Good question. No, Diane - you would still have service - the phone will kick over to EDGE. I've quoted the below directly from the AT&T website:
In areas where the 3G network is not available, customers will continue to receive service on the AT&T EDGE network, when coverage is available.
The AT&T EDGE network is available in more than 13,000 cities and towns and in areas along 40,000 miles of highways. It provides average data speeds between 75-135Kbps.
