[Archived for posterity because I don't have this anymore. Yeah it was Very Nice not having to pay big bucks just to be able to have Internet anywhere the phone had bars.]
AT&T usb tethered modem settings
(from linux installation)
Mobile Broadband
Basic
Number: *99#
Username: WAP@CINGULARGPRS.COM
Password: []
Advanced
APN: WAP.CINGULAR
Network: []
PIN: []
PUK: []
PPP Settings
Allowed Authenication Methods:
EAP, PAP, CHAP, MSCHAP, MSCHAP v2
Compression:
Use Point-to-Point Encryption (MPPE): no
Allow BSD data compression: yes
Allow Deflate data compression: yes
Use TCP header compression: yes
Echo:
Send PPP echo packets: no
IPv4 Settings
Method: Automatic (PPP)