Use the following procedure to enable a Lync Online user for Exchange UM:
1. Log on to the Office 365 Portal.
2. On the left side of the main page, click Users and Groups.
3. At the Users and Groups page, select the check box for the user account to be enabled for Exchange UM; then, under Quick steps on the right side of the screen, click on Edit Exchange properties.
4. On the left side, click Mailbox features.
5. Under Phone and Voice Features, click the Enable link under Unified Messaging: Disabled.
6. At the Enable UM mailbox screen, click Browse, and then select the SIP URI dial plan previously created. Click OK, and click Next.
7. In the Extension Number field, enter the full phone number for the user, which ...