The rather detailed response provides a good explanation on the technology associated with network based web filtering service - how illegal traffic is blocked (based on IWF lists - here) and how sites are categorized using a pre-populated database and real-time content analysis.
"The Bluecoat filter you refer to classifies every internet site into one or more of over 70 categories. In order to apply the adult bar to protect our younger customers, Vodafone take these 70+ categories and rates them as either Adult of Universal. As the internet is growing at an ever increasing rate, so there are a percentage of sites not yet classified by Bluecoat as they are too new. To be on the safe side, when a user requests a site that is not classified, the Bluecoat system pulls the page requested and checks to see if there is any obvious content that would make it necessary to classify it. If it does appear adult, then the warning page is displayed. If not, it is served to the customer in the normal way. In order that we preserve customer service in terms of performance, but do not compromise safety, this is all done simultaneously. Vodafone do not retain any of this information. The site will be dynamically rated on each visit. If the site is a more popular one, it is added to the database and the checking process would stop occurring If a customer is over 18 then they can access any internet site they wish with the exception of sites dealing with child abuse images as classified by the IWF. If a customer is under 18 then where content is regarded as unsuitable we serve a warning page.Bluecoat does not constitute ‘spyware’. It is a network operation applied to every internet request and we are required to do this in order to meet our regulatory and industry obligations. This is not a question of intercepting customer communications but the safety of our younger customers in a dynamic environment. Other network operators use the same or similar systems"
See "Vodastalk; Vodafone and Bluecoat Stalking Subscribers" - here.
- UK Government Pushes ISPs (Again) to Provide Better Parental Control - here
- UK: Public Pressure on ISPs to Enforce Parental Control (Killing a VAS?) - here
- Vodafone Turkey Uses Optenet and Allot for Web Filtering - here
- TalkTalk [UK] Launches Free, Opt-in, Parental Control/Malware Detection - here