Hi
Not much detail in your request there; I'm assuming you mean use the UM feature of Exchange? You didn't specify which version of Exchange; be aware that Exch2007 doesn't support MWI properly so you need a third party product to get MWi working if that is important.
Configuration is pretty simple and is detailed here (for 2010, but there's not much difference between that and 2007):
http://www.microsoft.com/downloads/en/confirmation.aspx?FamilyID=d5db0297-7850-4f52-b965-b8006b4c05f5
Regards
Aaron
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Aaron
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