What is this Telephone numbers used to begin with two letters, which were an abbreviation for a word. For example, there was a Glenn Miller song called PEnnsylvania 6-5000, and Liz Taylor made a movie called BUtterfield-8. I'm just barely old enough to remember that my phone number at home when I was 5 or so started with SYcamore 4, or SY4. These were telephone exchanges, and had exchange names ...