I'm a 48 yo father of two teen boys, both with iphones and we have a One plan with T-mobile. At home I use opendns.com to manage the internet and keep it as safe as possible for my boys, but I put web guard at teen setting on their phones to keep it safe. I observed them being a bit sketchy about their phones and was curious to see how good a job web guard was doing so I put it on teen setting on my phone and tested it. If you type "Pornhub.com" in your browser it does indeed block access. However, if you google pornhub, you can click the link and it connects with full content. The same is true for any websearch you might do on any topic that might bring up porn previews on your search...none of them were blocked. I tested both the native iphone safari browser and the firefox browser for iphone. Meanwhile, I was out doing some shopping for dinner and I love the website seriouseats.com for recipes so I typed that in....blocked. Huh? A food site it blocked from a teen setting?? So, thinking I had discovered a loophole for web guard I googled it and clicked the link....also blocked.
Summary: Web guard is excellent at blocking pictures and videos of food, but lousy at porn. I'm emailing them to let them know but it's something parents may want to be aware of as well.