How do these work?  Does the lady actually call the other lady and ask about you?

She may or may not ask that.
A provider I saw asked the best way to contact my reference -- email, calling, or texting.
I think that calling is more personal and to the point since you can hear both voices.
I got the okay from my reference and everything was good to go.

she will contact at least one of your references.  As previously stated, she may ask you for the best way to contact your ref, unless she knows the provider and has talked to her before, in which case she already knows how to contact the other provider.

Swim

And other referring provider tells her that you are okay to see.

Usually it comes down to:

1.  Is he safe?

2.  Is he on time?

3.  Is he hygenic and clean?

4.  Does he pay without problems?

They don't usually get into session details, from what I understand.

The most of good providers make a screen and take every info seriously, and call or send an email to the providers that u use like a reference.... I'm for me, is I don't know that provider I check her too.. Sometime the people bring fake information and reference thinking that girl don't call to the references.