How did the phrase “Roger that” originate?
In the 1940s, the American military and British RAF used a spelling alphabet different from the current well-known Alfa, Bravo, Charlie.
The letter “R” was used as an abbreviation for “received” back in the times when messages were send via telegraphy (in Morse code), and the practice of confirming that a transmission was received by sending an “R” back was extended to spoken radio communication at the advent of two-way radio during World War II.
The phonetic alphabet used by the British and American military during the World War II was: Able, Baker, Charlie, Dog, Easy, Fox, George, How, Item, Jig, King, Love, Mike, Nan, Oboe, Peter, Queen, Roger, Sugar, Tare, Uncle, Victor, William, X-ray, Yoke, Zebra
When a soldier or a radio operator said “Roger” after receiving a transmission, he was simply saying “R” for “received”.
The alphabet has changed since then, but the practice of replying to a message by saying “Roger” stuck.