WOK was first licensed, as WCBZ, in April 1924 to the Coppotelli Brothers Music House in Chicago Heights, Illinois, for operation on 1210 kHz with a 50 watt transmitter.
[7] Following the establishment of the Federal Radio Commission (FRC), existing stations were initially issued a series of temporary authorizations starting on May 3, 1927.
They were formally combined into a single entity on November 1, 1927, when WOK was merged with WMBB, now operating under the control of American Bond & Mortgage, using a dual call sign of WMBB-WOK.
[9] The FRC conducted a review of existing stations, and notified them that if they wished to remain on the air they had to file a formal license application by January 15, 1928, as the first step in determining whether they met the new "public interest, convenience, or necessity" standard.
[10] The FRC's General Order 32, issued on May 25, 1928,[11] notified 164 stations, including WMBB-WOK, that they had been identified as questionable in meeting this new standard.