Allow Message Waiting Indicator (MWI) on a UM IP gateway in Exchange Server

Applies to: Exchange Server 2013, Exchange Server 2016

You can allow or prevent voice mail notifications to users for calls received by a Unified Messaging (UM) IP gateway. If you enable this setting, the UM IP gateway can receive and send SIP NOTIFY messages for users. Message Waiting Indicator (MWI) is enabled by default and allows message waiting notifications to be sent to users, but you can turn it off depending on your needs.

A message waiting indicator notifies a user about a new or unheard voice message. It appears in the Inbox in clients such as Outlook and Outlook Web App. It can also be a text (SMS) message sent to a registered mobile phone, an outgoing call made from an Exchange server to a number that's been configured for playing new messages, or a lighted lamp on a user's desktop phone.


MWI notifications can also be enabled and disabled on a UM mailbox policy for a group of users.

For additional management tasks related to UM IP gateways, see UM IP gateway procedures.

What do you need to know before you begin?


Having problems? Ask for help in the Exchange forums. Visit the forums at Exchange Server.

Use the EAC to allow Message Waiting Indicator

  1. In the EAC, navigate to Unified Messaging > UM IP Gateways, select the UM IP gateway you want to change, and then click Edit Edit icon..

  2. On the UM IP Gateway page, select the check box next to Allow message waiting indicator.

  3. Click Save.

Use the Shell to allow Message Waiting Indicator

This example allows the message waiting indicator to appear for users who are associated with the UM IP gateway named MyUMIPGateway with an IP address of

Set-UMIPGateway -Identity MyUMIPGateway -Address -MessageWaitingIndicatorAllowed $true