As of April 2015, the telephone number for the customer service department for AT&T Wireless that also fields complaints is 800-331-0500. Agents man this line seven days a week, during the hours of 7 a.m. to 10 p.m. in the local time where the customer resides.
According to the AT&T website, most complaints receive swift handling when customers use the phone number listed; however, if a customer wants to file a formal complaint against AT&T, clear instructions and downloadable forms are available via the AT&T website at ATT.com under Support. Customers in Alaska displeased with AT&T Wireless can call 800-390-2782 to register a formal complaint. .