The UM troubleshooting tool is a diagnostic commandlet which helps Exchange UM administrators to identify mis-configurations in telephony equipment and Exchange 2010 SP1 Unified Messaging settings. It emulates calls and runs a series of diagnostic tests, stating the reason and possible solutions for issues that have been detected.
To get started with the tool type the following:
Get-help Test-ExchangeUMCallFlow -detailed
You can download the tool from here: