China issued 3G (third generation) mobile network licenses to its three mobile carriers early this year, and the number of 3G users in China has slowly climbed since then. This year the country has also closed thousands of Web sites and arrested dozens in a campaign against online pornography that is increasingly shifting focus to mobile Web sites.

But Chinese owners of mobile porn Web sites have been able to evade authorities through technical tactics such as frequently switching domain names and IP (Internet Protocol) addresses. Counter-tactics being used by authorities include a blacklist to prevent pornographic Web sites from reappearing online and the design of content-filtering technology to help network operators themselves block obscene content, said officials.