[CALAMOS INVESTMENTS(R) letterhead] March 15, 2007 Securities and Exchange Commission 100 F Street, NE Washington, DC 20549 FIDELITY BOND FILING Calamos Investment Trust - 1940 Act File No. 811-05443 Calamos Advisors Trust - 1940 Act File No. 811-09237 Calamos Convertible Opportunities and Income Fund - 1940 Act File No. 811-21080 Calamos Convertible and High Income Fund - 1940 Act File No. 811-21319 Calamos Strategic Total Return Fund - 1940 Act File No. 811-21484 Calamos Global Total Return Fund - 1940 Act File No. 811-21547 On behalf of Calamos Investment Trust, Calamos Advisors Trust, Calamos Convertible Opportunities and Income Fund, Calamos Convertible and High Income Fund, Calamos Strategic Total Return Fund and Calamos Global Total Return Fund (the "Trusts"), I am enclosing the following documents for filing under Rule 17g-1(g) of the Investment Company Act of 1940: 1. One copy of the Trusts' joint fidelity bond for the year ending January 31, 2008; 2. One copy of the resolutions adopted by the Trusts' board of trustees, including the trustees who are not "interested persons" of the Trusts approving the amount, type, form and coverage of the bond; 3. One copy of the fidelity bond insurance allocation agreement among the Trusts, Calamos Advisors LLC, Calamos Asset Management, Inc., Calamos Family Partners, Inc., Calamos Financial Services LLC, Calamos Holdings LLC, Calamos Partners LLC and the Calamos Profit Sharing 401(k) Plan. The premium on the bond has been paid for the period ending January 31, 2008. In addition, please note that the minimum amount of bond that each trust would have been required to provide, as set forth in Rule 17g-1(d), under a single insured bond is as follows: Calamos Investment Trust $2,500,000 Calamos Advisors Trust $ 350,000 Calamos Convertible Opportunities and Income Fund $1,250,000 Calamos Convertible and High Income Fund $1,250,000 Calamos Strategic Total Return Fund $2,100,000 Fidelity Bond Filing March 15, 2007 Page 2 Calamos Global Total Return Fund $ 600,000 Please acknowledge receipt of this filing by stamping the accompanying copy of this letter and returning it in the enclosed postage-paid, self-addressed enveloped. Sincerely, CALAMOS INVESTMENT TRUST, CALAMOS ADVISORS TRUST, CALAMOS CONVERTIBLE OPPORTUNITIES AND INCOME FUND, CALAMOS CONVERTIBLE AND HIGH INCOME FUND, CALAMOS STRATEGIC TOTAL RETURN FUND, CALAMOS GLOBAL TOTAL RETURN FUND /s/ James S. Hamman, Jr. ------------------------------------- James S. Hamman, Jr. Secretary