You can add an internal server to the list of servers authorized to connect to an Edge Server. The list should include the FQDN of the Director (if you have one deployed), and also the FQDN of each Enterprise pool, Standard Edition server, and Mediation Server in your organization.
To add an authorized internal server
On the Edge Server, open Computer Management.
In the console tree, expand Services and Applications, right-click Office Communications Server 2007 R2, and then click Properties.
On the Internaltab, under Servers, click Add Server.
In the Add Office Communications Serverdialog box, in Server name, type the FQDN of the Director, if you have one deployed, and then type the FQDN of each Enterprise pool, Standard Edition server, and Mediation Server in your organization.