The ESRB and CTIA have unveiled details of a previously teased voluntary rating system for mobile apps, with support from six major mobile service and hardware providers but not mobile app leaders Apple and Google. The new system will let app developers fill out a questionnaire to instantly generate an age-appropriateness rating from 6+ to 18+. The process will be free of charge to developers. Ratings will take into account content such as violence, sex, language and substance use, as well as features such as the presence of user-generated content, location-sharing and third-party data sharing. The ESRB says it will "routinely test the most popular applications" to make sure the questionnaire-generated ratings are accurate, and respond to user complaints by promptly adjusting ratings found to be unreliable. AT&T, Microsoft, Sprint, T-Mobile USA, U.S. Cellular and Verizon Wireless will all offer support the new system on their various app stores and hardware, with each company announcing its own schedule for the roll out in the near future. The ESRB points out that the system will generate "consistent ratings across participating storefronts," but those ratings won't yet reach into two of the most popular mobile markets: Apple's 500,000+ app App Store and Google's 300,000+ app Android Marketplace. Apple's App Store features its own rating system that evaluates age appropriateness on a range of 4+ to 17+, while Google allows app developers to set their own optional ratings labels for submitted apps. "We've put a lot of effort into Android Market’s rating system, which now works well globally," Google spokesperson Christopher Katsaros told Bloomberg. "While we support other systems, we think it’s best for Android users and developers to stick with Android’s existing ratings." "We are proud to partner with the wireless industry in lending our expertise and credibility to the development of a rating system that effectively fulfills our mission of informing consumers while meeting the needs of this rapidly growing and evolving segment of the interactive market," ESRB president Patricia Vance said in a statement. "I applaud CTIA and ESRB on this consumer-friendly initiative," Arkansas senator Mark Pryor said in a statement. "It's a win-win when industry takes proactive, responsible steps to protect children from inappropriate content."