Hold the Line: As telephony grew, so did a workforce of switchboard operators
daily.jstor.org
daily.jstor.org
The real impetus to Strowger is that the other undertaker in town was married to the phone operator.* So when someone called and said they had a dead body strowger didn't get the call often even if he was asked for by name.
* Often the switchboard was just in someone's house or on their porch, and phone service was just available for a few hours a day, when the owner was willing to sit around and wait for someone to call. So no service while cooking, or at mealtime, or at night.