Found this on the AT&T site:
Equipment
If the equipment you purchased does not meet your expectations, simply return it either to a store or by mail within 30 days from the date the equipment was purchased or shipped. (Gift cards, Ring tone cards, and Apple branded equipment are excluded. See below.)
Apple Branded Equipment
All sales of original iPhone and refurbished iPhone after July 1, 2008 are final and cannot be returned for any reason. Original iPhone is covered by Apple warranty. AT&T will not accept returns for items purchased at Apple stores or at Apple.com. iPhone is not eligible for the Wireless Insurance program. Purchase of original iPhone will not impact upgrade eligibility.
http://www.wireless.att.com/cell-phone-service/legal/return-policy.jsp
Equipment
If the equipment you purchased does not meet your expectations, simply return it either to a store or by mail within 30 days from the date the equipment was purchased or shipped. (Gift cards, Ring tone cards, and Apple branded equipment are excluded. See below.)
Apple Branded Equipment
All sales of original iPhone and refurbished iPhone after July 1, 2008 are final and cannot be returned for any reason. Original iPhone is covered by Apple warranty. AT&T will not accept returns for items purchased at Apple stores or at Apple.com. iPhone is not eligible for the Wireless Insurance program. Purchase of original iPhone will not impact upgrade eligibility.
http://www.wireless.att.com/cell-phone-service/legal/return-policy.jsp