A transparency campaign from


If you have any questions that are not answered below, please email blocked@openrightsgroup.org

If you are from an ISP, please read the ISP page.

I can see a website you say is blocked. Why?

The filters can be switched off, and are generally on by default on phones, and for Sky customers. You are probably not using filters on your network.

Why are all PlusNet results unblocked — I thought they are running filters?

Yes, they do run filters, but unfortunately they are broken for many of their customers, including us.

TalkTalk seem not to be filtering some obvious pornographic websites, why is this?

TalkTalk's filters on our line occassionally switch themselves off for a few hours. This seems to be a common problem. We try to detect it, but sometimes incorrect “unblocked” results will be recorded for a short period of time.

I cannot get results for [x] ISP or mobile service, why?

Sometimes our lines may go down, or other problems may arise. Mobile lines in particular can need rebooting, due to service coverage where our probes are.

Why are results for HTTPS sites less reliable than HTTP?

When a test is run against an HTTPS site that has been blocked by parental control systems, the probe attempts to set up a secure session with the requested server. The server that is used by an ISP to serve up the page that informs the user that the site has been blocked cannot provide a valid certificate for the address that has been requested, so the probe terminates the connection. The system records this as an SSL error rather than a definitive "blocked" result.

Questions about filtering

Who is affected by filters? Who exactly can’t see a website that this site says is blocked?

Network level filters
If your site is blocked by an ISP, it means that anyone in a household using network level filters, cannot visit your website. If they try they will get an error message. We have estimated figures for households that have filters activated below.

  • If your site is blocked by BT, it's blocked in approximately 550k households.
  • If your site is blocked by Sky, it's blocked in approximately 2 million households.
  • If your site is blocked by Talk Talk, it's blocked in approximately 450k households.
  • If your site is blocked by Virgin, it's blocked in approximately 650k households.

In total, that is around 3.5 million households, or approximately 7-12 million people, over half of whom will be adults.

Mobile filters

If your site is blocked by a mobile phone provider, it means that anyone using a phone with filters activated cannot visit your website. If they try they will get an error message. Mobile phone providers switch on filters by default and we don’t have figures for how many people have chosen to switch them off.

Is ORG against parents using filters?

ORG does not oppose the use of network level or mobile phone filters. However, we believe that activating them should be voluntary and that they shouldn’t be switched on by default. ISPs and mobile phone providers should also explain clearly that filters do not guarantee that a child won’t see harmful content and that useful content might also be blocked.

We also think that ISPs and mobile phone companies should raise awareness of filters among website owners so that they are aware that their websites might be blocked.

We would like more transparency about filters overall, including more information about how companies decide what should be blocked.

Do filters keep children safe online?

We are not aware of any research which demonstrates that filters are preventing children and young people from seeing harmful content. Researchers from the Oxford Internet Institute and Oxford University recently published a paper in the Journal of Pediatrics that found “convincing evidence that Internet filters were not effective at shielding early adolescents from aversive online experiences”.

Filters may stop a young child from accidentally stumbling upon pornography. However, it is largely accepted that a tech savvy teenager who wants to access pornography will find a way of doing so - whether through using Tor, VPNs, proxy sites or sharing through memory sticks.

Most filters do not block social media sites where porn is often shared, nor do they block self-generated images. They also don’t prevent other behaviour that makes children feel unsafe - for example bullying.

How can I protect my child online?

Parents need to talk to their children regularly about their internet use. For younger children, supervision might be needed while they are online.

Device level filters are another option and can help to initiate a conversation about harmful content as a parent has to activate them.

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