You place your first call to get the general location (name of hotel or cross street).  Once you arrive, you call again for her room # or apt. #.
This is really a question for the Newbie Board.

1 call, you make a call, setup appointment and get general area or hotel
2 call you get actual address or room

There are slight variations but pretty much the same

Then another example
1 call, you call make appointment and they give you all information needed to get there
2 call, to attorney because it was a sting and you got caught