Siebel Systems to Present at UBS Software & IT Services Conference

Business Wire, May 23, 2005

SAN MATEO, Calif. -- Siebel Systems, Inc. (Nasdaq:SEBL), the leading provider of customer-facing solutions, today announced that Keith Raffel, Group Vice President, Products, OnDemand and SMB, will participate in a panel discussion titled "The Evolution of CRM: Which Model will Prevail?" at 8:50 a.m. Eastern Time/ 5:50 a.m. Pacific Time, on Tuesday, May 24, 2005. The UBS Software & IT Services Conference is taking place in New York, NY.

Live and archived broadcasts can be accessed at www.siebel.com/investor.> About Siebel Systems

Siebel Systems is the world's leading provider of customer-facing solutions that deliver demonstrable business results and long-term competitive advantage. Siebel's multichannel offerings allow organizations to intelligently manage and coordinate all customer interactions across the Web, contact center, field sales/service force, branch/retail network, and indirect and partner distribution channels. Siebel solutions draw upon the company's best-in-class capabilities in customer relationship management (CRM), business intelligence, and customer data integration and can be deployed as licensed software or as a hosted service. Siebel solutions are tailored to the unique needs of 23 industries and incorporate industry-specific business processes, best practices, and business insight. They are the product of more than $2 billion in R&D investments and reflect over 11 years of experience with more than 4,000 organizations. Together with its extensive global network of alliance partners, Siebel provides the people, process, and technology expertise critical in driving business value from the deployment of customer-facing solutions. Over 3 million users worldwide in organizations of all sizes depend on Siebel solutions to deliver dramatic improvements in how they identify, acquire, retain, and serve customers. For more information, visit www.siebel.com.

For more information on Siebel Systems solutions and services, please visit our Web site: CRM - http://www.siebel.com/crm; OnDemand Solutions - http://www.crmondemand.com; Industry CRM - http://www.siebel.com/industry-crm; Call Center & Service - http://www.siebel.com/call-center; Sales Force Automation - http://www.siebel.com/sales-force-automation; Marketing Automation - http://www.siebel.com/marketing-automation; Business Intelligence - http://www.siebel.com/business-intelligence; Integration Solutions - http://www.siebel.com/integration-solutions; CRM Services - http://www.siebel.com/crm-services

Except for the historical information contained herein, this press release contains forward-looking statements that involve risk or uncertainties. Future operating results of Siebel Systems may differ from the results discussed or forecasted in the forward-looking statements due to factors that include, but are not limited to, risks associated with customer relations, such as the availability of Siebel Systems' products and services, customer implementation of products and services, relationships with customers, third-party vendors and systems integrators, concentration of revenues in a relatively small number of customers, existence of errors or defects in products, ability to successfully manage growth, significant current and expected additional competition and the need to continue to expand product distribution and services offerings. Further information on potential factors that could affect the financial results of Siebel Systems are included in Siebel Systems' Annual Report on Form 10-K, Quarterly Reports on Form 10-Q and its other filings with the Securities and Exchange Commission, which are available at www.sec.gov. Siebel Systems assumes no obligation to update the information in this press release.

Siebel is a trademark of Siebel Systems, Inc. and may be registered in certain jurisdictions. All other product and company names mentioned are the property of their respective owners and are mentioned for identification purposes only.