65 ILCS 5/11-23-15
Revenue bonds issued on or after March 1, 1965 under Sections 11-23-13 and 11-23-14 may be redeemed by the municipality issuing them on such terms, at such time, upon such notice and with or without premium all as may be provided in the ordinance authorizing them.
Revenue bonds issued prior to March 1, 1965 under Sections 11-23-13 and 11-23-14 may be redeemed on any interest-paying date, by proceeding as follows: (1) a written notice shall be mailed to the holder of such bond 30 days prior to an interest-paying date, notifying the holder that the bond will be redeemed on the next interest-paying date; or (2) if the holder of such bond is unknown, then a notice describing the bond to be redeemed and the date of its redemption shall be published 30 days prior to an interest-paying date in one or more newspapers published in the city, or, if no newspaper is published therein, then in one or more newspapers having a general circulation within the city. When notice has been mailed to the holder of such bond, or when notice has been published in a newspaper in case the holder of the bond is unknown, the bond shall cease bearing interest from and after the next interest-paying date.
65 ILCS 5/11-23-15