These options are I believe found under the Apple Menu > System Preferences > Network. Then click on your internal modem and the last tab should be called "Modem". Clicking Sound Off hopefully will get right of your first question.
I believe what your asking for the second feature is how to turn this back on. To do that click on the "PPP" tab and then on the button "PPP Options..." the 2nd check-box from the top should be what you are looking for.
Hope this helps