The two are joined by an ordinary network cable, which can be much longer than the short one supplied. The ONT can stay by the entry point while the router sits somewhere more central.
Plan for a mesh system if the house is large, has thick walls or spreads over three floors.

If you agree a position with the engineer and later wish you had not, moving an ONT usually means another visit and possibly a charge. It is worth ten minutes' thought beforehand.

Setting up your home Wi-Fi afterwards

Once the service is live:

Connect your devices to the new network. The network name and password are on a label on the router, often with a QR code you can scan with a phone camera.
Or keep your old Wi-Fi details. Ofcom notes you can set the new router to use your previous network name and password, so devices reconnect without being re-entered one by one. Only do this if the old password was a strong one.
Change the router's admin password from the default if your provider's instructions suggest it.
Wire what you can. A television, console or desktop computer near the router will do better on a network cable, and it frees up Wi-Fi for everything else.
Test the speed properly. Plug a computer into the router by cable and run a speed test, then test over Wi-Fi in the rooms you use most. If the wired result is good and a room is poor, the answer is better Wi-Fi coverage, not a faster package.
Return the old router if your previous provider asks for it. Some charge if you do not.

Our guide to broadband speeds explains how to read the results and what to do about weak spots.

Renting: do you need your landlord's permission?

For the first installation at a property, yes, in practice. The work involves fixing a box to the outside wall and drilling through it. That is an alteration to the building, and most tenancy agreements require consent for alterations. Openreach tells customers who rent to get the landlord's permission for any drilling.

As far as we could establish in November 2026, tenants have no specific legal right to insist on a full fibre installation. So the approach that works is a clear written request. It helps to tell the landlord:

what the work involves: one small external box, one hole, one small internal box
who does it and who pays: the network's own engineer, with standard installation usually covered by your package, not by the landlord
that it stays with the property, making it easier to let in future
that copper-based services are being withdrawn in areas where full fibre is widely available, so the property will need it eventually

Get the consent in writing, even by email, before the engineer arrives. If the property already has an ONT from a previous occupant, no new drilling is needed and you can usually order without asking.

Flats and leasehold properties

Flats are harder, because the cable has to pass through parts of the building nobody living there owns: risers, corridors, basements, the roof. Before a network can install in those shared areas, it needs a legal agreement with the building's owner called a wayleave. Until that is in place, the network may be in the street outside while every flat in the block shows as unavailable.

What you can do:

Find out who the freeholder or managing agent is and ask whether any network has approached them.
Register your interest with the networks serving your street. Demand from residents helps justify the work.
Get neighbours to ask too. A request from many flats carries more weight.
Raise it with your residents' association or at the building's annual meeting.

The law is moving in residents' favour, though slowly:

Already in force: the Telecommunications Infrastructure (Leasehold Property) Act 2021 lets a network operator apply for a court-imposed agreement where the owner of a block of flats repeatedly fails to respond to requests for access. That covers landlords who stay silent, not those who refuse.
Announced, not yet law when we checked: the government consulted between December 2025 and February 2026 on giving leaseholders in flats a right to request a gigabit-capable connection, with a duty on freeholders not to refuse unreasonably. On 13 May 2026 it confirmed the right would be included in its Commonhold and Leasehold Reform Bill, covering England and Wales. Check the Bill's progress for the current position.

Some networks specialise in flats and negotiate building-wide agreements with owners, wiring every flat at once. New-build homes should not face this problem: building regulations in England now generally require new homes to be built with gigabit-ready infrastructure.

A worked example: a house and a flat

A house you own. You order on a Monday and are offered an appointment nine days later. You decide the router should go in the hallway, which is central, and check there is a double socket. The engineer arrives, agrees to run the fibre from the pole to the front wall and then along under the eaves to enter by the hall. The junction box goes outside, the ONT goes inside above the skirting board, and three and a half hours later you are online. The old phone socket in the front room is left alone.

A rented flat in a converted building. You check your address and find full fibre shown as available. You email your landlord, who agrees to the drilling but points out that the building's freeholder controls the communal hallway. The network's checker shows the building as ready, which means a wayleave is already in place and equipment has been fitted in the communal area. The engineer runs a cable from that point to your flat, fits the ONT just inside your front door, and you place the router further in using a longer network cable. Had the building not been wired, the first step would have been the freeholder, not the provider.

What happens to your landline

The old phone network is being retired

Traditional landlines send calls as analogue signals over copper wires, using a system called the public switched telephone network, or PSTN. It is old, increasingly fault-prone and expensive to maintain. The industry is replacing it with digital landlines, where calls travel over your broadband connection. You may see this called Digital Voice, VoIP or an IP phone line.

