What is a leased line? 

10 November 2025 

What is a leased line?

Whether you’re looking to migrate your services to the cloud or just looking to provide your business with the absolute best Internet connectivity possible, you’re more than likely going to be considering a leased line as one of your options. 

You might be wondering what exactly you’re getting for your money, and how a leased line might suit your business better than a standard broadband offering…

Here, EPX’s 'Professor' Elliot brings you up to speed on some of the fastest fixed connections money can buy.

Broadband Line

We’ll start by breaking down the anatomy of a typical broadband line. Times have moved on for those of you who might remember the screech of dial-up connections from the 90s and noughties, and technically speaking, even terms such as “ADSL” are behind us. 

As of 2023, it’s not been possible to buy a broadband service based on the UK’s traditional copper-cabled landline telephone network, and as of January 2027, BT Openreach will be switching the landline network off completely. 

If you last switched broadband providers before 2023, don’t panic – your provider has almost certainly been in touch with you about this in one form or another and depending on who supplies your current connection, you may not need to do anything, or you may need to order a new service that doesn’t rely on this old-school tech.

Replacement to ADSL broadband

The direct replacement to ADSL broadband is referred to as Single-order General Ethernet Access, shortened to “SoGEA”. The underlying infrastructure (or at least, the part that runs from the exchange, the green or grey cabinet at the end of your street, to your house) is still usually copper, so the speeds you can expect to get are still roughly in line with ADSL, usually capping at around 80 Mbps download and 20 Mbps upload. This difference in speeds is where the “A” in “ADSL” comes from – asynchronous. 

Your ISP is essentially betting that you’ll download more content from the Internet than you’ll upload to it, and in 99% of cases, this is probably true – most of us probably watch Netflix but don’t regularly make and upload YouTube videos, for instance. Providing you with a different speed in each direction helps the ISP to load balance your connection and maintain a consistent level of service for you and your neighbours – more on this later…

You won’t be left without the option to make phone calls when making the switch to a SoGEA line, but your landline won’t work in quite the same way – instead of using the old-fashioned phone network, phones on a SoGEA line instead have to run directly over the Internet – this is called “Voice over IP” or “VoIP”, and many business phone systems already use this same technology. This is optional, but if you do choose to include a phone number as part of your service, you’ll likely be provided with a basic VoIP-capable handset, along with your router.

Fibre

The next tier of connection is Fibre, sometimes called “Full” Fibre to highlight that the fibre optic cables this type of connection runs over lead all the way to your house, not just the exchange. Instead of electrical signals, data on a fibre connection is transmitted as pulses of light, which travel much faster and can support faster speeds.Fibre connections typically start out around 150 Mbps down, and can go up to and even surpass 1 Gbps, though they usually still maintain the same asynchronous upload speed for load balancing. 

As the tech in our homes and offices predominantly still use electrical signals, though, you’ll need a special device installing to convert the light pulses back into electrical ones – this is called an “Optical Network Terminal”, or “ONT”, and will be installed for you either for free or with a slight charge by the ISP’s engineer before your service goes live.

A leased line

But what if you need more than just a fast connection? What if you need a guarantee that your speeds won’t drop below a certain threshold, or that you won’t lose connection altogether? This is where leased lines come in – a leased line is a special type of connection, usually based on fibre, that can address these concerns in a way that standard connections simply can’t.

On a regular SoGEA or Fibre service, you might have noticed that, at peak times when more people are at home using their broadband, such as prime time in the evenings, your speed might drop. Suddenly, you’re sat looking at a “Buffering” icon instead of watching your favourite show – why is this? 

Well, remember that the reason for your asynchronous download and upload speeds is in the interest of load balancing – you can think of the cable that leads down your street from the exchange cabinet as a tree, with each home being supplied by a “branch” of this tree. The “trunk” is therefore being shared by everyone on your street, and will be able to support a maximum amount of traffic at once. If everyone’s trying to catch up with the latest episode at the same time, then you might find that some or all of these shared connections have to be limited, or “throttled” to ensure that everyone still gets at least some of the bandwidth – it’s only fair to share. 

In other words, your neighbours being at home or not might be the difference between a smooth viewing experience and being stuck in “buffering” hell. 

Leased line benefits

Leased lines don’t have this problem – a leased line is like having your own private lane, that supplies your home or business only. 

The level of usage for other businesses in the area has almost no effect on your connection, making it more stable and reliable. You’ll likely have the same upload speed as your download speed, as there’s no reason to load balance your connection with others – this is especially important for any business using cloud-based solutions, where uploading files to, say, SharePoint, happens just as often as downloading them.

Your ISP might be able to guarantee that your speeds won’t drop below a certain point, and typically, leased lines are rated for 99.99% uptime or better, referred to as “four nines” – crunching the numbers, this amounts to less than an hour of downtime per year! All of the advantages of full-speed fibre with none of the drawbacks of sharing with the neighbours.

The catch

There is only one catch – because the ISP can’t utilise any of the bandwidth you’re not actively using for anyone else, there is a premium attached to leased lines that make them more expensive than an equivalent speed fibre connection. 

Probably not worth it for your evening’s entertainment, but for keeping your office online and working at peak productivity, there’s no better solution that money can buy. Considering your options?If leased lines have piqued your interest, or if you want to make sure you’re sorted before the switch-off in January 2027, speak to one of our Partner Success team on 01785 332977.