Lync 2010 cannot connect to the Lync Online service

You cannot connect to the Microsoft Lync Online service when you are using Microsoft Lync 2010. When you view Network Monitor, traces show multiple TCP SYNC requests for login.microsoftonline.com.

This issue occurs when the Microsoft Online Services Sign-In Assistant traffic does not go through the Microsoft Forefront Threat Management Gateway (TMG) firewall client, and a direct connection is attempted.

For example, this issue may occur in a scenario where all the following conditions are true:

• Proxy Server Automatic Discovery is not enabled.
• A proxy server is not configured in Internet Explorer.
• The Automatically detect settings option is not enabled in Internet Explorer.

To resolve this issue for Forefront TMG, create an application entry for�Msoidsvc.exe. To do this,�follow these steps:

1. In the left pane, click Networking.
2. Click the Network�tab. Under the�Tasks tab in the right pane, click Configure Forefront TMG Client Settings.
3. In the Forefront TMG Client Settings�dialog box, click�New.
4. In the Application Entry Setting dialog box, configure the following rules:
   
   
   Collapse this tableExpand this table

   Application	Key	Value
   msoidsvc	Disable	0
   msoidsvc	DisableEx	0

Note The same application settings can be applied to other firewalls. Additionally, your firewall server may require a firewall client to be installed on the end-user's computer.