Exchange Unified Messaging (UM) introduced Outlook Voice Access (OVA). OVA lets UM-enabled users to access their Exchange 2007 mailbox using analog, digital or cellular telephones. And one neat feature of OVA is Directory Search, which lets you perform user search against the corporate Global Address List. If the desired contact is found, you then have the option to make a call directly to any of that user's phone numbers that are configured in Active Directory.
But wether you're using an UM Dial Plan to integrate with Office Communications Server (OCS), or wether there's a dial plan in place that integrates with a supported IP PBX or SIP gateway, it will be necessary to configure Dialing Rule Groups to have the option of making calls to outside telephone numbers. An easy way of doing this is by editing the dial plan properties, select the Dialing Group Rules tab, and then adding two Rule Groups: countrywide and worldwide, with an “*” as Number Mask and Dialed NumberThese two Rule Groups must also be added to the Dialing Restrictions of the UM Mailbox default policy.