Anyone using the O2 mobile network in the UK may find that some websites will no longer load when accessing them over a 3G connection. The reason is down to a new content filtering system O2 has rolled out this week blocking content not suitable for the under eighteens.The block has been implemented at the DNS level, but only applies to 3G connections. That means if you flick over to Wi-Fi no such content block is in place. The problem is the type of content being blocked, with Wired stating Google Translate and a sexual health charity being on the block list when they clearly shouldn’t be.O2 explain on its blog that it has implemented this filtering system to protect children who increasingly have their own smartphones capable of accessing the web. While commendable, the method of applying it to all phones without warning seems like a decision that was made without any forethought and has angered many subscribers.In order to have the block removed from your phone you have to prove your age. This can be done by visiting an O2 store with a passport proving your age, or by phoning a free automated service and using your credit card for verification. That second method costs a couple of dollars, but you get it back on your next phone bill.Because O2 hasn’t warned customers it was doing this, many have thought the age verification message that pops up for certain sites was spam. As you can imagine, the forums for the network have lit up with questions and complaints.Read more at WiredMatthew’s OpinionWhile offering an age verification system for your mobile network is a great idea, it’s one that should be an opt-in rather than opt-out service. Parents will want to activate it for their kid’s phones, but the majority of O2 users are going to be adults who don’t want this.It really doesn’t make much sense to apply it by default unless O2 was trying to save itself some marketing money for informing subscribers about the service. The alternative it has created is a lot of angry customers.I wouldn’t be surprised to see the new filter turned off before the week is out and an opt-in alternative given.