To cope with a day when I’m overwhelmed with e-mail to answer, an old Calvin and Hobbes strip salted away for just such days:
They exchange greeting hellos, and then the caller, detecting that the phone has been answered by a child, shifts to an indirect speech act designed to have the child get an adult — the caller specifically asks about their mother — to come to the phone: instead of (directly) asking Calvin to call his mother to the phone, they ask (politely) if his mother is home, assuming that Calvin will understand that they’re asking this because they assume she’s home and they want to talk to her, so they want him to turn the call over to her
The overall story here doesn’t depend on the phone being answered by a kid. It’s enough that the caller recognizes that the person answering the phone is not the one they want to talk to. In which case they could ask for them indirectly: Is Marcia home / in? (this being one big step of indirection beyond the conventionally indirect question May / Can I talk to Marcia?).
The crucial step in dealing with the yes-no question Is X home? is recognizing that because a literal understanding of it would be bizarre — why would some random caller need to know if X is home? — the caller must have some other motive in asking it. And on from there. But that’s where Calvin runs aground.
Well, that’s a lot for a little kid to work out in less than a second on the phone (and Calvin is not a patient or especially cooperative child). I actually remember being taught, explicitly, that if a phone caller, or someone at the door, asked if my mother was at home, that meant they wanted to talk to her, so I should get her. I imagine I could have worked this out eventually, but it might have taken some misfires for me to get the point.
