Exchange 2007 and Exchange 2010 allow you to configure different event logging levels for all Exchange services.
I commonly have to enable more detailed Exchange UM logging on UM servers to troubleshoot call flow issues, so here is a quick reference of how to do this.
First off, here is the technet reference to doing this for all services:
In Exchange 2007, you must do this through Powershell, Exchange 2010 however is available right in the Exchange MMC.
For Exchange 2007:
Start by opening your Exchange Management Shell
The following powershell commands are required for the Exchange UM services
set-eventloglevel -identity “MSExchange Unified Messaging\UMWorkerProcess” -level Expert
set-eventloglevel -identity “MSExchange Unified Messaging\UMCore” -level Expert
set-eventloglevel -identity “MSExchange Unified Messaging\UMManagement” -level Expert
set-eventloglevel -identity “MSExchange Unified Messaging\UMService” -level Expert
set-eventloglevel -identity “MSExchange Unified Messaging\UMClientAccess” -level Expert
set-eventloglevel -identity “MSExchange Unified Messaging\UMCallData” -level Expert
In Exchange 2010 the same powershell commands will work, however, if you are more comfortable with the UI, you can do it directly in the Exchange MMC.
First open the Exchange Management Console
Expand your On-Premise Organization and select Server Configuration
Select your UM server from the list of available servers, and you will notice on the right hand side, under Actions for that server you will have Manage Diagnostic Logging Properties
Select Manage Diagnostic Logging Properties and you will be prompted with a full list of services on your Exchange server to manage. Expand MSExchange Unified Messaging, for each service you wish to raise the level, select that service, and then select the option for whatever level you wish to enable. Expert is typically a good level to have if dealing with UM.
Once you have configured all of your service levels, choose configure. This will basically execute the Powershell commands listed above and confirm Completion.