Dial-Up Networking Error Codes

Here's a list of common DUN error codes and their definitions.

Error 602: The modem is being used by another Dial-Up Networking connection or another program. Disconnect the other connection or close the program, then try to connect again.

Error 629: You have been disconnected from the computer you dialed. Double-click the connection to try again.

Error 630: The computer is not receiving a response from the modem. Check that the modem is plugged in. If necessary, turn the modem off, and then turn it back on.

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 645: Internal authentication error.

Error 650: The computer you're dialing is not responding to a network request. Check your server type setting in the properties of the connection

Error 666: Device not ready.

Error 667: The Dial-up Networking information in the registry is corrupt. To restore it shut down the computer and restart.

Error 676: The line is busy. Try again later.

Error 678: The Computer you're dialing is not answering. Try again later.

Error 680: There is no dial-tone. Make sure your modem and phone line are properly connected.

Error 691: The computer you're dialing in to cannot establish a Dial-Up Networking connection. Check your password, and then try again.

Error 720 or 731: Dial-Up Networking could not negotiate a compatible set of network protocols you specified in the Server Type settings. Check your network configuration in the control panel and try again.

Error 745: An essential file is missing. Re-install Dial-Up Networking.

Errors without Codes

Dial-Up Networking could not negotiate a compatible set of network protocols you specified in the Server Type settings. Check your network configuration in the control panel and try again.

Dial-Up Networking could not complete the connection to the server. Check your configuration and try the connection again.

The Microsoft Dial-up Adapter is not configured to work with the current network configuration. Check your server type and network configuration in the Control Panel then try the connection again.