BT plans to retire its old network by 31 January 2027. Customers on the Openreach network should be moved to a digital landline or an equivalent by then. The original target was the end of 2025.
Virgin Media O2 and KCOM also plan to retire their old phone networks. Ofcom said no dates had been set when we checked.
The government told Parliament that 3.6 million lines were still on the old network at 31 December 2025.

This change is happening regardless of what broadband you have. But with full fibre there is no copper line at all, so if you want a home phone it will be a digital one from day one.

What changes for you

Your handset plugs into the router, or into an adaptor supplied by your provider, instead of the wall socket.
You can normally keep your number.
The phone works over a broadband connection. If you want a landline but not internet access, ask your provider what it offers.
Extension sockets around the house may stop working, because they are wired to the old line. Cordless phones with several handsets are the simple answer.
You may not need a landline at all. Many households now take broadband only. If you do want one, say so when you order.

Power cuts

A digital landline needs mains electricity at the ONT and the router. In a power cut, it stops working unless there is back-up power.

Ofcom's rules address this directly:

If you depend on your landline, for example because you have no mobile or no reliable mobile signal at home, your provider must offer you a free back-up solution, such as a battery unit.
The back-up must last at least one hour. Some providers supply units lasting up to seven hours.
For most people, a charged mobile phone is the practical fallback. A 999 call from a mobile can connect through any available network, even if your own has no signal.

Telecare, alarms and anything else on the line

Devices that dial out over the phone line may not work properly on a digital landline. That includes fall detectors and care pendants, some burglar and fire alarms, and older lift alarms.

Tell your landline provider and the device supplier before any change. Providers must assess the needs of customers who need extra help and can pause a move until a safe arrangement is in place.
Tell them if you are elderly, disabled or have a health condition that makes the landline important, even if you have no alarm.
Respond when your provider contacts you about the switchover. Ignoring letters risks losing service.
Before buying any new device that uses the phone line, check with the manufacturer that it works on digital lines.

Providers have signed government-backed charters, updated in March 2026, committing them to protect vulnerable customers during the change. If you are arranging full fibre for an older relative, raising the telecare question at the point of ordering is the single most useful thing you can do.

Installation checklist

Before the day

Appointment confirmed in writing
Equipment position chosen, with a double socket nearby
Landlord or freeholder consent obtained, in writing, if needed
Provider told about any alarm, pendant or dependence on the landline
Access cleared indoors and outdoors
An adult available for the whole slot

On the day

Route and entry point agreed with the engineer before work starts
ONT and router positioned where you want them
Service tested on your own device before the engineer leaves
Landline tested, if you have one

Afterwards

Devices reconnected; Wi-Fi checked in each room
Wired speed test run and compared with the estimate you were given
Old router returned if required
First bill checked against your contract summary

Frequently asked questions

How long does a full fibre installation take?

Openreach says around four hours for a standard installation. Simple jobs are quicker. A small number need a second visit, for example where an underground duct is blocked.

Do I need to be at home?

Yes. Someone aged 18 or over, who can make decisions about where cables and boxes go, has to be present for the whole appointment.

What is an ONT?

An optical network terminal. It is a small box fitted to an inside wall where the fibre optic cable ends. It converts the light signal into a connection your router can use, and it needs mains power.

Will the engineer drill holes in my wall?

Usually one hole through an outside wall to bring the cable in, plus fixings for the two small boxes. You agree the position first. If you rent, get the landlord's permission.

Is there a charge for installation?

It depends on the provider and package. Many deals include standard installation, while some charge a set-up fee. Non-standard work, such as a very long cable route across private land, can cost extra. Check your contract summary.

Can I choose where the router goes?

Within limits, yes. The ONT needs to be reasonably near the point where the cable enters, but the router can be placed further away using a longer network cable. A central, open position gives the best Wi-Fi.

Does my landlord have to let me have full fibre?

As far as we could confirm in November 2026, there is no specific legal right for tenants to require it. Most landlords agree when asked, since the work is minor and adds value. Ask in writing and keep the reply.

Why can't my flat get full fibre when the street has it?

The network probably lacks the building owner's permission, called a wayleave, to install in shared areas. Contact the freeholder or managing agent and register interest with the network.

Will my landline still work?

Yes, if you ask for one, but as a digital landline through the router. You can usually keep your number. It will not work in a power cut without battery back-up.

What happens to my personal alarm or telecare device?

It may not work on a digital line. Tell your broadband provider and the alarm supplier before installation. Providers must make suitable arrangements for customers who depend on such devices.

Sources

All sources accessed 13 November 2026.

General information for UK households, not legal or financial advice. Facts checked on 13 November 2026; prices, coverage and rules change, so confirm details with a provider before you sign up.