For each new instance of Lync Online, federation with other organizations and with public IM providers is by default disabled for the organization. The following steps are used to enable federation and public IM:
1. Log on to the Office 365 Portal.
2. On the main page, click the Admin tab at the top, and then select Lync from the drop-down menu to open the Lync Admin Center.
3. On the left side, click Organization, and then click on the link for External communications at the top.
4. At the External communications page, under External access, use the drop-down menu to select the domain federation option that meets the organization’s policy for communication with external organizations. If the organization ...