JSI Tip 9365. When you attempt to enable the telephony server on Windows Server 2003, you receive 'An unknown error occurred'?

When you attempt to enable the telephony server, you receive An unknown error occurred. 62791 if Windows Server 2003 is a member of a workgroup, or An unknown error occurred. 62795 if Windows Server 2003 is a member of a a Windows NT 4.0 domain.

This behavior occurs because the telephony server can only be enabled on a Windows Server 2003 that is joined to an Active Directory domain, because it needs to publish a SCP (Service Connection Point) entry in the Active Directory so that Windows XP and above clients can discover it.