Guide to ISP web filters and web blocking
For several years many of the UK's broadband service providers have been filtering and blocking web sites, limiting access to content that’s deemed sexually explicit, violent or dangerous.
This filtering stems from the government's 2010 manifesto, in which it stated an intention to protect children from harmful web sites.
Since 2013 all new customers to the four biggest ISPs - along with many of the smaller providers - were automatically opted in to web filtering. In 2014 this was extended to all existing subscribers too. If you haven't previously chosen to opt out of the filtering, it's likely your connection will be affected.
But what are these filters, what sites do they block and how can you control them?
What are ISP web filters?
The web filters introduced by ISPs use network level filtering of broadband connections to block access to adult and illegal content. The filters use blacklists of restricted sites and automatically block pages by examining keywords to guess whether a site should be prohibited.
Because this blocking is occurring at the network level it does not rely on software or hardware in your home and is applied to the entire connection, so filtering works on any connected device. The advantage for parents is that they don’t need to worry about configuring settings on every bit of hardware that has a web browser. Whether your kids are using a smartphone, tablet, games console or computer, the filtering can prevent them accessing unsuitable sites.
What sites are blocked by web filters?
Typically the filters will block sites about drugs, alcohol, tobacco, pornography, nudity, terrorism, suicide and self harm, hate speech, violence and gore, gambling, social networking, file sharing, online gaming, anonymising services, dating, hacking and bullying. Sites involved in malware distribution and phishing will also be filtered.
However, there is little consistency between providers and each ISP has its own way of categorising and filtering content. You can find a detailed breakdown of blocked content for the four biggest ISPs on the Wikipedia page for web blocking, and the Open Rights Group maintains the Blocked.org.uk web tool which can be used to check if a site is filtered by ISPs.
In addition to the above content, ISPs also block child abuse and piracy sites. The Internet Watch Foundation (IWF) monitors for child abuse online and maintains a block list, while file sharing sites such as The Pirate Bay are blocked by court orders, along with proxy services designed to bypass the filters. Unlike other categories these illegal sites cannot be accessed by opting out of the filter.
Web filter controversies
The use of web filters in the UK has been extremely controversial. There is no independent oversight of the ban lists, and nothing preventing the government from extending the filter beyond its original mission to clamp down on political dissent. And while the filters can be disabled right now, there’s no rule that says this capability can't be withdrawn in the future.
Beyond the worrying Big Brother overtones of such filtering, one of the biggest issues is overblocking - the unintentional restriction of legitimate content.
The categories are broad so perfectly innocent sites can get caught in the net. This can easily affect gaming and dating services, but is especially problematic for sites dealing with issues such as eating disorders, sexual health and education and domestic violence. The most vulnerable people in society can be left without access to important help and guidance.
If you choose to enable your ISP web filter it’s important to consider the impact on your family. Take the time to examine the options and, when possible, configure the filters to block unsuitable content without being overly strict. Even then, the filters are far from perfect so you may have to frequently login to the filter controls and manually block or unblock sites.
How to control your ISP web filters
The web filters operate on an opt-out basis, which means they are automatically enabled for broadband subscribers until manually disabled. So if you’d rather not use them at all you can simply login to your ISP account controls and cancel all filtering.
But in addition to a straightforward on/off switch, ISPs offer a variety of options to customise the filters. This allows finer control over the settings to prevent overzealous blocking while still protecting your family from unsuitable sites.
The settings vary with each ISP, but most offer some or all of the following options:
Enable blocking only at specific times, helpful if you want to disable the filter for the grown-ups in the house when the kids aren’t using the internet. Some ISPs use a 'watershed' setting for either disabling the filter or switching to adult only filters at certain times.
A homework mode implements stricter rules to prevent kids wasting time on social networking or games when they should be studying.
All web filters allow you to choose the level of filtering. With some providers you’re simply presented with a list of categories which can be enabled/disabled individually, while others offer pre-configured age rating groups or filter levels.
Blacklisting and whitelisting
If there’s a site that’s fallen outside the filter, or you wish to exclude a specific site from filtering, you can manually specify a URL to blacklist or whitelist it.
Controlling the filters for BT, Sky, TalkTalk and Virgin Media broadband
Each ISP has its own name for the filter, and the choice of settings varies too. Below is a brief guide to the web filters for some of the most popular ISPs; if yours is not listed check the online help pages or contact support for more information.
At this time not all ISPs offer filtering. While the government put pressure on providers to implement this system, it is not a legal requirement and many smaller companies are yet to comply.
BT Parental Controls
To access BT Parental Controls you will need your BT ID and password. Login in to My BT and navigate to the Parental Controls panel.
You can choose from pre-set filter levels of Light, Moderate and Strict, or customise the blocked categories. BT Parental Controls also offer a timer, homework settings and black/whitelisting.
When faced with a blocked site, the BT Parental Controls give anyone with access to the BT account the option of overriding the filter for one hour, or permanently whitelisting the site.
Sky Broadband Shield
To configure Sky Broadband Shield visit https://broadbandshield.sky.co.uk and login with your Sky ID account.
Sky uses age ratings to control the filter level. You can choose from PG, 13 and 18 filter levels, however unlike others there is no custom filter settings. 18 is recommended for adults as it permits all content except for phishing and malware pages which pose a security threat.
Sky also offers a watershed option which automatically switches to the 18 filter at set times, and you can manually block or allow specific sites.
TalkTalk’s HomeSafe filter is accessed via your TalkTalk account page.
TalkTalk’s “Kid Safe” filter does not use pre-set groups like Sky or BT, instead you’re given the option to select from nine specific categories to block. It has a “homework time” option too, which blocks gaming and social media during the chosen time period.
You can also blacklist and whitelist particular web sites if they are not covered by the filter or you wish for them to be excluded from blocking.
Virgin Media Web Safe
Login to your My Virgin Media account and click My Apps then Web Safe.
Virgin offers two different types of filter: Virus Safe and Child Safe. The Child Safe filter offers the ability to block groups of sites by category, configure blocking for specific web sites and has a timer to disable and enable the filter automatically.
Virus Safe is designed to protect against malicious sites. This can provide a useful extra layer of security, but it is still important to have anti-virus software.
Web filtering on mobile broadband and mobile phones
It’s not just fixed line home broadband that uses web site filtering, mobile networks also censor content online. In fact mobile networks were way ahead of the game and began web blocking in 2004, following Ofcom’s publication of the UK code of practice for the self-regulation of new forms of content on mobiles.
The mobile networks do not utilise the same blocks as home providers. Mobile operators use guidelines developed by the BBFC which classifies sites on a similar basis to an 18-rated film - filtering out sexually explicit, gory, violent, and drug related content.
However, overblocking is reported to be a significant issue on mobile devices with many sites falling foul of the filter. Compounding this is the lack of customisation on some mobile network filters. The mobile internet blocks do not always offer the same level of control as home broadband - they may be either on or off, with no way to tailor the filters.
Disabling blocking can be more involved too. In order to cancel the filter you will need to verify your age, which involves either going into a high street store with ID, or providing credit (not debit) card details on a mobile app or over the phone.
More information about controlling the filters can be found on these network support pages: