Topic Last Modified: 2011-03-15

The main task of planning for instant messaging (IM) and presence is ensuring that you have enough Front End Servers for your users. In a Front End pool, you should have one Front End Server for every 10,000 users homed in the pool, plus an additional Front End Server to maintain performance when one server is unavailable.

Enabling Communication with External Users

You can greatly increase the benefits of your investment in Microsoft Lync Server 2010 communications software by enabling your users to communicate with external users. External users can include:

  • Remote users   Your organization’s own users, when they are working outside your firewalls and are using their laptops or other Lync Server devices.

  • Federated users   Users from companies you work with who also run Lync Server. To enable your users to easily contact these users, you create federated relationships with these companies.

  • Public users   Users of public IM services, such as IM services provided by the Windows Live network of Internet services, Yahoo!, and AOL, and users of providers and servers that use Extensible Messaging and Presence Protocol (XMPP), such as Google Talk and Jabber.

    Note that a separate license might be required for public IM connectivity with Windows Live, AOL, and Yahoo!

    To use XMPP, you must install the XMPP Gateway. You can download the XMPP Gateway from the Microsoft Download Center at After you install the XMPP Gateway, you need to install the hotfix, which is available for download from

To enable any or all of these scenarios, you need to deploy an Edge Server to help enable secure communications between your Lync Server deployment and external users. Your organization’s remote users and users at federated organizations will be able to see each other’s presence and communicate using IM. For details about enabling communication with external users, see Planning for External User Access in the Planning documentation.

Archiving IM Content

Lync Server provides features you can use if your organization must follow compliance regulations. You can use the Archiving Server to archive the content of IM messages for all users in your organization, or for only certain users you specify. For details, see Planning for Archiving in the Planning documentation.