Leased Lines

The Definitive Business Guide

leased line

What This Leased Line Guide Is About


You may or may not be familiar with the term leased line. If you aren't don't worry, this guide to leased lines will reveal all. If you are familiar with leased lines we'll go into detail about all aspects including, how leased lines work, how much they cost, what impacts cost, the cheapest providers, the shortest lead times, the most reliable networks, coverage and much, much, more. If you wish you can navigate to the relevant sections using the shortcuts below.

leased lines
Key Facts

Leased lines speeds range from 2 Mbps to 10 Gbps.

V.E.N have the fastest lead times and Vodafone the slowest lead times.

BT have the lowest instances of excess construction charges, Virgin Media have the highest.


Leased Line Costs

Leased line costs range from £149/month to over £5000/month. The price is mainly determined by 4 factors: the speed of bandwidth, the bearer size, the location of your business and the number of competing providers.

Leased Line Introduction A Leased Line Overview Powered by Amvia

The technical definition of a leased line, is a dedicated, symmetric, fibre telecommunications circuit. 


Diagram: Components Of A Leased Line


Not sure what dedicated and symmetric mean or why they are useful attributes of a leased line? Don't worry! You can check out a more detailed description of these technical phrases below.



Dedicated means that the leased line service is not shared. Some other broadband services are shared and slow down at busy times e.g. lunchtime. A dedicated service does not slow down if other businesses are using the internet ecessively.


 You may have heard the phrase uncontended. This is a technical term which means dedicated too. The leased line is for your use only, it's a bit like having your own road to work which you can be sure won't have any traffic at rush hour.



Symmetric means that the leased line has the same upload and download speed. For example 100 Mbps upload / 100 Mbps download. Other broadband services have asymmetric properties which means the upload and download speeds are different. For example FTTP can have 80 Mbps download / 20 Mbps upload.

Symmetric bandwidth can be very useful because you can upload as fast as you can download. This means it will speed up cloud applications such as CRM, make sending large files faster, and improve VoIP call quality.



Leased lines are the fastest business broadband service you can buy. If you can afford it you can get speeds in excess of 10 gigabits per second (Gbps) or 10,000 Mbps! Add to the high speed the dedicated bandwidth. This means that if you order 1 Gbps you will get 1Gbps of dedicated upload and download bandwidth for your business' sole use. 

Compare this with other shared broadband services which range from 10 Mbps to 300 Mbps download and 2Mbps to 30Mbps upload. You can see that a leased line has significantly higher speed capability than other broadband services.



All leased lines have guarantees. The guarantees are called service level agreements (SLA). The guarantees are in the contract small print and vary from provider to provider. If guarantees are not met the telecoms provider faces financial penalties, usually called service credits.

Leased line guarantees cover speed, uptime, packet-loss, round trip time, jitter. If you're not sure what these technical terms mean don't worry we will be going into these terms and why they are important in more detail.

Internet Access


Leased lines can be used by a business to connect a single office location to the internet. Usually this is when high-speed, reliable internet access is essential to the efficient running of the business.


Diagram: How A Leased Line Connects To The Internet



Multi-Site Networks


Leased lines are also used to connect multiple office locations in a network to the internet. This enables the multiple office locations to connect their local area networks and form a high-speed wide area network. There are different architectures that IT managers employ to acheive a wide area network complete with internet access. The two most popular architectures are:


Diagram: Single Site Internet Break Out



Diagram: Multi-Site Internet Break Out


TOP TIP: It is always best to design your leased line network with independent internet break out. The multi-site internet break out architecture above acheives this. The reason is because all sites have independant internet access, if there is a problem with the network at any site, the other offices will enjoy uninterrupted internet access.


Voice Over IP VoIP


A leased line is often used with a VoIP system. This is because the dedicated bandwidth over a leased line can be allocated to different services. Voice is one such service. By allocating voice bandwidth it is possible to guarantee call quality on the VoIP system. Leased lines also offer guarantees on jitter which improves call quality too. You can view a whole section below all about VoIP, jitter and leased lines which explains everything you need to know.

How fast are leased lines?


Leased lines offer the fastest fibre optic speed available. Most UK telecom providers offer up to 10Gbps.

There are three main components of speed in a leased line:

Bearer: The first element is the bearer or the size of the pipe. This is the size of the line that cannot be exceeded. It is the maximum capacity of the leased line. If a larger capacity is required, a new bearer may have to be provisioned, and it may need additional construction work.


Diagram: 100Mbps Leased Line Bearer

Circuit Speed: Circuit speed, also known as committed data rate (CDR), is the speed of the leased line that has been ordered and provisioned over the bearer. The leased line speed is more flexible than the bearer and may be quickly increased by the telecom provider.


