What is a Leased Line? The Complete UK Business Guide
Your business broadband works fine — until it doesn't. A busy Monday morning, a video call with a client, four colleagues all on the phone at once, and suddenly you're watching a loading spinner instead of running your business. A leased line exists to make that problem disappear entirely. This guide explains exactly what a leased line is, how it compares to standard broadband, what it costs in the UK right now, and which businesses genuinely need one.
The short answer: A leased line is a dedicated, symmetrical internet connection rented exclusively for your business. Unlike broadband, the bandwidth is not shared with other users — you get the full speed you pay for, every hour of every working day, backed by a contractual uptime guarantee. Prices start from £149/month for a 100Mbps circuit in most UK locations.
How a leased line works
Standard broadband — even "business" broadband — runs on a shared network. Dozens or hundreds of nearby businesses and homes use the same underlying infrastructure simultaneously. When everyone's online at once, the available bandwidth gets divided between them. You pay for "up to 100Mbps" and get considerably less at peak times.
A leased line is different in one fundamental way: the circuit is yours alone.
Your provider installs a dedicated fibre connection directly from your premises to the nearest point of presence on the carrier network. No sharing, no contention, no performance variation based on what the business next door is doing. The 500Mbps you pay for is 500Mbps at 9am on a Monday, at 3pm on a Wednesday, and at 11pm on a Friday.
The connection is also symmetrical — upload and download speeds are identical. For most broadband products, upload speeds lag significantly behind download speeds. For businesses making VoIP calls, transferring large files, running cloud applications, or backing up data remotely, symmetrical bandwidth matters.
Leased line vs broadband: the key differences
| Leased line | Business broadband | |
|---|---|---|
| Connection type | Dedicated | Shared (contended) |
| Speed consistency | Guaranteed | Variable — "up to" |
| Upload / download | Symmetrical | Asymmetric (upload much slower) |
| Uptime guarantee | 99.999% ("five nines") SLA | Best effort — no contractual guarantee |
| Fault repair time | Typically 4–5 hours, 24/7/365 | Working days — can take several days |
| Typical cost | From £149/month | From £30–£80/month |
| Contract length | 12–36 months | 12–24 months |
| Best for | High-dependence, cloud-heavy, VoIP | Light use, backup connectivity |
The practical gap between the two is widest when something goes wrong. A broadband fault is repaired on Openreach's schedule — which typically means next-business-day at best. A leased line SLA means an engineer is contractually required to fix the fault within a defined window, usually 4–5 hours, around the clock.
What "five nines" uptime actually means
The gold standard SLA for leased lines is 99.999% uptime — often called "five nines." That sounds abstract. In concrete terms, 99.999% uptime allows for just 26 seconds of unplanned downtime per month.
Standard business broadband carries no guaranteed uptime at all. Your provider will aim to keep the service running, but there is no contractual obligation about how long a fault takes to fix or what compensation you receive when it goes down.
For most businesses, the difference between 99.9% and 99.999% uptime sounds negligible. It isn't. 99.9% uptime allows for 8.7 hours of downtime per year. 99.999% allows for 5.3 minutes. If your business loses £500/hour when phones and internet go down, that gap represents a meaningful financial risk.
Leased line providers back their SLA with service credits — if they miss the target, you receive a credit against your bill. It is a contractual obligation, not a promise.
Who actually needs a leased line?
A leased line is not right for every business. Here are the scenarios where it makes clear commercial sense:
You run a cloud-based phone system (VoIP) VoIP calls are sensitive to network jitter, latency, and packet loss. On a contended broadband connection with variable performance, call quality drops — particularly during busy periods. A leased line eliminates this by guaranteeing consistent bandwidth. For a business where the phone is a revenue tool, not just a convenience, the call quality improvement alone often justifies the cost.
Your team works across cloud applications all day Businesses running Microsoft 365, Salesforce, Sage, or similar cloud platforms depend on a consistent, fast upload connection. If your broadband upload speed degrades during peak hours, your team works slower. A leased line means consistent performance regardless of time of day.
You process card payments or handle sensitive data PDQ terminals, card payment gateways, and any system subject to PCI-DSS compliance benefits from a dedicated, private connection. Many insurance and compliance frameworks now expect demonstrable connectivity resilience.
You cannot afford downtime A solicitors' firm mid-completion, a medical practice with electronic records, a contact centre taking calls — for these businesses, an hour offline is not an inconvenience, it is a crisis. A 4-hour SLA repair time and 99.999% uptime guarantee changes the risk profile significantly.
You have 10 or more staff online simultaneously With 10 people video calling, using cloud applications, and running VoIP simultaneously, a 100Mbps leased line starts making sense on bandwidth grounds alone — quite apart from the SLA benefits. As headcount grows, the contention on shared broadband becomes increasingly disruptive.
If your team is under five people and you mostly use email and light web browsing, standard business broadband is probably sufficient. If any of the above scenarios match your business, a leased line is worth pricing up.
How much does a leased line cost in the UK?
Leased line pricing in the UK has fallen significantly over the past five years — prices are down 30–40% since 2020 as more fibre carriers have expanded their regional networks. As of 2026, typical pricing looks like this:
| Bandwidth | Typical monthly cost (UK) |
|---|---|
| 100Mbps | £149–£320/month |
| 500Mbps | £250–£500/month |
| 1Gbps | £300–£900/month |
The exact cost for your business depends on three factors:
Location. Central London and major city centres have the most carrier competition and therefore the lowest prices. Rural and semi-rural locations may cost 30–50% more due to higher installation costs. Getting a quote for your specific postcode takes less than 10 minutes.
