"Here are the steps to set this up if your a a Cingular customer (they have a great support website at http://www.cingular.com/support/):
Click on the Apple menu.
Select System Preferences...
Click on Network.
NOTE: A dialog box may appear at this point, indicating a new device has been detected. This usually happens when configuring a USB connection for the first time. Press OK to continue if this occurs.
Select the connection to be configured and press Configure.
NOTE: This is typically "Bluetooth" for Bluetooth connections, or the name of the phone for USB connections, such as "Motorola Phone (V600)".
Select Using PPP in the "Configure IPv4" drop down menu.
Click Configure IPv6.
Select Off in the "Configure IPv6" drop down menu, then press OK.
Click the PPP tab.
Enter the following information:
CINGULAR WIRELESS CUSTOMERS:
Account name: [email protected] or [email protected]
Password: CINGULAR1
Telephone Number: isp.cingular or *99***1# or *99# or *99***3# (dialing string varies by device and OS version)
Service Provider: Optional, but it is recommended to recognize the connection.
FORMER AT&T WIRELESS CUSTOMERS:
Account Name: Leave Blank
Password: Leave Blank
Telephone Number: *99***1# or *99# or *99***3#
Service Provider: Optional, but it is recommended to recognize the connection.
Click PPP Options...
Ensure that the following boxes are unchecked.
Send PPP echo packets.
Use TCP header compression.
Connect using a terminal window (command line).
Press OK.
Select the Modem or Bluetooth Modem tab, depending on the type of connection being configured.
Select the appropriate modem script in the "Modem" drop-down menu.
Uncheck Enable error correction and compression in modem.
Uncheck Wait for dial tone before dialing.
Click Apply Now."