In the early 70s, we had 16 long distance telephone numbers and 8 local telephone numbers for the house. All on a single party line.
My parents wanted a private line, but it was less expensive to get all four lines of a party line, so they did that instead.
So that was four numbers. Let's call them xxx1, xxx2, xxx3, and xxx4. (I don't remember what they were.)
While the house is in Texas, the telephone service is out of Oklahoma.
The switching equipment wasn't all that great so we could use either the prefix for the Oklahoma side, 338, or the prefix for the Texas side, 339. And we could use either area code, 405 for Oklahoma (then) or 806 for Texas.
Thus, we could dial any of the following long distance:
806-338-xxx1
806-338-xxx2
806-338-xxx3
806-338-xxx4
806-339-xxx1
806-339-xxx2
806-339-xxx3
806-339-xxx4
405-338-xxx1
405-338-xxx2
405-338-xxx3
405-338-xxx4
405-339-xxx1
405-339-xxx2
405-339-xxx3
405-339-xxx4
Also, when placing a long distance call, the operator would come on the line and ask the number you were calling from so they could bill it correctly. That practice continued long after they fixed the above situation.