No problem Ray, if you get stuck there are many using the software that can help you when you get to that point. It's not a real difficult thing to do really.
Basically you're creating both of the setups one right after the other (adding both elements to the page in other words), then at full size you take the one you don't want to be seen, which in this case would be the Phone dialing setup, and set that element's Display setting to Display: None
Then shrink the page using the slider until you get to the phone sized screen size and in there you will want to now make the Phone dialing setup to be Display: Block (or whatever you need it to be, I would check the original before making it not display so you know what to change it to in the narrower sized screen settings). Now take the element that was showing in the full sized screen size, that you don't want to show in the phone sized screen and set that one to Display: None and that's it!
Now what happens is when the screen is full sized and all the way down until phone size, it's the normal phone number setup, and as soon as it hits the phone size, it will now show the dialing phone setup.
Hope that helps and as I said, if you need help when you're ready to give that a shot just holler and someone will be around to help out.