We created a simple web console for adding users, domains or groups. You also can disable users temporary, change passwords or publish contact informations in Global Agenda.
Users are stored in LDAP which allow other apps to authenticate with the same credentials. Some examples we implemented are Redmine, Openproject, Owncloud, Pydio, RocketChat. The global agenda can be used by various types of VoIP phones, even multifunction printers
