Prevent callers without a caller ID from leaving a voice message

Exchange 2013

Applies to: Exchange Online, Exchange Server 2013, Exchange Server 2016

Topic Last Modified: 2013-02-22

You can allow UM-enabled users to receive voice messages from anonymous callers or prevent them from doing so. By default, when users are enabled for Unified Messaging (UM) and voice mail, they can receive calls that are anonymous and don't contain caller ID information.

In most cases, calls received by Exchange servers contain a caller ID that can be used to determine the source of the incoming call. However, incoming calls may not include caller ID information for the following reasons:

  • Your organization's telephony equipment is configured not to include caller ID information.

  • The incoming call is from a mobile or external telephone.

  • The caller has disabled caller ID on their telephone.

Because the AnonymousCallersCanLeaveMessages parameter is enabled by default, a UM-enabled user can receive a voice message even if caller ID information isn't included. If the AnonymousCallersCanLeaveMessages option is disabled, and the UM-enabled user receives a call that doesn't include a caller ID, the call will be identified as anonymous, and the UM-enabled user won't receive a voice message.

For additional management tasks related to users who are enabled for voice mail, see Voice mail-enabled user procedures.

  • Estimated time to complete: 2 minutes.

  • You need to be assigned permissions before you can perform this procedure or procedures. To see what permissions you need, see the "UM mailboxes" entry in the Unified Messaging permissions topic.

  • Before you perform this procedure, confirm that a UM dial plan has been created. For detailed steps, see Create a UM dial plan.

  • Before you perform this procedure, confirm that a UM mailbox policy has been created. For detailed steps, see Create a UM mailbox policy.

  • Before you perform this procedure, confirm that the user's mailbox has been UM-enabled. For detailed steps, see Enable a user for voice mail.

  • For information about keyboard shortcuts that may apply to the procedures in this topic, see Keyboard shortcuts in the Exchange admin center.

Having problems? Ask for help in the Exchange forums. Visit the forums at Exchange Server, Exchange Online, or Exchange Online Protection..

This example prevents UM-enabled user from receiving voice messages from calls that don't contain caller ID information.

Set-UMMailbox -Identity -AnonymousCallersCanLeaveMessages $false