The UK’s voluntary code for mobile content could be replaced with more stringent rules following an upcoming review by telecoms regulator Ofcom. The Sunday Times reports that following complaints from charities, the Home Office has asked Ofcom to examine the scheme to prevent children from accessing unsuitable content such as pornography, gambling and other adult services on mobile handsets.

Currently, UK networks—including Orange, O2, Vodafone (NYSE: VOD) and T-Mobile—are signed up to a 2004 voluntary code in which they agreed to offer parents who bought 3G phones for their children filters to install that would block access to inappropriate content. A rating system for content was also ushered in, with all child-unfriendly content labelled with an “18”. The networks also agreed to work with the authorities on reporting any possible illegal content. But children’s charities believe that efforts by mobile operators to adhere to the code have been hit or miss, while at the same time owning and using a mobile phone among children is rapidly growing. Research firm mobileYouth says that one in three children under 10 own a mobile phone, while Ofcom’s own figures found that 32 percent of children aged 8-11 regularly use a mobile. The regulator’s report is due this summer.