Free/Busy error: Request timed out.Call stack.No callstack available

  

Trying a Free/Busy test between two companies which uses the Microsoft Federation Gateway as trust, I noticed that Free/Busy was not bringing the information as it should. I performed a check in OWA to see if any error messages were generated, and in fact I found the following error: System.Web.HttpExceptionException message: Request timed out.Call stack.No callstack available

Using Fiddler and testing with Outlook, I got a different log:

Failed to communicate with https://login.microsoftonline.com/extSTS.srf., Inner exception: Unable to connect to the remote server

Troubleshooting:

As a method of troubleshooting, I ran a Test-FederationTrust from Exchange Server. For those who do not know, this command let does a series of checks in the Microsoft Gateway’s trust and can also fixe some issues. The result brought me two errors message, in FederationMetadata and TokenRequest.

Then I decided to run the Get-FederationTrust | Set-FederationTrust -RefreshMetadata -Verbose It should update expired certificates used by the trust

The output shows clearly that the problem regards network. There was some URL which Exchange should be able to access, but the firewall or proxy denied the connection. The URL that the above log showed as not accessible was the https://nexus.microsoftonline-p.com/FederationMetadata/2006-12/FederationMetadata.xml

Resolution:

In order to fix the issue, I was able to find this article which tell us a bunch of addresses that must be opened to the Exchange talks with Microsoft Federation Gateway:

207.46.150.128/25

207.46.164.0/24

*.microsoftonline-p.com

*.live.com

*.microsoftonline.com

*.microsoftonlinesupport.net

Then I was able to run the Get-FederationTrust without issues

And the Free/Busy starts to work like a charm and the Request timed out.Call stack.No callstack available goes away: