Error 638 may mean that the number being dialed is wrong or not filled in at all, or that somehow that the Operator-Assited Dialing option has been checked for dial-up connections.

Basic Troubleshooting - Always complete these steps prior to Advanced Troubleshooting

1. Pull the battery out of the phone while it is disconnected from the computer and charger
2. Restart the computer
3. Verify the Phone is capable of browsing the internet on the phone
   Note If the phone is unable to browse itself, contact your wireless provider.
4. Verify the connection and settings are correct by following the Connection Setup again to check the settings
5. Test the connection again

Advanced Troubleshooting

Verify the Dial-up number if filled in and correct:

1. On the computer go to
   
   • Windows XP - Start > Control Panel > Network Connections
   • Windows Vista - Start > Control Panel > Network and Sharing Center > Manage Network Connections
   • Windows 7 - Start > Control Panel > Network and Sharing Center > Change Adapter Settings
     
2. Right click the Dial-up Connection then select Options
3. Verify the dial-up number is *99#
4. Test the connection if a change is made.

Verify the Dial-up number if filled in and correct:

1. On the computer go to
   
   • Windows XP - Start > Control Panel > Network Connections
   • Windows Vista - Start > Control Panel > Network and Sharing Center > Manage Network Connections
   • Windows 7 - Start > Control Panel > Network and Sharing Center > Change Adapter Settings
     
2. At the top click the Advanced menu
3. Uncheck Operator-Assisted Dialing if it is checked (Click it to uncheck)
   Note If you do not see a menu or Advanced, press the Alt key on the keyboard.
4. Verify the dial-up number is *99#
5. Test the connection if a change is made.