Hi Jan,
You can leverage this config to achieve this requirement
Associating Multiple Extensions with a Mailbox
Up to two numbers can be associated with a mailbox:
•
Primary extension—For a Cisco CME system, this is an extension configured on the system and exists as an ephone-dn command statement in the Cisco CME configuration. For a Cisco CallManager system, this is a free-form field and no cross-checking is done between Cisco Unity Express and Cisco CallManager to ensure that it matches a valid extension on Cisco CallManager (although this is the intended use of the field).
• Primary E.164 number—This is any secondary number that you intend to associate with the mailbox. Its primary use is to map the subscriber's DID number to the mailbox so that calls arriving from the PSTN can enter the mailbox unaltered. As described in the "Calling into Voice Mail to Retrieve Messages" section, it can also be used for voice mail retrieval functionality; DID numbers can go through digit manipulation to match the extension before entering the Cisco Unity Express mailbox.
When a call arrives at Cisco Unity Express, the "called" (for leaving a message) or "calling" (for retrieving voice mail) number is compared with these two fields. If either one of them matches, then the mailbox is recognized at the destination for this call.
If you intend to map more than two numbers to a mailbox, you must use the digit manipulation features on the router, Cisco CME, or Cisco CallManager to adjust the number to one of the Primary Extension and Primary E.164 Number fields before the call reaches Cisco Unity Express.
http://www.cisco.com/en/US/docs/voice_ip_comm/unity_exp/design/design21/cuevmdes.html#wp1013248
Cheers!
Rob
