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After you configure Microsoft Windows Messenger to connect to a Session Initiation Protocol (SIP) communications service account, and then you try to sign in to a Microsoft Office Live Communications Server 2003 server, you experience the following symptoms in the following order:
When you click the Click here to sign in link, you are prompted for your sign-in name, your user name, and your password information.
When you type this information and then click OK, you receive the following error message:
401 - Unauthorized Signing in to SIP Communications Service failed because the sign-in name, username, or password is incorrect, or the authentication service is not compatible with this version of the program. If you have signed in correctly and the problem persists, contact your network administrator.
This problem occurs even though you have verified your password and typed your user name in one of the following formats:
Note These formats appear in the example in the Sign In to a SIP Communications Service dialog box.
This issue may occur if both of the following conditions are true:
Live Communications Server 2003 is configured to use the Kerberos authentication scheme.
You try to sign in from a computer where one of the following is true:
NetBIOS is disabled on the computer.
The computer is running Microsoft Windows XP Home Edition.
The computer is configured to run behind an Internet Connection Sharing device or behind another Universal Plug and Play (UPnP) Network Address Translation (NAT) device.
The computer is not joined to the same domain as the Live Communications Server computer.
In certain Live Communications Server topologies, you cannot successfully sign in by entering your credentials in the user principal name (UPN) format (firstname.lastname@example.org). Additionally, you may have to specify the fully qualified domain name (FQDN) together with your user name when you enter it in Universal Naming Convention (UNC) format to successfully sign in. For example, when you type your user name information in the Sign In to a SIP Communications Service dialog box, you may have to use the following format to successfully sign in
where domain.example.com is the FQDN of your domain, and where username is your user name.
To work around this problem, use either of the following methods.
Method 1: Specify the FQDN
Specify the FQDN when you type your user name in UNC format. For example, type the following in the User name box of the Sign In to a SIP Communications Service dialog box:
Method 2: Use NTLM Authentication
Configure the Live Communications Server home server to use the NTLM authentication scheme. To do this, follow these steps:
Start the Live Communications Server utility.
Expand Servers, right-click the server that you want to modify, and then click Properties.
Click the Authentication tab, click NTLM in the Authentication scheme in use list, and then click OK.