On a computer that is running Microsoft Exchange Server 2007, Unified Messaging-enabled user calls Outlook Voice Access (OVA) to play a voice mail message. However, there is a delay before the voice mail message is played.
The delay is caused because OVA checks the Caller ID against every entry in the personal contact list of the user. This check continues even after the caller information is established. For example, if the user has 100 items in their personal contact list, the delay may be 10 seconds or longer.
To resolve this problem, install the following update rollup:
972076 Description of Update Rollup 2 for Exchange Server 2007 Service Pack 2
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.