Diagram: 50Mbps Leased Line Circuit

Internet Bandwidth: Internet bandwidth is provisioned over the leased line. It may be less than the circuit speed, but in most cases, it is the same as the circuit speed.


Diagram: 50Mbps Leased Line Internet Bandwidth

How do bearers, circuit speed and bandwidth affect the cost of a leased line?


Bearer Speed


In principle the faster the bearer speed the higher the price. To illustrate this we took NG7 2QJ as an example and compared 2 quotes from the same provider Virgin Media. The first quote was for 100Mbps leased line on a 100Mbps bearer, the second quote was for a 100Mbps leased line on a 1Gbps bearer. 


Graph: Leased Line Bearer Speed Impact On Costs

The 100Mbps line with a 100Mbps bearer cost £309.84 the 100Mbps line with a 1Gbps bearer cost £362.19. The monthly cost differential for a 1Gbps bearer was £52.35 or a price lift of 17%.


Circuit Speed


The faster the circuit speed the higher the price. To illustrate this we took NG7 2QJ as an example and compared 2 quotes from the same provider TalkTalk Business. The first quote was for 20Mbps leased line on a 100Mbps bearer, the second quote was for a 50Mbps leased line on a 100Mbps bearer.


Graph: Circuit Speed Impact On Leased Line Costs

The 20Mbps line with a 100Mbps bearer cost £228.47 the 50Mbps line with a 100Mbps bearer cost £270.94. The monthly cost differential between a 20Mbps circuit speed and a 50Mbps circuit speed is  £42.47 or a price lift of 18.5%.

ECCs stands for excess construction charges, so what do these charges have to do with leased lines?


Diagram: Illustrating Dig From Carrier To Customer



When leased lines are ordered, there is a requirement to build fibre to the location where the leased line will be terminated, usually the customer premises. ECCs occur when:


a. the carrier's fibre network has not yet been built out to the customer premises and the cost of building the fibre to the business is more than the carrier has provisioned, i.e. it's a long way.

b. the carrier's fibre network has not yet been built out to the customer premises, and the carrier does not deem that the customer location is a good fit commercially, i.e. it's remote.


Openreach describes why ECCs occur as follows:

ECCs are often raised where additional infrastructure is required to:

Provide new or extended service at a customer's site, or at another requested location where we would otherwise not choose to extend our network based on normal commercial criteria.
Situations involving extended reach including the provision of a new installation within your customer's site, as well as to those where existing capacity needs to be increased.

Some carriers tend to issue ECC charges more than other carriers.

BT, for example, has a standard "build" budget included in the installation charge for it's Ethernet Access Direct services. BT also has the largest network reach and the lowest likelihood of ECC charges. So which leased line providers are the best for avoiding ECC charges?


Graph: Excess Construction Charges By Carrier


BT on average has the lowest ECC charges, this is due to large network reach and ECCs budgeted into some leased line services. On average the ECC charge seen from BT is £3,336.

TalkTalk has on average ECC charges of £11,736 much higher than BT. Virgin have an average ECC charge of £20,032, Virgin are the worst carrier we work with for ECC charges.


You might be wondering if you need a leased line. The business drivers behind a leased line are fairly common and are explained below:

You Cannot Afford Any Downtime

If you have a large number of staff, or your business would stop without internet access it is likely the increased cost of a leased line is worth it. A leased line is more expensive than broadband or FTTC, but the bandwidth availability SLA and guaranteed fix times in the event of a failure are very valuable. Often the cost of an outage far outweigh the increased cost of a leased line and for this reason many businesses choose a leased line.

Large Data Transfer Requirements

If your business relies on transferring large amounts of data you may also require a leased line. Design agencies, architects, medical professionals and engineers often need to access and send large files. Additionally businesses using VoIP and cloud appliations also have large transfer requirements. If you transfer lots of data you may need the speed of a leased line.

You Are Dependent On VoIP

If you are dependent on VoIP, many businesses choose to install a leased line. The leased line service level agreements that cover jitter, packet loss and round trip time guarantee the bandwidth quality needed to run VoIP applications efficiently. Additionally, if you are dependant on VoIP, in the event of an outage, you will lose voice and data services. For these reasons the additional cost of a leased line is worth it due to the enhanced benefits associated with the leased line service level agreement.

You Need More Speed Than DSL, FTTC & EFM

Some businesses need more speed to operate efficiently. Sometimes the location of your business means that there is a long distance to the carrier network. Geographic factors can result in inferior DSL, FTTC and EFM performance and slow speed. You may have a remote location with limited broadband speed. You may have outgrown your existing broadband and need to upgrade to 100Mbps or 1Gbps fibre. A fibre leased line futureproofs your business and offers you as much speed as you can afford.

Leased Line Service Level Agreements

Leased line service level agreements or SLAs are the contractual guarantees that you receive when you purchase a leased line.

