What Is a Leased Line? A Plain-English Guide for UK Businesses

A leased line goes by several names — Ethernet leased line, dedicated internet access (DIA), or private circuit — but the principle never changes. A dedicated fibre runs point-to-point from your premises to the carrier's network, then to the internet. That path is yours. Nobody else's traffic touches it, so the speed you buy is the speed you get, every hour of every day.

How is a leased line different from business broadband?

A leased line is dedicated and uncontended; broadband is shared. With broadband, many homes and businesses use the same exchange infrastructure at once, so your real-world speed drops when the network is busy. A leased line removes that contention entirely and adds symmetric speed, static IPs and a hard SLA.

The differences go well beyond headline speed. Each one maps to a day-to-day operational outcome:

For context, Ofcom's UK Home Broadband Performance reporting put the UK average broadband download speed at 69.4 Mbps in 2024. That number is an average of a shared, asymmetric service — upload speeds on FTTC broadband are often only 10–20 Mbps regardless of download, which throttles VoIP, video calls and cloud backup. A leased line gives equal upload, so those workloads stop fighting for headroom.

What types of leased line can UK businesses buy?

There are three main leased line types in the UK, and the right one depends on budget, location and bandwidth. Most SMEs buy an Ethernet Access Direct circuit; some choose a lower-cost FTTC variant; a minority of large sites take dark fibre and run their own electronics.

• Ethernet Access Direct (EAD): A full dedicated fibre from your premises to the carrier exchange, available from 100 Mbps to 100 Gbps. This is what most businesses mean by "a leased line".
• Ethernet over FTTC (EoFTTC): Uses existing FTTC infrastructure but delivers a dedicated, uncontended service. Cheaper than full EAD, with lower top speeds — a sensible middle tier when broadband isn't reliable enough but a full circuit isn't justified.
• Dark fibre: An unlit fibre pair where you provide the active equipment. Used by larger organisations with very high bandwidth or specialist routing needs.

If your priority is fast deployment over a guaranteed dedicated path, an FTTP leased line can be a strong middle ground in areas where full-fibre is already built.

What speed of leased line does your business need?

Leased lines run from 100 Mbps to 100 Gbps, but most UK SMEs sit at 100 Mbps, 500 Mbps or 1 Gbps. The right figure depends on user count, how cloud-heavy your workloads are, and whether you host services others connect into. Because the line is symmetric, upload capacity matters as much as download.

Symmetric upload is the quiet differentiator. Businesses backing up to the cloud or running hosted phone systems feel it immediately — a busy call queue or a nightly backup no longer collides with everyone else's traffic. Ofcom's Connected Nations reporting shows roughly 96% of UK premises can now get superfast broadband of 30 Mbps or more (Ofcom, 2024), yet that headline still hides weak, asymmetric upload — which is exactly where a leased line wins.

How much does a leased line cost in the UK?

UK leased line pricing is driven mainly by distance from your premises to the nearest carrier point of presence, then by speed and contract term. Urban sites near existing fibre are cheapest; rural sites can carry excess construction charges. As a current guide:

Prices are usually quoted on 36-month terms; shorter terms cost more per month. Installation can be zero on well-served business parks or significant where new fibre must be dug. AMVIA compares quotes from multiple carriers for your exact postcode rather than pushing a single network, so the figure you see reflects what's genuinely buildable at your site.

How long does leased line installation take?

Leased line installation typically takes 30 to 90 days from order to go-live. The biggest variable is civil engineering: how far new fibre must be laid and whether the route crosses third-party land needing wayleave agreements. City-centre and business-park sites with nearby infrastructure land at the short end of that range.

The stages are predictable: site survey, fibre route planning, any wayleaves, civil works, then installation of the network termination equipment inside your building. Because timelines swing on groundwork, we advise starting procurement at least 60 days before your required go-live date. If a critical cutover is looming, that lead time is the difference between a calm migration and an emergency.

What uptime does a leased line SLA guarantee?

A leased line SLA typically guarantees 99.9% or higher availability — under nine hours of unplanned downtime a year — with the strongest tiers at 99.99% (under an hour). Crucially, leased line SLAs are backed by financial compensation when targets are missed, unlike the best-efforts SLAs that come with broadband.

Just as important are the response and fix targets. A standard business leased line usually carries a four-hour response and a next-business-day fix; enhanced SLAs offer four-hour fix guarantees for businesses where an outage costs real money by the hour. For sites that cannot tolerate any downtime, a leased line is often paired with backup connectivity so a second, diverse path takes over automatically.

Which businesses actually need a leased line?

A leased line suits any business where reliable, high-performance connectivity is operationally critical. Clear signals include 20+ staff on one connection, heavy use of Microsoft 365 or cloud ERP, on-site or hosted servers reached over VPN, daily video conferencing, or a contractual requirement for guaranteed bandwidth and an SLA.

If you run several offices, the line rarely sits alone — it becomes the backbone for multi-site connectivity, often wrapped in SD-WAN to route traffic intelligently between sites and the cloud. For smaller firms not yet at that threshold, full-fibre broadband can be a sensible interim step. Ofcom's Connected Nations data shows gigabit-capable coverage now reaches the large majority of UK premises — but coverage is not the same as a guaranteed, contended-free service, and that distinction is the whole point of a leased line. AMVIA advises honestly on which side of that line your business sits.