In the days when the US had net neutrality laws, CenturyLink would have been taken to the cleaners by the FCC for breaking customers' internet to look at paid advertising. These days the FCC is cheering as telcos come up with new ways to stick it to their customers who have to suffer because they are dealing with monopolies.
CenturyLink falsely claimed that it was required to do so by a Utah state law that says ISPs must notify customers "of the ability to block material harmful to minors". The new law requires only that ISPs notify customers of their filtering software options "in a conspicuous manner" - it does not say that the ISPs must disable internet access until consumers acknowledge the notification. The law even says that ISPs may make the notification "with a consumer's bill", which shouldn't disable anyone's internet access.
CenturyLink blocked the internet and injected a page using DNS spoofing which advertised a paid filtering software. "Clicking OK on the notice then restored my Internet... this is NOT okay!"
Users' internet access went out while users were in the middle of using their computer so if they were streaming on another device, it was not clear that the net had been switched off.
A CenturyLink spokesperson responded to a query from Utah-based news site KSL.com, saying: "As a result of the new law, all CenturyLink high-speed Internet customers in Utah must acknowledge a pop-up notice, which provides information about the availability of filtering software, to access the internet."
Bill sponsor Todd Weiler, a Republican state senator, confirmed on Twitter that the law "did not require that—and no other ISP has done that to comply with the law. They were only required to notify customers of options via email or with an invoice."