The Receptionist

From Muppet Wiki

The Receptionist was used in The Muppet Show: Sex and Violence pilot. She had to deal with characters like Gluttony and Lust when the Muppets were holding auditions for their Seven Deadly Sins pageant. She had a brief "romance" with Lust in the show.

The character was never seen, but she was heard frequently through the show talking to Nigel, Sam the Eagle, and Floyd Pepper over the intercom.