The first call is the one you set the appointment on (or the confirming call you make the day of your appointmet if you booked it well in advance)and the second call is the one you make to her whern you have arrived at her address or hotel.  The second call let's her know you will be at the door in a coupel of minutes and you generally don't get her apt number or hotel room number until this second call.

This second call will sometimes be tough to do withouit a cell phone.  Good luck.