I have worked at my voice and I have been told by several people that I sound very much as a woman. And I am in retail, dealing with the public daily. I have never gotten the reaction from peeps that I have be clocked because of my voice.
But it has been practice, practice, practice, practice, practice and more practice. The phone is the best because they have no idea, just a name. If the name and voice match, it 'Yes Ma am', 'I understand Miss' etc.