The song’s title is derived from the now-defunct use of telephone exchange names in telephone numbers. In this case, the significant portions of the exchange name were the first two letters of “Beechwood” (BE), and the remainder of the number. In conventional modern use, this telephone number would be 234-5789.
“Beechwood 4-5789” is a song written by Marvin Gaye, William “Mickey” Stevenson and George Gordy. It was a 1962 hit single for the Motown girl group The Marvelettes on Motown’s Tamla subsidiary record label. The song became a hit again when it was covered by the pop duo The Carpenters in 1982. Wiki