Bill W -When I was young, telephone numbers were just five digits. Then before I was a teen, they added a two-letter prefix. ST stood for Stillwell, PI was for Pioneer and RA was for Raymond, so if you told someone your phone number, you would say, "Call me at Pioneer 8-7432."
Five digits - how about one?
When our family lived in a small country town over 40 yrs ago our phone number was '2'.
My sister traveled to Europe where, at the time, phone numbers were enormous by Australian standards, and had great trouble convincing the local telephonists (now there's a redundant occupation) that a connection could be made with the name of the town followed by a single digit.