Question about "Movie Night" (S.5): "That number in New Jersey, KLondike 5-4433!"

I get that KL5-4433 is a fictitious phone number (555-4433). What I don't get is the context of Hawkeye's joke.

Is he pretending to emcee a call-in radio music program? (Did they have those in the Forties or Fifties?)

Or is it something else?