As part of your initial deployment of Office Communications Server 2007 R2, you must deploy the core server and client components for internal IM, presence, and conferencing, as well as additional components required IM and conferencing in your organization.
Although these components can support both internal and external clients, support of external clients, such as remote users, federated partners, and public IM connectivity users also requires deployment of the appropriate perimeter network components. For details, see Planning for External User Access.
Additionally, if you are deploying other optional features and functionality, such as chat rooms, mobile access, archiving, and additional administrative and management support, you will need additional components. For details, see Group Chat, Archiving Support, Planning for Mobile Access, and Administration and Management Tools.