Contract length. Most leased lines are sold on 12, 24, or 36-month terms. Longer contracts carry lower monthly costs — a 36-month agreement typically saves 15–20% versus a 12-month equivalent.
Installation. Some providers include installation in the monthly rental; others charge a one-off installation fee ranging from £500 to several thousand pounds, depending on the distance from the nearest fibre point and whether civils work is required. Always ask whether the quote includes installation.
For a 10-person business on a 100Mbps leased line, the total annual cost is typically £1,800–£3,600 — less than the cost of one member of staff losing a week of productivity to connectivity problems each year.
Leased lines and VoIP: why the two work together
If your business is moving to VoIP — whether for cost reasons, because the 2027 PSTN switch-off is forcing the migration, or both — your internet connection becomes the backbone of your phone system.
Hosted VoIP uses approximately 100Kbps of bandwidth per active call. A team of 10 with five simultaneous calls needs 500Kbps dedicated to voice traffic — a small amount in raw terms, but quality depends on consistency as much as capacity. Jitter (variation in packet delivery timing) and latency (the delay between speaking and being heard) both degrade call quality, and both are symptoms of a congested shared network.
A leased line resolves this by design. Dedicated bandwidth means your VoIP traffic competes with nothing. Combined with quality-of-service (QoS) settings that prioritise voice packets, a leased line delivers call quality that matches or exceeds traditional ISDN — often at lower total cost when you factor in what you were paying per ISDN channel.
For businesses running on ISDN now, the 2027 PSTN switch-off makes this decision pressing. Migrating to VoIP on a leased line is the straightforward, future-proof path: you replace the old copper with a modern IP connection, move to hosted VoIP, and end up with a better phone system at a lower monthly cost than your current ISDN spend.
How VoIPninjas delivers leased lines
VoIPninjas is a direct UK provider — not a reseller — based in Christchurch on the South Coast. Our leased lines start from £149/month and are supplied on 28-day evergreen agreements alongside our VoIP plans, so you get your connectivity and your phone system from a single provider with a single support number.
Because we own our infrastructure, support calls go directly to the team who can act on them — not to a call centre that escalates to a third party. For businesses in Dorset, Hampshire, and the Channel Islands, we can also provide on-site support when the situation calls for it.
A combined leased line and VoIP setup with VoIPninjas typically looks like this:
- 100Mbps dedicated leased line from £149/month
- VoIPninjas Samurai for your team at £14.99/user/month (750 min/month, full feature set)
- Number porting included — you keep every existing business number
- Most businesses are fully live within 10 working days
That is a complete, future-proof business communications stack. No PSTN dependency, no shared broadband risk, no 24-month lock-in with a provider you cannot reach when something goes wrong.
Get a quote for a leased line and VoIP package No tie-in, no setup fees. Most businesses are fully live within 10 working days. Get a Free Quote — or call us: 0330 043 2388
Frequently asked questions
What is the difference between a leased line and fibre broadband?
Both use fibre optic infrastructure, but the connection model is completely different. Fibre broadband — including full-fibre FTTP products — runs on a shared network. Multiple businesses and homes use the same underlying infrastructure simultaneously, so speeds vary. A leased line is a dedicated circuit used by your business alone, with guaranteed speeds and an uptime SLA. You pay more, but you get a contractual guarantee rather than a best-effort service.
How long does leased line installation take?
Installation typically takes 30–90 days from order to go-live, depending on your location and whether Openreach or alternative carriers already have fibre close to your premises. Rural locations occasionally take longer if civils work is required. Your provider will give a firm estimated delivery date at quotation stage.
Do I need a leased line to run VoIP?
Not always — many businesses run excellent VoIP systems on standard FTTC or FTTP broadband. The case for a leased line becomes stronger as your team size grows, as your call volume increases, or if you need guaranteed uptime for compliance or operational reasons. If your current broadband connection is stable and fast, test VoIP on it first before committing to a leased line. VoIPninjas' free 14-day trial lets you do exactly that.
Can I get a leased line outside of a city?
Yes, though rural pricing is higher due to greater infrastructure costs. If your premises are a long distance from the nearest fibre point of presence, your provider may require a contribution to civils costs. Pricing for your specific postcode requires a quote — ballpark estimates are rarely accurate for rural locations.
Is a leased line the same as a private circuit?
The terms are often used interchangeably. A leased line (or Ethernet leased line) provides dedicated connectivity between your premises and the internet — it is a private connection in the sense that no one else shares your bandwidth. A private circuit can also refer to a point-to-point connection between two of your own sites (rather than to the internet), sometimes called an Ethernet private line or EFM circuit. If you are connecting two offices together, specify which type you need when requesting quotes.
What happens if my leased line goes down?
Your SLA defines the response and repair commitment. Most leased line SLAs guarantee a fault repair within 4–5 hours, 24 hours a day, 7 days a week. If your provider misses the SLA target, you receive service credits. For businesses with VoIP, a leased line failure means your phone system depends on a backup route — either a 4G failover connection or a secondary broadband line. VoIPninjas can advise on failover options at quotation stage.