The red telephone box was the result of a competition in 1924 to design a kiosk that would be acceptable to the London Metropolitan Boroughs which had hitherto resisted the Post Office's effort to erect K1 kiosks on their streets.

Answer this question based on the passage: when was the first red telephone box invented? Let's have some stream of consciousness first.
To answer the above question, the relevant sentence is: The red telephone box was the result of a competition in 1924 to design a kiosk that would be acceptable to the London Metropolitan Boroughs which had hitherto resisted the Post Office's effort to erect K1 kiosks on their streets. So, the answer is 1924.