C August 24, 2004 Page 1 SMS Spam Control Nobuyuki Uchida QUALCOMM Incorporated Notice ©2004 QUALCOMM Incorporated. All rights reserved. QUALCOMM Incorporated grants a free, irrevocable license to 3GPP2 and its Organization Partners to incorporate text or other copyrightable material contained in the contribution and any modifications thereof in the creation of 3GPP2 publications; to copyright and sell in Organizational Partner’s name any Organizational Partner’s standards publication even though it may include portions of the contribution; and at the Organization Partner’s sole discretion to permit others to reproduce in whole or in part such contributions or the resulting Organizational Partner’s standards publication. Qualcomm Incorporated is also willing to grant licenses under such contributor copyrights to third parties on reasonable, non-discriminatory terms and conditions for purpose of practicing an Organizational Partner’s standard which incorporates this contribution. This document has been prepared by Qualcomm Incorporated to assist the development of specifications by 3GPP2. It is proposed to the Committee as a basis for discussion and is not to be construed as a binding proposal on Qualcomm Incorporated. Qualcomm Incorporated specifically reserves the right to amend or modify the material contained herein and nothing herein shall be construed as conferring or offering licenses or rights with respect to any intellectual property of Qualcomm Incorporated other than provided in the copyright statement above. Qualcomm Incorporated may hold one or more patents or copyrights that cover information contained in this contribution. A license will be made available to applicants under reasonable terms and conditions that are demonstrably free of any unfair discrimination. Qualcomm Incorporated reserves the right to use all material submitted in this contribution for its own purposes, including republication and distribution to others.

C August 24, 2004 Page 2 Why SPAM Control for SMS? SMS spam is any junk message delivered to a mobile phone as text messaging through the Short Message Service. Unsolicited text messages or SMS spam has become an industry wide problem. SMS spam control could be good topic we should think about in C.S0015.

C August 24, 2004 Page 3 Anti-Spam Techniques Black & White List –A spam black list is a list of IP addresses and domains of known spam servers. Black lists are used to block all that comes from certain servers on the Internet that have been identified as being used to send spam. –White lists are the opposite of blacklists. They list trusted addresses and domains that are always allowed to send , no matter what the content is. White lists are used to require that senders authenticate their identity prior to being delivered to the recipient. White lists will definitely allow coming from a trusted site to come through, but do not provide a solution for blocking spam. White lists require constant maintenance to be very effective. If not properly maintained, the risk of losing from legitimate sources is high. Bayesian Filtering –Bayesian algorithm is a popular technique used in fighting spam. Based on the ham (good ) and spam databases, Bayesian database is created. When a new message arrives, it’s broken down into words and the most relevant words are singled out. From these words, the Bayesian filter calculates the probability of the new messaging being spam or not. If the probability is higher than a threshold, then the message is classified as spam.

C August 24, 2004 Page 4 Objective and Requirements Objective –Reduce number of SMS spam delivered to the user »SMS filtering should be done in the network due to the limited resource in mobiles »Standardized feedback mechanisms from mobile so that the feedback can be used by the SMS filtering Requirements (examples) –Spam indicator along with source address and contents (MS -> MC) –Sapm threshold control (0 – 100%) (MS -> MC) –Spam header (MC -> MS) –Query status (MS MC)