Another thing we could do was dial a 3 digit number, hang up and get back a "test ring".
My parents didn't like it if I was "just going out". They usually wanted a reason - playing ball, going to the movies, etc. Just "going out" could apparently lead to trouble. (They were right)
To avoid the inevitable questions, I'd dial the ring-back number, answer the phone and say something like "Hi Greg, what's up?... Meet you at the bowling alley? Sure. See you soon!"