According to 4chan's Twitter account and status update blog, they have been "explicitly blocked" by the Verizon wireless network.

If you're unfamiliar with 4chan and why an ISP/wireless company would block it, read more about it on Wikipedia. The high-traffic image board of mostly anonymous users was created by Christopher Poole in 2003 and has been the subject of a fair amount of negative media and legal attention over the past six years. But why would Verizon choose to block the site now? Does this put Verizon on par with foreign ISPs that block torrent sites and social networks? Or is there more to the story?

Poole wrote this afternoon, "Over the past 72 hours, we've been receiving reports from Verizon Wireless customers having difficulty accessing the image boards. After investigating, we found that Verizon is dropping traffic... only on port 80 (HTTP). No other subdomain/IP/port is affected, which leads us to believe this block is intentional."

However, a couple hours ago, Poole posted, "After an hour and a half on the phone, we've received confirmation from Verizon's Network Repair Bureau (NRB) that we are 'explicitly blocked.'"

In the past, we've held a generally negative view of ISP censorship and traffic shaping, regardless of site content. It'll be interesting to see how this battle shapes up, as Poole is calling for 4chan users to file complaints with Verizon's Network Repair Bureau.

We are contacting Poole and Verizon to figure out specifically why the site is being blocked and will update this post as more information becomes available.

While we've personally confirmed that the image boards are not accessible from the Verizon wireless network, we're not certain that Verizon as an ISP is blocking the site or whether they plan to in the near future. Again, a move of this magnitude would have to have some pretty compelling justifications, and we can't wait to find out Verizon's reasons.

This incident calls to mind AT&T's temporary blocking of the site in July 2009. Eventually, AT&T said the block was due to a DDoS originating from 4chan IP addresses, to which Poole responded, "We're glad to see this short-lived debacle has prompted renewed interest and debate over net neutrality and Internet censorship - two very important issues that don't get nearly enough attention - so perhaps this was all just a blessing in disguise."

UPDATE: A Verizon NRB rep said their center has been deluged with phone calls but was unable to relate the specific reason the site has been blocked. We are continuing to call other Verizon numbers at this time, but we've been alerted that Verizon has not yet set up any process for dealing with media calls on this issue as no other media outlets have yet contacted them.

UPDATE: Multiple Verizon FIOS/DSL customers have let us know that the boards are still accessible from other devices not on the Verizon wireless network. However, we're confused as to why Verizon wireless would block a website and still allow access on other parts of its network.

UPDATE: Poole, a.k.a. Moot, responded to our email this morning, confirming that only Verizon Wireless customers were effected by the block - not FIOS/DSL customers. As for the reason for the block, he wrote, "None of the techs could give us a definitive answer. It took them hours to even figure out/acknowledge the block was occurring on their end."

A major wireless and Internet provider can't tell a website owner why his site is blocked? It's interesting, but the day is young. We hope to receive word from Verizon soon. A Verizon PR exec has said he is looking into the matter, but hasn't yet been able to give us any definitive answer.