In the 1930′s and 1940′s, as telephone numbers began to increase in digits, “telephone exchanges” were introduced to make it all a bit easier to remember. The first two digits of a phone number were referred by a word incorporating their related letters – for example, PEnnsylvania 6-5000 would mean to dial PE6-5000, or 736-5000. You can still find remnants of this on older establishments around the city, such as the Lumber Boys store on Second Ave:
Right above the door is this old wood-cut phone number:
I’m curious what word the MU used to stand for, as I assume it was a pretty big Manhattan exchange. UPDATE! Commenters have pointed out that that MU stood for MUrray Hill. Nice.
Interestingly enough, PEnnsylvania6-5000 is allegedly the oldest phone number in continuous use in New York City, dating back to 1919. The number calls the Hotel Pennsylvania, near Madison Square Garden, and was immortalized in the hit song PEnnsylvania6-5000 by Glen Miller. Despite numerous ownership changes, the number has stuck with the hotel. Call it and you’ll hear the the Miller tune during the recorded phone menu. You’ll have to remember the 212 area code on your own, of course…