Good question.
I can’t find out how, exactly. It might have to do with someone in the soldiers family that live in the same district as Rep. Wilson. Whether Wilson instigated a request to the family to listen when and if a the call would come, or a family member tipped her off is unknown at this point, at least to me. Wilson listened to the call in her limo. I would hate to think that someone in the White House got her connected.
Thanks Karl, It has been bothering me how she was able to listen to a “private” phone call from the President.