http://www.mirror.co.uk/news/uk-news/talktalk-to-offer-paren...
Mobile networks have always done silly blocking, and it takes a phone call to them to ask them to remove it. I assume it's more about them not wanting you to use more data than anything else.
It's a bit ridiculous (from the article) "meaning that any new TalkTalk users who require access to such content will first have to "opt-in" through a highly embarrassing call to customer services."
It's hardly "highly embarrassing" to ask them to remove a filter.
If they do go that route though, and as the article claims, ask you to opt-out once a year, then they'll simply lose customers to ISPs that don't hassle their customers.
I completely disagree. Many people would be very embarrassed phoning up to have an adult content filter removed. You can argue that they shouldn't be, but that's a different thing altogether.
[edit] Just to clarify, by "opt-in", I'm referring to opting in to receive everything. Perhaps "opt-out" in reference to opting out of the block, is clearer.