Some organizations will deploy LiveMeeting either without the existence of OCS, or without OCS Audio/Video Conferencing being enabled. By default, the conferencing addin for outlook has a Schedule A Conference Call button regardless of the environment you are connecting it to.
There is a registry entry that can be used to disable this button:
1. Locate and then click to select the following registry subkey:
Note Use this subkey for x86-based systems. If you are running a x64-based system, locate and click the following subkey:
2. After you select the subkey that is specified in step 3, point to New on the Edit menu, and then click DWORD Value.
3. Type RemoveConferenceCall, and then press ENTER.
4. Right-click RemoveConferenceCall, and then click Modify.
5. In the Value data box, type 1, and then click OK.
6. On the File menu, click Exit to close Registry Editor.
If you wish to remove this setting, simply change the Value to 0 and the button will be available again.
A full list of livemeeting registry keys can be found here: http://technet.microsoft.com/en-us/library/dd637135(office.13).aspx