When telephones were invented, along with them came a new dilemma. What to say when answering?
Although the word ‘hello’ did exist in English before the invention of telephones – originally from French “ho, là” (“Oh! Over there!”), mostly used as a term of surprise rather than greeting, and often spelled ‘holla’ or ‘hullo’ – prior to that time most greetings referenced the time of day: ‘Good morning,’ ‘Good evening’ and so on.
Alexander Graham Bell, the inventor of the telephone, initially proposed ‘ahoy ahoy’ or ‘ahoy hoy’, derived from nautical terminology, as an effective way to start a phone conversation. But ‘hello’ caught on, and with the exception of Mr Burns on The Simpsons, nobody uses ‘ahoy hoy’ these days. And as telephone use became ever-more common, ‘hello’ came to be firmly embedded as the standard casual greeting in the English language.
Meanwhile, of course, the phone was having similar impacts in other linguistic environments. Many languages ended up adopting a variant of ‘hello’ (like ‘allô’ in French and ‘alo’ in Turkish) but others use completely different words. In Korean, for example, people say 여보세요 (Yeoboseyo), which derives from ‘여기’ (yeogi) meaning ‘here,’ ‘보다’ (boda) which comes from the verb meaning ‘to look’ or ‘to see,’ and ‘세요’ (seyo), a polite ending used in formal speech, and means essentially ‘Are you there?’, making it a greeting that should only really be used when answering the telephone.