In short
The difference between a leased line and broadband is sharing. Broadband shares network capacity between customers, usually has a lower upload speed and is sold on a best-efforts basis. A leased line such as BTnet is dedicated and uncontended, has the same speed up and down, and comes with service levels and service credits in the contract.
Not sure which suits you?
Tell us about your sites and how you use the internet and we will explain whether it fits, and why.
Leased line vs broadband at a glance
This is a comparison of two technologies, not of providers. The right-hand column describes BTnet under BT's terms.
| Business broadband | Leased line (BTnet) | |
|---|---|---|
| Capacity | Shared with other customers further into the network | Dedicated access line; BT describes BTnet as 100% uncontended |
| Upload vs download | Upload is often lower than download | Symmetrical: the same speed both ways |
| Speed at busy times | Can drop when the shared network is busy | The port speed is reserved for you |
| Service levels | Usually best efforts | BT's SLA: availability, on-time delivery and latency, with service credits |
| Data allowance | Varies by package | No fair usage policy, according to BT |
| IP addresses | Varies by package | Static IPv4 addresses as standard |
| Installation | Usually quicker, often over existing lines | Survey first; BT says up to 70 working days, survey dependent |
| Contract | Varies by package | A minimum period set in the order, with termination charges |
| Cost | Lower | Higher; priced for your site. Ask us for a quote |
The detail behind each row is below.
Still not sure? Ask us
Tell us what matters most to you and we will explain the trade-offs.
Shared vs dedicated capacity
Broadband connects many customers to shared equipment and links. Most of the time there is enough capacity for everyone, but at busy times users compete for it and speeds fall. That sharing is called contention, and it is what keeps broadband affordable.
A leased line removes the sharing. Your site has its own access line into the provider's network and the bandwidth you buy is reserved for you. BT's terms list uncontended, symmetrical bandwidth as a standard part of BTnet, and BT's help pages describe the service as 100% uncontended and dedicated. In practice that means the speed you see at 9am on a Monday should look like the speed you see at 9pm on a Sunday. Read contended vs uncontended for more.
Upload speed
Many broadband services, including many full fibre packages, give a higher download speed than upload speed. That suited the days when businesses mainly downloaded web pages and email. Today, video meetings, cloud file sync, offsite backup, CCTV and hosted phone systems all send a lot of data out of the building, and a low upload speed becomes the bottleneck.
BTnet bandwidth is symmetrical, so a 100Mbps BTnet service gives 100Mbps in each direction, and BT offers speeds up to 10Gbps upload and download. See symmetrical internet speeds for why upload matters, with a worked example.
Weighing it up?
We can look at your sites and requirements and give you a straight answer.
Service levels and support
Broadband is usually sold on a best-efforts basis: the provider aims to deliver a speed and fix faults, but does not normally commit to availability with service credits. A leased line is a contracted service with commitments written into the terms.
For BTnet, BT's SLA includes:
- Availability: a 100% availability service level (excluding Wi-Fi), with credits of one day's rental for each hour of downtime, capped at 10 hours a quarter
- On-time delivery: credits against the connection charges if BT misses the Customer Committed Date, rising with the number of working days late
- Latency: an average round trip of 20ms or less on BT's UK core network and 95ms or less transatlantic, measured over a calendar month
Claims have conditions and deadlines. The BTnet SLA page explains them, and BT leased line support covers how faults are reported under BT's Business Premium Care support level.
Installation and contract
Broadband usually goes live quickly because it often reuses lines already in the building. A leased line is built for your site: BT arranges a survey, may need extra construction or a wayleave from your landlord, and gives a Customer Committed Date once the survey is done. BT's help pages say BTnet can take up to 70 working days, depending on the survey. See lead times.
Contracts differ too. BTnet has a Minimum Period of Service set in the order; BT's terms refer to three- and five-year contracts. Ending early carries termination charges under BT's terms, which our BTnet contract terms page explains in plain words. Plan the switch well before any broadband contract ends or an office move.
When broadband is enough
Broadband is a sensible choice for plenty of businesses, and we would rather you buy the right thing. It is often enough when:
- A small team mainly uses email, web browsing and a few cloud apps
- Only one or two people are on video calls at once
- Short slowdowns at busy times are an annoyance rather than a cost
- Nobody needs to upload large files, backups or camera footage regularly
- You need to be online within days rather than weeks
When it is time to move to a leased line
Consider BTnet when the connection has become something the whole business depends on:
- Calls and video meetings break up when several people use them at once, especially if you are moving to cloud calling such as BT Cloud Voice
- Your team works in Microsoft 365 and cloud apps all day
- Backups, file sync or CCTV need steady upload
- Downtime costs money: lost sales, idle staff, missed calls
- You need static IP addresses for VPNs, remote access or supplier allow-lists
- You are adding people, sites or systems and need room to grow with Bandwidth Flex
A leased line still has a single path into the building. If you cannot afford any downtime, plan resilience with a second BTnet access line from the start.
Not sure which you need?
Forever Communications is an Authorised Supplier for BT, so we can look at how your business uses its connection today, what is changing, and whether a leased line is justified. If it is, we can help you choose the speed, plan and options and prepare a BTnet quote; if broadband is still enough, we can tell you that too. Contact us with your postcode and a few lines about your site. You might also find our bandwidth sizing guide and advantages and disadvantages of a leased line useful.
Why buy BTnet from Forever Communications
Forever Communications is part of Forever Group and an Authorised Supplier for BT. We supply BTnet, BT's dedicated leased line internet service, to businesses, schools, charities and public sector organisations, and we help with each step from first enquiry to go-live.
- The right BTnet option for you: we help you choose a speed, bearer, router and resilience option that fits how your sites actually work, from BTnet plans to BTnet speeds
- A clear quote: BTnet is priced per site, so we check availability at your address and set out what is included; see leased line cost
- Installation managed with you: we explain the survey, any wayleave or construction steps and the installation process, and keep you updated on progress
- Connected services in one conversation: phones with BT Cloud Voice, Wi-Fi, firewalls and backup lines, so the whole set-up is planned together
- Help after go-live: we can help with faults, changes and upgrades, with the support arrangements confirmed in your quote
BTnet is a business service. Service levels, lead times and features are BT's and are confirmed at order.
Frequently asked questions
What is the main difference between a leased line and broadband?
A leased line is dedicated to your site and symmetrical, with service levels in the contract. Broadband shares capacity between customers, usually has a lower upload speed and is normally best efforts.
Is a leased line faster than broadband?
Not necessarily on paper, because some broadband packages advertise high download speeds. The difference is that a leased line's speed is reserved for you, the same in both directions, and backed by service levels.
Is a leased line more reliable than broadband?
A leased line is uncontended and comes with BT's SLA, including a 100% availability service level with service credits. A single line can still fail, so businesses that need more add a second line for resilience.
Why does a leased line take longer to install than broadband?
A leased line is built for your site. It needs a survey, sometimes new construction or a landlord's wayleave, and BT says installation can take up to 70 working days depending on the survey.
Can I keep broadband as a backup to a leased line?
BT's resilience options for BTnet add a second access line to the same BTnet service, set up as failover, load balancing or a lower-speed back-up. Which options are available depends on your configuration, speed and location, and is confirmed at quote. Ask us which suits your site, and see resilient BTnet.
Still deciding?
Ask us and we will reply by email with a straight answer.