Leased line SLA guarantees cover availability, fix time, speed, performance factors such as packet loss, jitter, throughput and round-trip time. In the section below we cover the 4 largest UK leased line providers and compare the SLA agreements they offer to their customers.


Virgin Media Leased Line SLA


SLA ranges from Singlehomed (Ethernet Lite or Multi Tenant) 99.85%, Singlehomed (Ethernet or Leased Line) 99.90%, Resilient 100.00% - if Virgin fail to meet these availability guarantees they allow you to claim up to 10% of the monthly service charge.

Fix time:

If there’s a fault, Virgin aim to fix it within six hours (nine hours if it’s Ethernet Lite or Multi Tenant). If Virgin don't fix it you can claim as follows: 0-3 Hours past 10% of monthly rental; 3-10 Hours past 20% of monthly rental; >10 Hours past additional 5% monthly rental for every additional 1 hours.



BT Leased Line SLA


BT has a target availability of 100%. If this is not met you can claim as follows: Where the outage period is less than or equal to ten (10) hours, BT apply a reduction equivalent to one (1) day’s rental charge per hour of downtime for your service. The maximum reduction applied per quarter by BT is capped at ten (10) hours of outage.



BT has a latency guarantee which is an average round-trip transmission time of 20 milliseconds (20ms) or less between BT selected core PoPs in the BT Network.



TalkTalk Business Leased Line SLA


TalkTalk offer a 99.995% uptime guarantee.

Fix time:

TalkTalk offers an enhanced 5 hour fault fixing SLA for Ethernet Access Direct that's backed by service credits. TalkTalk do not publicise the service credits available in the event of an outage lasting more than 5 hours.


Colt Leased Line SLA


COLT have different availability SLAs as follows: HSS unprotected 99.70%; COLT HSS ETS protected 99.95%;  COLT HSS Path protected 99.97%; COLT HSS Active-Active pair 99.99%

If COLT fails to maintain this availability by 0.5% then 5% of the annual rental can be claimed. The ratios for 1% are 10% compensation, 1.5% is 15% compensation and the maximum level is 2% and 20% compensation. It's complicated!

Fix time:

COLT HSS protected on net is a 2 hour guarantee and off-net a 4 hour guarantee; COLT HSS unprotected on net is a 4 hour guarantee off-net is a 12 hour guarantee.

The compensation payable for a fix time outside of SLA is as follows: Hours past guaranteed fix 0-3 hours 5% of the monthly rental; 3-4 hours 10% of the monthly rental; 4-6 hours 15% of the monthly rental; 6-8 hours 20% of the monthly rental; greater than 8 hours 25% of the monthly rental.


Leased Line Lead Times

Leased line lead times range from 45 working days to over 120 working days. This means that if you order a leased line, you can expect it to take between two and six months for delivery. Different providers have different lead times and in the section below you can see the average lead time for each carrier.


Graph: Average Leased Line Lead Time By Carrier 

V.E.N have the lowest average lead time of 50 working days, TalkTalk are the next with 53 working days, BT deliver leased lines in an average of 58 days, Virgin Media's lead time is considerably longer at 95 working days, then SSE at 97 days and Vodafone have the worst leased line lead times at over 135 working days.

dedicated leased line
Dedicated Leased Line

Dedicated leased lines also known as 1:1 contended leased lines are not shared. All of the bandwidth is dedicated to your business meaning the speed is guaranteed for your sole use.

symmetric leased line
Symmetric Leased Line

Symmetric leased lines mean that the bandwidth speed is the same for upload and download. For example 50Mbps upload and 50Mbps download. 

leased line termination point
Leased Line Termination Point

The leased line termination point is the location to which the leased line will be delivered. For example Office suite 101, 3rd floor 181 Great Eastern Street, London EC2 5RT.

leased line bearer
Leased Line Bearer

The leased line bearer is the total capacity of the line you have ordered. For example you can order a 50Mbps leased line on a 100Mbps bearer.

leased line sla
Service Level Agreement

A service level agreement is the contractual guarantee a leased line provider offers for delivery, speed, availability and performance of the circuit you order.

leased line uptime
Leased Line Uptime

Uptime or availability is the measurement of the amount of time a leased line is in service and available to use. Most carriers offer uptime guarantees of between 100% and 99.9%

leased line packetloss
Leased Line Packetloss

Packet loss occurs when network routers or switches get overloaded. Packetloss causes data errors, jittery video and VoIP calls are dropped. Leased line carriers offer guarantees against packetloss in their SLA.

leased line jitter
Leased Line Jitter

Jitter in networking is the difference in delay of packets being sent and received. It's important as if packets are not received in the order they were sent then network problems are experienced. Leased line carriers offer guarantees against jitter in their SLA.

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