Step 5. Deploy a Mediation Server

Topic Last Modified: 2009-05-06

You can deploy a third-party Basic Media Gateway either before or after you deploy a Mediation Server, but whichever order you choose, these two components must be configured to function as a logical unit. For details about configuring a Mediation Server, see Configuring a Mediation Server.

The settings that you must configure on your Basic Media Gateway are specified in the following list, but for details about how to configure these settings on a given gateway, refer to the manufacturer's product documentation. For details about selecting gateways for Enterprise Voice, see Enterprise Voice Server-Side Components in the Planning and Architecture documentation.

Each gateway must be configured according to the vendor's documentation. Depending on the vendor, there are potentially many attributes that must be set, but the attributes specific to Enterprise Voice are as follows:

• The fully qualified domain name (FQDN) or IP Address of the Mediation Server that is associated with the gateway.

• The listening port (5060) that is used for Transmission Control Protocol (TCP) or Transport Layer Security (TLS) connections to the Mediation Server.

  Important

  The previous settings must match those of corresponding settings for the Mediation Server. If the settings do not match, the connection between the gateway and Mediation Server will fail.

• Session Initiation Protocol (SIP) Transport – specify either TLS (recommended) or TCP.

  Important

  If you specify TLS as the SIP transport to be used by your basic or basic-hybrid media gateway, you must also configure the corresponding Mediation Server for TLS. For details about how to configure a Mediation Server for TLS, see Configuring a Mediation Server.

• If the SIP transport for the link between the gateway and the Mediation Server is set to TLS, the gateway must be configured with a certificate for purposes of authentication during the mutual TLS (MTLS) handshake with the Mediation Server. The certificate on the gateway must be configured as follows:

  • The certificate may be directly signed by the trusted certification authority (CA) configured in the Mediation Server. Alternatively, a certificate chain may have to be traversed to verify the certificate provided by the gateway. The gateway must provide this chain as part of its TLS handshake with the Mediation Server.
  • The CN part of the subject field should be set to the FQDN of the gateway. If the FQDN in the CN part of the subject field does not match the expected and configured FQDN for the gateway, the certificate must also contain a subject alternate name (SAN) that lists the expected and configured FQDN for the gateway.
  • The Mediation Server validates the certificate provided by the gateway by checking that the FQDN on the certificate exactly matches the gateway FQDN configured on the Mediation Server. If the FQDNs do not match, the session is terminated. Additional validation includes checking the signature and expiration date, and making sure that the certificate has not been revoked.

• You must specify the port that each gateway is listening to for incoming SIP connections.

  Note

  Port 5060 is the default destination port used by the Mediation Server.

• If you configure TLS for the SIP transport link between the IP Gateway and the Mediation Server, you must specify whether Secure RTP (SRTP) encryption is:

  • Required: SRTP should be attempted, but do not use encryption if negotiation for SRTP is not successful.
  • Optional: Attempt to negotiate the use of SRTP to secure media packets. If SRTP cannot be negotiated, use Real-time Transport Protocol (RTP).
  • Not used: Send media packets using RTP.

• Each gateway should be configured so that the E.164 numbers routed by Enterprise Voice to the gateway are normalized to a locally dialable format.
• Each gateway should be configured to pass only E.164 numbers to the Mediation Server. Please see each gateway vendor's documentation for specific instructions on how to normalize source phone numbers to E.164.
• Each gateway should be configured to convert the source number (the number presented as caller ID) to a normalized E.164 number. This ensures the caller ID can be matched to a Communicator contact, an Outlook contact, or a member of the corporate directory, thereby enabling Communicator to provide additional information about the caller. This number will also appear in e-mails notifying the user of missed calls and voice mail, allowing the user to click the phone number in order to quickly return a call. If the number has been normalized by the gateway, no further processing is required. If for some reason the number cannot be normalized by the gateway, the normalization rules defined by the location profile will be applied when returning a call. It might be necessary to add normalization rules to a location profile to handle numbers that cannot be normalized by the gateway. Please see each gateway vendor's documentation for specific instructions on how to normalize source phone numbers to E.164.
• If you want the Mediation Server to strip the plus sign (+) prefix from the Request Uniform Resource Identifier (URI), the To URI, and the From URI of E.164 numbers of outgoing calls to the gateway, set the Windows Management Instrumentation (WMI) setting called RemovePlusFromRequestURI to TRUE (the default value is FALSE). For details about this setting, see the "New Configuration Options in Mediation Server" section in Enterprise Voice Server-Side Components in the Planning and Architecture documentation.

For a list of media gateway vendors, see Partners by Capability: Hardware at the Microsoft Web site: https://go.microsoft.com/fwlink/?LinkID=129616.