A Dictaphone is an office machine you speak into. You record a letter, a note, or a report; later someone (often a typist, or you yourself) plays it back and writes it down. It is not a telephone: nobody is listening on the other end while you talk. The word began in the early 1900s as a brand name, built from dictate (speak so someone can write it) and -phone (a machine for sound). People then used it for that kind of machine in general, the way a brand can become the everyday name. You will meet it mostly in older office stories. Today a phone voice-memo or a small digital recorder does the same job. In careful writing, dictation machine is the plainer term.