This greeting is much newer than most people think. The use of hello as a greeting is only as old as the telephone. The first recorded use is from 1883.
It does, however, have earlier origins in other senses. It is a variant of hallo, which dates to 1840 and is a cry of surprise. That in turn is related to halloo, a cry to urge on hunting dogs. Halloo dates to about 1700, but a variant, aloo, appears in Shakespeare's King Lear a century earlier than that.
And there is an even earlier variant, hollo, which dates to at least 1588 when Shakespeare used it in Titus Andronicus. There are also cognates in other Germanic languages.
Hello was not a shoo-in for the telephone greeting either. It competed with several other options, including Alexander Graham Bell's suggestion of Ahoy, but pulled into an early lead and by the end of the 1880s was firmly ensconced.
Hello 也并非打电话时的唯一问候用语，同时还有其它的几种说法，包括亚历山大格拉赫姆贝尔(Alexander Graham Bell)所提议的“喂” (Ahoy)。但是Hello被使用得较多，到了十九世纪八十年代末期，其用法得以固定。