Knock knock. Who's there? Pane

Pane who? I'm having a glass-half-empty relationship with you, it's a window of opportunity to change.

Knock knock. Who's there? Frank.

Frank who? Frank you very much for opening the door!

Knock knock. Who's there? Byte.

Byte who? I'm having a little trouble processing your question.

Knock knock. Who's there? A pause.

A pause who? No, just a pause. It's not a person.