CALAMOS Closed-End Funds: Calamos Convertible Opportunities and Income Fund (CHI), Calamos Convertible and High Income Fund (CHY) and Calamos Strategic Total Return Fund (CSQ) Announce Monthly Dividends NAPERVILLE, Ill., May 3 /PRNewswire-FirstCall/ -- CALAMOS INVESTMENTS announced today the declaration of monthly dividend distributions on each common share for its three closed-end mutual funds. Payable Record Ex-dividend Fund Dividend date date date CHI (inception 06/26/2002) Calamos Convertible Opportunities and Income Fund $0.1500 05/25/2005 05/13/2005 05/11/2005 CHY (inception 05/28/2003) Calamos Convertible and High Income Fund $0.1219 05/25/2005 05/13/2005 05/11/2005 CSQ (inception 03/26/2004) Calamos Strategic Total Return Fund $0.0875 05/25/2005 05/13/2005 05/11/2005 A dividend offers shareholders the opportunity to accumulate more shares in a Fund via the automatic dividend reinvestment plan. For example, if a Fund's shares are trading at a premium, dividends will be automatically reinvested through the plan at NAV or 95% of the market price, whichever is greater; if shares are trading at a discount, dividends will be reinvested at the market price. Thus, the plan offers current shareholders an efficient method of accumulating additional shares with a potential for cost savings. Please see the dividend reinvestment plan for more information. Additional information about the Funds, including a monthly commentary, portfolio holdings, and a description of the Funds' dividend reinvestment plan is posted at Calamos Investments' website, http://www.calamos.com/ . Important Notes About Performance and Risk: You can purchase or sell common shares daily. Like other investments, market price will fluctuate with the market. Upon sale, your shares may have a market price that is above or below net asset value and may be worth more or less than your original investment. Due to ongoing market volatility, performance is subject to substantial short-term fluctuations. Investments by a Fund in lower rated securities involve substantial risk of loss and present greater risks than investments in higher rated securities, including less liquidity and increased price sensitivity to changing interest rates and to a deteriorating economic environment. Shares of closed-end funds frequently trade at a market price that is below their net asset value. Fixed-income securities are subject to interest rate risk; as interest rates go up, the value of debt securities in a Fund's portfolio generally will decline. There are certain risks associated with an investment in a convertible bond, such as default risk - that the company issuing a convertible security may be unable to repay principal and interest - and interest rate risk - that the convertible may decrease in value if interest rates increase. About CALAMOS CALAMOS INVESTMENTS provides investment advisory services to institutions and individuals seeking superior risk-adjusted returns over the long term. With roots dating back to 1977, the company applies its proprietary investment process across an expanding range of investment strategies within the equity, global/international, balanced, high yield, convertible and alternative investment classes. For more information, visit http://www.calamos.com/ . DATASOURCE: CALAMOS INVESTMENTS CONTACT: Jeff Kelley of CALAMOS INVESTMENTS, +1-630-577-9687, Web site: http://www.calamos.com/

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