William Grimes, writing for the New York Times in 1992:
Over at the laboratories of Edison’s rival, Bell was insisting on “Ahoy!” as the correct way to answer the telephone. It was trounced by “hello,” which became the standard as the first telephone exchanges, equipped by Edison, were set up across the United States and operating manuals adopted the word. The first public exchange, opened in New Haven on Jan. 28, 1878, wavered between “hello” and the fusty “What is wanted?” in its manual. By 1880, “hello” had won out.
I can’t see why “What is wanted?” didn’t win out. It’s just so…so…genial.