Set up voice mail for users in Exchange Online
After you've connected your telephony network or integrated Microsoft Lync Server with Exchange Unified Messaging (UM) and created and configured the required UM components, you'll need to set up voice mail for your users.
When you're enabling users for voice mail, you'll need to link the user to a UM mailbox policy. UM mailbox policies are used to apply common settings to a group of UM- enabled users. These settings include PIN policies, outbound calling restrictions, text to send with messages, and other related settings. You can either use a default UM mailbox policy or create and customize a UM mailbox policy based on the needs of your organization.
Setting up voice mail for users
Before you enable users for UM, you must consider the type of dial plan to use, the extension numbers that will be used, and determine what PIN policies, Outlook Voice Access, and other features you'll allow users to have access to. For details, see Voice mail for users.