The variant sequence B - D + G = G, based on a G-major arpeggio in second inversion, was known as "the fourth chime". According to an NBC Interdepartment Correspondence memo, dated April 7, 1933 documents the conception and initial purpose of the fourth chime. The memo states "In anticipation of the Spring and Summer months, when many in key positions will not always be available at home telephones, the following Emergency Call System will go into effect on Monday morning, April 16." The memo goes on to say that whenever a fourth tone is heard on the network chimes rung at fifteen minute intervals, it will indicate that someone on an attached list is wanted. Upon hearing this fourth chime, all personnel on the list are instructed to call in to the PBX operator to ascertain whether or not the Emergency Call is for them. The chime would continue at fifteen minute intervals over stations WEAF and WJZ until the wanted person communicated with the PBX operator. The list contained the names of the following NBC executives:

John F. Royal, John W. Elwood, Frank Mason, J de Jara Almonte

The list also included names of personnel from Engineering, Press, Programming, Traffic, and Service departments.

The "fourth chime" was also used to notify affiliates and their employees of pending urgent programming. This variant saw such use during wartime (especially in the wake of the attack on Pearl Harbor) and other disasters, most notably the Hindenburg disaster in 1937. According to NBC historians, the last official use of the "fourth chime" was in 1945, shortly after the end of World War II. However, according to a handwritten note appended to an NBC internal memo originally dated 1964 on the history and usage of the standard chime, this chime variant was used one final time in 1985 to symbolize the merger with GE.