Hi Peter.
I live with Whipbirds around my house (in Robertson).
I am puzzled by what you mean a "reverse call".
Can you pls explain a little bit more.
There is a degree of variation, and sometimes the long drawn out "eeee" part of the call is dropped off, and they just do the whip crack.
Then the female will usually respond.
On rare occasions, the female calls, presumably to check what her bloke up to. But I have never heard a female call, being responded to by the "eeeee chop" call (which to me would be a full "reverse call").
Incidentally, in my local area, the female response is normally 3 calls, not the standard two which seems normal in Canberra and the Brindabellas.
As I have been typing this, I have heard a Whipbird outside calling.
Several times he gave the full "eeeee chop" call and some times just the "chop" call.
His female partner has failed to do the answering call, so he is presumably getting anxious now.