Hello Girls
Hello Girls was the colloquial name for American bilingual female switchboard operators in World War I, formally known as the Signal Corps Female Telephone Operators Unit. During World War I, these switchboard operators were sworn into the U.S. Army Signal Corps.
This corps were formed in 1917 from a call by General John J. Pershing to improve communications on the Western front. Applicants had to be bilingual in English and French. Over 7,000 women applied, but only 450 were accepted. Many were former switchboard operators or employees at telecommunications companies. They completed their Signal Corps training at Camp Franklin, now a part of Fort George G. Meade in Maryland.
History
Much earlier (than WW1) published references to "Hello Girls" exist. The term was first coined for the female telephone switchboard operators in the US. The earliest reference is in Mark Twain's A Connecticut Yankee in King Arthur's Court written in 1889. Although the term may have been applied to the signalling corps, it did not originate there but was rather the common term used for the ladies who would say hello when you rang the switch as opposed to direct calling.