I know when we went we first checked w/AOL. (you can put in the area code, then pick the city at the sign-in part). Then we called the front desk to make sure what ones were local and not toll. I think they might have told us which ones to use. There were specific Lake Buena Vista #'s if I remember correctly. I think Kissemmee works as well.
Local calls aren't free, from what I recall.
HTH!