In the past when I've done Outcalls to Hotels (agency and independent), I end up giving my name and room number to the person, who then calls the front desk and forwards the call to the room phone.
This accomplishes two things:
- It establishes that I'm actually in the room
- It acts as a form of ID screening, as the Hotel had to view my ID and Credit Card prior to giving me the room
If one wants anonymity, one does not do Outcalls. One does Incalls with a provider or agency that does not require ID.