When we moved to a new town, when I was a kid, we learned that if a given number was free, you could request it as your phone number. But you had to know it was

When we moved to a new town, when I was a kid, we learned that if a given number was free, you could request it as your phone number. But you had to know it was free by dialing it and getting a response saying so. My sister started trying memorable ones and tried [### - ### - 1234] (first 7 digits withheld for privacy reasons). That was the local fire department. 911 would have gone to the same phone. She hastily apologized. Later she learned that "4000" was free, and my parents have used that phone number for 20 years now.