It is generally agreed that the first paid radio commercial was developed by 
WEAF in New York by AT&T in August of 1922. The book titled "The WEAF
Experiment" by an AT&T employee describes the concept of "toll broadcasting"
to advertisers, in which businesses would underwrite or finance a broadcast, in
exchange for being mentioned on the radio. The first sponsor, or commercial –
according to AT&T – came from the Queensboro Reality Corporation of New
York, advertising an apartment complex. The set of five programs over five
days starting 8/28/22 cost $50, plus the long distance access fee.