This is a VERY over-used term.  What exactly does it mean?

It means once you have set an appointment with her, you will call her and she will give you directions to the general vicinity of her location (one call). Once there, she will have you call again and give you the specific location (second call).

If you're really unlucky, you make one call to obtain general information, one call to set an appointment, one call to confim the appointment, and finally one call from the street corner to obtain the apartment/room number information!

The calls to make the appointment don't count.  #1 for the general vicinity, #2 for exact address, apt. number, or room number if a hotel.

I know the calls to get information and confirm the appointment are not included in the "2 call system"...my attempt to inject a little humor!