[This is pre-release documentation and subject to change in future releases. This topic's current status is: Milestone-Ready]

Topic Last Modified: 2010-07-14

Much of the communication in your organization probably involves people outside your firewall: employees who are temporarily or permanently offsite, employees of customer or partner organizations, people who use public instant messaging (IM) services, and potential customers or partners whom you invite to meetings and presentations. Each of these users is a type of external user.

With Microsoft Communications Server 2010, users in your organization can use IM and presence to communicate with external users, and they can participate in A/V conferencing and Web conferencing with your offsite employees and other types of external users. You can also support external access from mobile devices and over Enterprise Voice. External users can sign in to Communications Server without logging on to your intranet, so they do not have to have an internal account in your organization. This can facilitate ease of use and performance for external users.

In order to support communications across your organization’s firewall, you deploy Communications Server Edge Server, in your perimeter network (also known as screened subnet or DMZ). The Edge Server controls how users outside the firewall can connect to your internal Communications Server deployment. It also controls communications with external users that originate within the firewall.

Depending on your requirements, you can deploy one or more Edge Servers in one or more locations. This section describes external user access in Communications Server, and it explains how to plan your edge topology.

Although you need an Edge Server to support Enterprise Voice and Communicator mobile external user access, this section focuses on support for IM, presence, A/V conferencing, and Web conferencing. For details about support for Enterprise Voice, see Enterprise Voice.

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