"Trying to talk a user through a procedure over the phone,"
Is the worst thing ever , it should be an absolute last resort
I once had to talk a Sales & Marketing guy on the other side of the Atlantic through patching a Unix binary using adb. (Very long story.) My initial remarks were "Only press the keys I tell you to, when I tell you to press them. This includes the return key. Do not press any key that I have not told you to press. Do not think or try to be helpful."