A transparency campaign from

Information for ISPs

What is this site?

This site tests for website blocks on ISP lines that we have access to. Currently, we have probes that are checking for blocks by filters at:

  • BT, testing the default “light” settings and the “strict” settings
  • Virgin
  • Sky
  • PlusNet
  • TalkTalk
  • Vodafone
  • EE
  • O2
  • Three

At times, our PlusNet filtering currently has not worked. You can read more about the technical difficulties PlusNet filters are experiencing here.

In each case, the line is configured to test for filtering and copyright blocks

You can view historic reports made to your ISP at https://www.blocked.org.uk/reported-sites 

You can also see how well your ISP is performing on our statistics page, which shows mistakes made and the time you take to respond.

Why are we receiving these reports? What do they mean?

You are receiving requests made by individuals on this website. 

The blocking reports themselves are generated by looking for your standard block page at website URLs, by our probe, on a line with your filtering enabled. The probe tests a list of over 23 million domains, by making a request for each on your network with filtering.

If the standard block page is recognised by our software, it marks the page as blocked by your filters. Our users may report this to you, once they have confirmed to us that they have checked the website.

We verify users email addresses as valid before we allow complaints to be submitted to you.

Individuals can either browse lists, search by keyword look at random blocks we have found, or test a specific website for a block.

What will we do with the blocking reports?

We aim to find out whether specific groups mare unfairly targeted by filters, how accurate filters really are, how many mistakes are made, and how responsive ISPs are at correcting mistakes.

We keep a record of reports made.

We also publish statistics about the scale of filtering.

How should we respond?

Please process the requests for unblocking against your criteria, and unblock any sites that appear to be incorrectly blocked. if you are not clear about how to do this, please ask your supervisor. As you should be able to see from the reports page, you are able to unblock websites that are incorrectly blocked.

Please do not ask our users for customer details or to switch filters off. They are mostly people who are not your customers and are not using filters, but rather want mistakes corrected. They may be personally affected, such as owners or maintainers of websites.

Where should our response emails go?

Please be careful to reply to our users to the email address it was sent from, which is an address @blocked.org.uk — this routes through our system and back to the person who sent the complaint. This lets us know that the complaint is dealt with and how.

What about court orders?

Some sites are blocked by court orders. We detect these separately, and record them as blocked by court order. Requests for unblocking of court order blocks cannot currently be made through this system. The list of URLs and domains we have detected as blocked by court order are here.

This is a work in progress. We hope to group these better for easier viewing and filter duplicate reports.


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Andrews and Arnold Ltd  :Bytemark Hosting  Top10VPN

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