Exchange Server 2010: Why can't I access Outlook Contactfolders, calendar synchronisation or voicemail query over MAPI?

If a Exchange Server 2010 is used with the Client Access Server (CAS) role, you need to make the following adjustments to the settings at XPhone Server if you want to use the functions mentioned in the title:

1. Shut down the XPhone Server service
2. Open the XPhone Connect Server Manager. Under "Tools" you'll find "Atlas.xml". For XPhone UC V4 open the Windows Explorer, navigate to the XPhone Server program directory and open "atlas.xml" with the Editor.
3. Add the following entry before the entry "</configuration>: <Exchange CAS="exchangecas"></Exchange>
Now it should look like this:

<configuration>

...
<Exchange CAS="exchangecas"></Exchange>
</configuration>
 
4. Please replace the sample value "exchangecas" with the hostname (not fully qualified) of the Exchange.
5. Save the file and start the XPhone Server service.