Network codes

A man and his wife agreed on a code to use in front of their kids when they want to have s*x. The code is: “Making a call.”
One day the man ask his son to tell his mother, that dad wants to make a phone call.
The boy returns to his dad, that mom says she is out of order.
Then he ask him to tell her, that dad will go outside to make a phone call.
The boy returns, that mom says, “If you do so, she will open a central telephone station in the house.”