which stations did it start with?
WEAF and WJZ
NBC
During a period of early broadcast business consolidation, radio manufacturer Radio Corporation of America (RCA) acquired New York City radio station WEAF from American Telephone & Telegraph (AT&T). Westinghouse, a shareholder in RCA, had a competing outlet in Newark pioneer station WJZ (no relation to the radio and television station in Baltimore currently using those call letters), which also served as the flagship for a loosely structured network. 
how much can you wager in final jeopardy 13, 420, and 911 who developed it? Merv Griffin how many levels does it have? Three is it a game that can be played on a given platform? It is a television game show featuring a quiz competition who hosts it? Alex Trebek what does the winner get? They are paid their winnings in cash which channel does broadcast it? NBC what it stands for? National Broadcasting Company when was it established? 1926
wiki:25654524
NBC [SEP] Earliest stations: WEAF and WJZ
During a period of early broadcast business consolidation, radio manufacturer Radio Corporation of America (RCA) acquired New York City radio station WEAF from American Telephone & Telegraph (AT&T). Westinghouse, a shareholder in RCA, had a competing outlet in Newark pioneer station WJZ (no relation to the radio and television station in Baltimore currently using those call letters), which also served as the flagship for a loosely structured network. This station was transferred from Westinghouse to RCA in 1923, and moved to New York City. WEAF acted as a laboratory for AT&T's manufacturing and supply outlet Western Electric, whose products included transmitters and antennas.