What The Errors Are
Also see this : http://support.microsoft.com/support/kb/articles/q163/1/11.asp
The above is a list of the RAS error codes and meanings, but does not seem to be a list of the actual messages displayed by Dial-Up Networking, at least in Win9x.
Article ID: Q188189
Error 172: (no server assigned) the request is not seen on the network.
Error 602: The modem is being used by another Dial-up Networking connection.
Close the other connection, and then try again.
Error 629: You have been disconnected from the computer you dialed.
Double-click the connection to try again.
Article ID: Q190554
Error 630: The computer is not receiving a response from the modem.
Check that the modem is plugged in, and if necessary, turn the modem
off, and then turn it back on.
Article ID: Q190554
Article ID: Q189388
Article ID: Q191444
Error 633: The modem is not installed or configured for Dial-Up
Networking. To check your modem configuration, double click the Modems
icon in Control Panel.
Error 650: The computer you're dialing in to does not respond to a network request.
Check your server type settings in the properties of the connection. If
this problem persists, check with your network administrator.
Error 678: The computer you are dialing is not answering.
Error 680: No Dial Tone.
Error 691: The computer you are dialing in to cannot establish a Dial-Up
Networking connection. Check your password, and then try again.
Error 720: Dial-Up Networking could not negotiate a compatible set of network
protocols you specified in the Server Type settings.
Article ID: Q190554
Article ID: Q174579
Error 745: An essential file is missing. Re-install Dial-Up Networking.
What The Errors Mean
Windows 98 Error Codes
* Dial-Up Networking: Error 602 The modem is being used by another Dial-Up Networking connection.
If there are multiple modems set up on the computer make sure the dialer is looking at the correct modem. Check for any fax software or any other software that might be trying to use the modem. You may need to look in the start menu programs to see what is being loaded on startup; and close anything that might be holding the modem open. You can also restart the computer and hold down the control key when you see the text that says Starting Windows 98. Doing a Ctrl, Alt, Delete and ending task on everything except Explorer and Systray should release the modem too.
* Dial-Up Networking: Error 629 You have been disconnected from the computer you have dialed.
There are several reasons why a customer could receive this error message. Be sure to verify that they are using the correct username and password. Check to see what phone number they are dialing and make sure it isn't set to use area code and dialing properties. You should also verify TCP/IP settings. Have the customer take out the password and try to connect without it; if they aren't prompted for password delete TCP/IP and reinstall. It might also be necessary to remove and reinstall Dial-Up Networking.
* Dial-Up Networking: Error 630 The computer is not receiving a response from the modem.
Verify that the dialer is looking at the correct modem. If the modem is internal, restart the computer and see if the modem will respond. If the modem is external; turn the modem off and then back on. You may want to check if they have an init string entered in the extra settings box. If so, take out the string and restart the computer. As a last resort go into modem control panel, click the diagnostic tab, click the port corresponding with the modem and click more info. If you don't receive a response it may be necessary to remove and reinstall the modem. Use your best judgement when working with a customers modem and make sure they have any needed software before doing so.
* Dial-Up Networking: Error 635 Cannot establish the Dial-Up Networking session.
Go to My Computer, Dial-Up Networking and go the properties of the MCN icon. Click the Server Type tab and verify settings. Be sure that Enable software compression and TCP/IP are the only ones selected. Click the TCP/IP settings button and verify settings there. Click OK to save changes.
* Dial-Up Networking: Error 645 Dial-Up Networking could not complete the connection to the server.
Go to My Computer, Dial-Up Networking and go to the properties of the MCN icon. Click the server type tab and take the check out of the box that says Require encrypted password. Have the customer try to connect again.
* Dial-Up Networking: Error 650 The computer you're dialing into does not respond to a network request. Go to My Computer, Dial-Up Networking and the properties of the MCN icon. Click on the server types tab and make sure the settings are as they should be. You may also want to check DNS settings in the network control panel.
* Dial-Up Networking: Error 676 The line is busy.
There are a couple reasons a customer may get this error message. The first could be that the number is actually busy. Check the portmaster they are dialing or try dialing the access number yourself. If the number isn't busy you should check their settings. Double check that the number they are dialing is the correct one for their area. You may also want to see if the customer needs to dial a prefix to get an outside line.
* Dial-Up Networking: Error 691 or 718 The computer you are dialing cannot negotiate a dial-up networking connection.
Verify that the customer is using the correct username and password. You may also want to go to My Computer, Dial-Up Networking, and the properties of MCN. Click on the server type tab and make sure that log onto network isn't checked.
* Dial-Up Networking: Error 720 Dial-Up Networking could not negotiate a compatible set of network protocols you specified in the Server Type settings.
Go to My Computer, Dial-Up Networking and the properties of the MCN icon. Click on the server type tab and click on the TCP/IP settings button. Verify the TCP/IP settings and click ok. You will also want to verify that both Dial Up Adapter and TCP/IP are installed in the network control panel. After verifying that the components are installed you will need to verify the settings and click ok.
* Dial-Up Networking: Error 742 The computer you're dialing in to does not support the data encryption requirements specified.
Go to My Computer, Dial-Up Networking and the properties of the MCN icon. Click the server type tab and make sure Require encrypted password isn't checked.