Hi back darling Billcat, well you have nearly got it correct. Stage Manager, of course, would certainly let the cast know that the curtain is ready to go up (or pulled in smaller theatres), but the Callboy's job is to let each actor know 'during the course of a show' when their 'cue is due' so they don't miss it.
Extremely responsible job I can assure you.
As for call girl (was just trying to make a joke of it you understand) .. they did looked at me rather strangely, and didn't quite get the humour. Think I should have said in a more PC way .. Call person...
Glad you enjoyed the panto .. nowt like it is there ?