CONNECTIVITY · GUIDES
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26 May 2026
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4 min read
Leased line vs full fibre: which is right for your business?
Leased lines and full fibre are both fast, reliable connectivity options. But they are very different products. Here is how to decide which one your business actually needs.
Both leased lines and full fibre broadband offer significantly better performance than standard ADSL or FTTC broadband. Both use fibre optic infrastructure. Both are available to businesses across most of the UK. And both are frequently recommended by connectivity providers without a clear explanation of how they differ or which one is actually right for a given business.
LEASED LINES
A private, dedicated circuit that belongs entirely to your business
A leased line is a point-to-point connection between your premises and the internet that is dedicated entirely to your business. The bandwidth is uncontended, meaning it is never shared with other users. Speeds are symmetric, meaning upload and download are equal. And the connection comes with a contractual uptime SLA, typically 99.98% or above, backed by a network operations centre that monitors it around the clock.
Leased lines are installed by an engineer, involve physical infrastructure work, and typically carry lead times of four to twelve weeks. They are priced at a premium compared to broadband products, and they are worth it for businesses where connectivity is genuinely mission-critical.
FULL FIBRE
A pure fibre broadband connection from the exchange to your door
Full fibre broadband, also known as FTTP or fibre to the premises, replaces the copper wire used in standard broadband with a pure fibre connection all the way from the exchange to your building. The result is significantly faster speeds and lower latency than copper-based broadband, with greater reliability over distance.
Unlike a leased line, full fibre is a shared access product. Your connection runs on a shared network, and while contention ratios are typically low on business-grade full fibre products, the bandwidth is not exclusively yours. SLAs are typically lower than those available on leased lines, usually around 99.8%.
THE KEY DIFFERENCES
Four things that separate them
Contention. A leased line is uncontended. Your bandwidth belongs to you and nobody else. Full fibre operates on a shared network. For most businesses the difference in practice is negligible, but for businesses with very high or consistent bandwidth demands it matters.
SLA. Leased lines carry a 99.98% uptime SLA. ATN's full fibre product carries a 99.8% SLA. The difference translates to roughly 14 hours of additional permitted downtime per year compared to a leased line. For businesses processing high volumes of transactions or running time-sensitive operations, that gap is meaningful.
Speed symmetry. Leased lines offer equal upload and download speeds. Full fibre products vary. If your business regularly uploads large files, runs hosted services, or uses VoIP at scale, symmetric speeds matter.
Cost and lead time. Full fibre is less expensive and faster to install. A leased line costs more and takes longer to commission. The premium reflects the dedicated infrastructure and higher SLA commitment.
WHICH ONE IS RIGHT FOR YOU
The questions worth asking
Choose full fibre if your business needs a significant upgrade from standard broadband, your budget does not stretch to a leased line, your connectivity needs are moderate, and occasional brief degradations would not have a serious operational impact.
Choose a leased line if your business cannot afford unplanned downtime, you run payment systems, hosted services, or cloud-dependent operations that require consistent performance, you need symmetric upload and download speeds, or you are connecting multiple sites that each require a guaranteed service level.
Some businesses start on full fibre and upgrade to a leased line as they grow. The important thing is to choose the product that matches your current needs and build in a review point as your requirements change.
WHAT GOOD LOOKS LIKE
The right answer depends on your business, not on what is easiest to sell.
A provider worth working with will tell you honestly which product fits your situation, even if it is the less expensive one. At ATN Communications, we offer both. If you tell us about your business, we will tell you which one makes sense.
MORE FROM THE BLOG
Keep reading
Not sure which product is right for your business?
Talk to ATN and get a straight answer. We offer both leased lines and full fibre.
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