The differences between irritation, aggravation, and frustration

A boy asks his father to explain the differences between 

irritation, aggravation, and frustration.
    
Dad picks up the phone and dials a number at random. When the 
phone is answered he asks, "Can I speak to Alf, please?"
     
"There's no one named Alf here."  The person hangs up.
    
"That's irritation," says Dad.

He picks up the phone again, dials the same number and asks for 
Alf a second time.
    
"No -- there's no one here named Alf. You have the wrong number.
If you call again I shall telephone the police." End of 
conversation.

"That's aggravation."
    
"Then what's frustration?" asks his son.
    
The father picks up the phone and dials a third time:
"Hello, this is Alf.  Have I received any phone calls?"