Q.

How do I resolve a 401 error with Telephony Application Services?

A.

In Microsoft® Speech Server (MSS) 2004 R2, requests from Telephony Application Services (TAS) to Speech Engine Services (SES) may result in the following error, seen in the Application Log in Event Viewer.

"A call failed because SES URL 'http://<application>/SES/Lobby.asmx' could not be found. Please ensure that the TAS SpeechServer property is correct. The following error was returned: 80131509: 'The request failed with HTTP status 401: Unauthorized. (System.Net.WebException)'."

Internet Information Services (IIS) authentication settings may be changed unexpectedly by updates. This may require a manual change to restore the desired settings. See the following procedure.

To reset Windows authentication:

1. On the Windows taskbar, click Start, right-click My Computer, and then click Manage.
2. In the Computer Management dialog box, in the tree view pane, expand Services and Applications, expand Internet Information Services, and then expand Web Sites.
3. Under Web Sites, browse to the MSS application directory, right-click the application directory, and then click Properties.
4. In the application's Properties dialog box, on the Directory Security tab, locate Authentication and access control, and then click Edit.
5. In the Authentication Methods dialog box, locate Authenticated access, clear the Integrated Windows authentication check box, and then click OK.
6. Once again, in the application's Properties dialog box, on the Directory Security tab, locate Authentication and access control, and then click Edit.
7. In the Authentication Methods dialog box, locate Authenticated access, and then select the Integrated Windows authentication check box.
8. Click OK twice to return to the Computer Management dialog box.

Clearing Integrated Windows authentication and applying the change, and then setting it back and applying the restoration, resets IIS so that Lobby.asmx is accessible.