Well after months of looking and reading i have finally found the at&t settings. This really works unlike the others! iTS BEEN TESTED AND SUCCEEDED!!!
MMSC: http://mmsc.cingular.com
Proxy: wireless.cingular.com:80
APN: wap.cingular
Username: [email protected]
Password: CINGULAR1
and if it doesn't work you'll probably have to change your imei number with ZiPhone to a phone that can recieve pic messaging but u can't use that phone while you're using the hacked iphone.