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What is broadband traffic management and traffic throttling?

There are now tens of millions of broadband connections across the UK, and demand is showing no sign of slowing down. 

That puts ISPs under a lot of pressure as they have to maintain an acceptable level of service for millions of home and business users all over the country.

And if things go wrong social media offers an instant and very public channel for complaining, which can quickly have an impact on their reputation.

One way ISPs can manage demand and keep things flowing smoothly for everyone is traffic management, also known as broadband throttling. But this can lead to unexpected issues for broadband subscribers who aren’t aware of such policies and how they can impact their experience.

In this guide, we'll explain what traffic management is and tell you which providers use it.

Traffic management: the key points

  • Traffic management can be used to restrict internet speeds.
  • It most commonly affects file sharing.
  • Some providers are truly unlimited and do not use traffic management.

What is broadband throttling, and how does it work?

Providers can deliberately slow down internet access, either for all communications or specific types of traffic. There are various terms for this, including throttling and traffic shaping, but all fall under the umbrella of traffic management to describe how and why an ISP controls the enormous amount of data passing through its network

As data is transferred, ISPs can slow it down or prioritise certain types of traffic. The connection still works, but end users will experience throttling as a reduction in performance. You might encounter buffering on videos, find that web pages have a more noticeable loading time, and downloads and uploads take longer.

Traffic management is not only used for fixed-line home broadband but it's also implemented on mobile broadband, where bandwidth can be even more limited.

Why do broadband providers use traffic shaping?

Although ‘broadband’ implies a very wide road, the virtual highways only have so much room to carry information. An overloaded network can slow things down for everyone.

We're now using our connections for much more demanding behaviour such as streaming video, internet telephone calls, and large file downloads. As a result, networks have had to deal with a lot more data.

How much more? In 2002, fixed-line internet traffic was about 356 petabytes per month. By 2012, this had increased to an incredible 31,338 petabytes. That's the equivalent of 31,338,000 1TB computer hard drives full of selfies, Tweets, and cat videos being sent over the internet every month. 

To handle this without everything grinding to a halt, traffic management may be implemented to restrict or prioritise certain types of traffic, sometimes even limiting the speed of all connections. 

The how and when of traffic shaping policy differs between providers as each has its own definition of peak time and approach to types of traffic.

Typically, it will be in action from around 8 am to 11 pm and mainly affect file sharing, because that can result in a small number of users consuming a disproportionate share of the bandwidth.

However, other activities such as voice calling and online gaming may be prioritised to improve performance.

So at busy peak times when everyone is using the internet at work or home browsing their favourite sites and streaming a boxset off Netflix, ISPs will slow some traffic to ensure a satisfactory service for everyone else. BitTorrent downloads could get slower, but you’ll still be able to stream Breaking Bad in HD.

  • My broadband is slow: am I being throttled?

    It’s a possibility. First, make sure you’ve not exceeded any data usage limits for your broadband package. Use your provider’s online management tools or check your email to see if you’ve been notified about a violation of a usage limit. Obviously, this does not apply if you’re on an unlimited package (unless your ISP has a sneaky fair use cap, which is increasingly rare these days).

    Next, check the ISP’s traffic management policy to find out when it is active and what kind of things are affected.

    If you’re outside peak hours or not doing anything which should fall under the policy, then the issue lies elsewhere so it might be a question for tech support. For more information, we have guides to troubleshooting home and mobile broadband and contact details for home broadband and mobile broadband

Which broadband ISPs use traffic management?

Policies vary between providers so you will need to do some research if traffic management is likely to get in the way. You should be able to find the information on each ISPs site, and as most are signed up to the BSG code of conduct, the traffic management policy should be clearly defined.

If you're having difficulty tracking down the terms on a provider's site, it may be easier to find it via a Google search.

Remember that some ISPs have a fair usage policy which includes a cap on data usage each month in addition to traffic management. Exceeding their monthly download limit can result in your connection being throttled until the next billing period or a charge for additional data.

However, there are an increasing number of ISPs that offer totally unlimited broadband.

Home broadband traffic management policies

Every ISP approaches this differently, but here’s some information on how the big players handle traffic management.

BT Broadband

  • Affected packages: BT TV
  • Peak times: n/a

BT only uses traffic management to prioritise TV services for on-demand viewing. Extra bandwidth is utilised for this, so it does not impact other users.

Sky Broadband

  • Affected packages: Sky Connect
  • Peak times: 16:00 - 23:00 weekdays, all day weekends

Only Sky Connect packages have traffic management. It is used to prioritise browsing, email, media streaming, VOIP, and gaming. At peak times peer-to-peer file sharing and newsgroups are slowed, and heavy users may find their connection reduced by 90% between 17:00 and 00:00.

Other Sky packages - including Sky Unlimited and Sky Superfast -  have no traffic management or data usage limit.

TalkTalk Broadband

TalkTalk has almost no traffic management at any time. Like BT, the exception is for those on a TV package, where TV streamed to the YouView box is prioritised over other traffic.

Virgin Media

  • Affected packages: Fibre 20 (30GB cap)
  • Peak times: n/a

Virgin only applies traffic management to the old Fibre 20 service, which has a 30GB usage cap, and only if the usage cap is exceeded and Virgin is unable to apply its unlimited top-up fee. In that situation, download speed is slowed until you pay for the top-up, or until the next billing period. 

All other Virgin packages are truly unlimited and do not have traffic management.

Mobile broadband traffic management policies


  • Peak times: 08:00 - 02:00

EE restricts peer-to-peer traffic to a maximum 50Kb at peak and 1800Kb at other times. No other type of traffic is affected.


  • Peak times: n/a

O2 does not implement traffic management for mobile broadband.


  • Peak times: 15:00 - 00:00

Peer to peer slowed at peak. Streaming video is ‘optimised’ for performance, which may equate to lower quality, but Three does not provide details.


  • Peak times: n/a

Vodafone does not implement traffic management for mobile broadband. 

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