A bit of history might shed some light on the practice.

Back in the days before the internet or the cell phone, many escort arrangements were made by phone calls to escort ads in various "entertainment" magazines which all major cities had.  In NYC it was the Village Voice, in Boston is was The Phoenix.

When you got a gal on the line, she would direct you to a phone booth at a certain location to call her back.  At that phone booth, she either was able to view you directly from her window (If the phone booth was outside.) or she would have a code written on the wall next to the phone booth that she would ask you to repeat.  (Mission Impossible had nothing on them.)

This way she could verify you and at least make sure that you were there and not a time waster.

Now with cell phones, these little security measures no longer hold water.

So, why the 2-call system, indeed?

I suppose it does cut down a bit on her location getting leaked out to some time wasters, but that's about it.

Now that I have a few incall meetings under my belt, I'm learning all about the "two-call" system, which seems pretty standard: You get an address maybe a day or so before the meeting, and then don't get an apartment or room number until you're physically standing in front of the incall location.  

I should add that I suffered no ill effects from providers knowing my room number several days before the actual meeting.

Client #1 is super excited for his date!  He decides to show up 1/2 hour early!

Many ladies will not come out to your hotel until they can verify that you are actually THERE.  Yes, time wasters and game players have sent many ladies on wild goose chases.    

How can you verify that I'm actually at my hotel before knocking on my door? I haven't given you my real name, so you can't call the hotel and ask for my room. You can't call the front desk and ask to speak to the gentleman in room ###. The best you can do is use the house phone to call before coming up, but by then you're already at the hotel, so what's the point?

Thank you Sola!

......I give the general area of my incall, and tell gentlemen to call me after they have parked.  I then give them my exact address/room number.  I never put my address or room number in an e-mail.  I do not text.

One gal gave me turn by turn directions...  I ended up in the same place, headed the opposite direction...  she was checking that I wasn't being followed by unmarked cars.

true name of the gentleman behind it.