Introduction

The Mediation Server is an additional role in the Office Communications Server (OCS) 2007 deployment that allows connectivity to legacy private branch exchange (PBX) systems as well as Public Switched Telephone Network (PSTN). The Mediation Server provides media translation and signaling between a media gateway such as the Audiocodes MP-114 in the sample configuration in this chapter and your Enterprise Voice infrastructure. The Mediation Server is deployed inside your network, behind the firewall. The Mediation Server requires two network interface cards (NIC) because one listens on one NIC secured with mutual Transport Layer Security (TLS) that is connected to your OCS environment and a second NIC that is connected to your gateway over an unsecured connection. Both NICs require a separate IP (Internet Protocol) address. Because traffic from the Mediation Server to the gateway is unsecured, you may want to consider a VLAN or a separate network that provides more security on the unsecured connection.

The Mediation Server s main functions are to translate SIP over the Transmission Control Protocol (TCP) on the gateway side, and over mutual TLS on the Enterprise Voice side. It also encrypts and decrypts the Secure Real-time Transport Protocol (SRTP) on the Communications Server side, translates media streams between the media gateway and the Communications Server, connects clients from outside the network to the internal Interactive Connectivity Establishment components which enable media traversal firewalls, and acts as a connector for calls from remote workers on the Enterprise Voice client.

OCS supports three different gateways: the...