WOR New York 1920
KACL
MPR could refer to the call letters of Minnesota Public Radio.
A long time ago, when commercial radio was just starting, it was evident that the stations needed to have some regulation. One of the things that made sense to them, back then, was to have call letters starting with "W" be on the east part of the US, and call letters starting with "K" being on the west half.
Radio static letters : "EMI"
Verbal announcement of the station's call letters and location.
If you have a local radio station you like, try checking to see if it has a website (typically it will be the call letters of the station followed by .com).
We're confident that it must have been "5XT" ... the 28th licensed station in the United States ...licensed on March 16, 1922, and soon changed its call sign to "WKY", 930 AM in Oklahoma City.
The word "woap" is not an English word, except as the call letters of an inactive radio station, WOAP, in Michigan.
One is WACO in Waco, TX. I don't know of any others.
There are 36504 different possibilities.
Words don't have alphabets. They have letters. The first and last letters of a word od not have any special names in English.
Using only the first letters of a word to form a new word or phrase is called an acronym.