CmdID / PowerShell / Cmdlets / Enable
Enable-UMService
Use the Enable-UMService cmdlet to set the status of an Exchange Server 2010 Unified Messaging (UM) server to enabled. Exchange PowerShell reference
From the Exchange PowerShell reference 4 parameters Its page in the reference
Parameters
-IdentityThe Identity parameter specifies the Exchange 2010 UM server that you want to enable.-Confirm, -cfThe Confirm switch specifies whether to show or hide the confirmation prompt.-DomainControllerThe DomainController parameter specifies the domain controller that's used by this cmdlet to read data from or write data to Active Directory.-WhatIf, -wiThe WhatIf switch shows what the command does without making any changes.