SMS (Short Message Service) gradually becomes the main service for cell phone users for its great charming. In addition, the development of mobile communications technology and service has created favorable condition for SMS. For example, MMS, multi-media messaging service, is a new type of message service on the basis of SMS. It allows transmission of multi-media messages between cell phone and computer, as well as between cell phones. Communication with SMS is quite convenient. You can write a message after carefully thinking what you want to say with many words without worrying about money. Actually, SMS enjoys the absolute majority utilization among mobile service. In China, the number of short message transmitted is 2,200 billion in 2003. People, however, feel angry and anxious sometimes while enjoying SMS. More and more rubbish short messages that contain such content as erotic, gambling, or advertising are sent to cell phone users, which seriously violated the user's privacy. Because the sender of these rubbish short messages do not take into account whether people need them or not, and do not get the permission from users to transmit these rubbish short messages to them. As we know, everyone has the right to communication freely with other people, and the right to refuse communication with people they don't like to. But these rights were not guaranteed in SMS. Users do not receive rubbish short messages on a voluntary basis. If you fell angry and disgusted with some rubbish message to your cell phone, and do not want to see it again, that means such message is in contradiction with your wish, and violates your privacy. MMS also promote the transmission of unhealthy information on the Internet from computer to cell phone, which must extend the scope and influence of rubbish short message. The rapid development of mobile communications may suffer a lot if there is no change in the way of transmitting SMS. More and more users of cell phone are disturbed by rubbish short messages, and their privacy is violated by mobile communications service, which is also not a benefit for the development of mobile communications service. ______has created a good condition for SMS.