How are eunuchs and courtesans related?

I'm in a play called A Funny Thing Happened on the Way To The Forum, and I'm playing a courtesan. In the "whore house" that I live in, the eunuchs seem to be almost like servants to the owner of the house and the courtesans. I just don't understand why men without genitalia are necessary in a whore house. Can anyone give me an answer to this? Also, the play takes place in ancient Rome.