I always have a hard time finding the APN list I should be using for any AT&T “4g” phone, so I thought I would post them here for easier reference. These came from the XDA forums and I take not responsibility for them. I’m just sharing them for all. I believe you need all 4 of them and you should set the AT&T US HSDPA to the default one in your APN manager.
Name: AT&T US
APN: wap.cingular
Proxy: wireless.cingular.com
Port: 80
Username: <not set>
Password: <not set>
Server: <not set>
MMSC: <not set>
MMS Proxy: <not set>
MMS Port: <not set>
MCC: 310
MNC: 410
Authentication type: <not set>
APN type: default,supl,agps,fota,dun
Name: AT&T US HSDPA
APN: phone
Proxy: <not set>
Port: <not set>
Username: <not set>
Password: <not set>
Server: <not set>
MMSC: <not set>
MMS Proxy: <not set>
MMS Port: <not set>
MCC: 310
MNC: 410
Authentication type: <not set>
APN type: default,supl,agps,fota,dun
Name: AT&T US Tether
APN: broadband
Proxy: wireless.cingular.com
Port: 80
Username: <not set>
Password: <not set>
Server: <not set>
MMSC: <not set>
MMS Proxy: <not set>
MMS Port: <not set>
MCC: 310
MNC: 410
Authentication type: <not set>
APN type: tether
Name: AT&T US MMS
APN: wap.cingular
Proxy: wireless.cingular.com
Port: 80
Username: <not set>
Password: <not set>
Server: <not set>
MMSC: http://mmsc.cingular.com
MMS Proxy: wireless.cingular.com
MMS Port: 80
MCC: 310
MNC: 410
Authentication type: <not set>
APN type: mms
Hopefully this will help anyone like me who is always searching for these after flashing a new ROM.