Norrell would never answer his own phone, that is what he hires people for.

He is snippy on the phone, impatient at having been interrupted and wanting to know whatever is it that Childermass is calling him for! At the confirmation that it is Nancy, however, that she is all soaked through and in trouble with Fagin -- oh, that gets his attention! Why is she still down there, then! Bring her up, so she can dry out by the fire! Bring her some towels and a hot drink! Be quick about it, of course! Oh, if she is in such a state she is sure to be in need of help! She is just a girl, Childermass, he is sure you can handle her!