You know, I don't think it has anything to do with cost or $$$ at all.
The women explained to me that they look at the area code and if it isn't somewhat near the area code where you are 'supposed' to physically be present, they figure that they can't get in touch with you.
All they really need to do is add another field in their database that says Cell Phone Number. Viola! Then, the agents would know that you probably have that on you.