After completing the setup of an Edge Server or Edge pool, you must enable the types of external user access that you want to support and configure support for the external users that your organization wants to support. You create and configure any site and user policies that you want to use to limit external user access to specific sites or users.
To configure a policy to support access by users of federated domains
- From a user account that is a member of the RTCUniversalServerAdmins group (or has equivalent user rights), or is assigned to the CsAdministrator role, log on to any computer in your internal deployment.
- Open a browser window, and then enter the Admin URL to open the Lync Server Control Panel. For details about the different methods you can use to start Lync Server Control Panel, see Open Lync Server Administrative Tools.
- In the left navigation bar, click External User Access, and then click External Access Policy.
- On the External Access Policy, Edit Lync Server User, select the user policy that you want to apply.
Turns out that none of this will actually get me what I want.. (see my TechNet question} the real term for it is:
An ethical wall is a zone of non-communication between distinct departments of a business or organization. This zone is established to help prevent conflicts of interest that might result in the inappropriate release of sensitive information .
An ethical wall typically spans multiple methods of communication, such as telephone, e-mail, postal mail, and direct person-to-person communication. To make sure that no communication occurs between those regulated by an ethical wall, some organizations go so far as to put whole departments on separate floors or buildings and to require that employees use separate entrances.
One example of where an ethical wall could be used is in an investment organization where brokers aren’t allowed to talk to market researchers who may have information that isn’t available to the general public. Because market researchers may have confidential information that might influence a broker, regulatory requirements frequently state that those two groups must be prevented from communicating in any way. (source)
There are a bunch of companies out there that sell solutions for ethical walls (no specific endorsement):
… Good luck restricting your communications.