Applies to: Exchange Server 2007 SP3, Exchange Server 2007 SP2, Exchange Server 2007 SP1, Exchange Server 2007
Topic Last Modified: 2008-03-20

You must configure the IP gateway devices correctly when you are deploying Microsoft Exchange Server 2007 Unified Messaging for your organization. This topic discusses how to configure the interface of the IP gateways to communicate with the computer that is running Exchange 2007 that has the Unified Messaging server role installed.

Important:
When performing administrative tasks on the IP gateway by using a Web browser, the HTTP requests that are sent over the network when configuring an IP gateway device are not encrypted. To increase the level of security for the IP gateways on your network, use Internet Protocol security (IPsec) or Secure Sockets Layer (SSL) to help protect the administrative credentials and data that is transmitted over the network. We also recommend that you use a strong authentication mechanism and complex administrative passwords to protect the administrative credentials for the device.

IP Gateway Interface

There are several types of ports or interfaces that you must configure to enable communication between a Private Branch eXchange (PBX), IP gateway, and Unified Messaging servers on your network. When you configure an IP gateway, you must consider whether the IP gateway device is analog, digital, or analog and digital. If the IP gateway interface that connects to a PBX is analog, you must correctly configure the appropriate settings to enable the IP gateway to communicate with your Unified Messaging servers on your network. For your Unified Messaging servers to communicate with the IP gateways on your network, you must configure the interfaces to communicate with your PBXs, and you must configure the Local Area Network (LAN) connection or network interface for the device.

The following is a list of suggested resources that contain information that can help you correctly configure your IP gateway interfaces and the network interface:

  • IP gateway, IP PBX, and PBX documentation   See Telephony Advisor for Exchange Server 2007 for configuration files and setup information when configuring your IP gateways, IP PBXs and PBXs.

  • Configuring an AudioCodes-based IP gateway   You can obtain the latest support and configuration information at the Microsoft UM Specialist Resource Page to help you configure AudioCodes-based IP gateways for use with Exchange Server 2007 Unified Messaging.

  • Configuring a Dialogic-based IP gateway   You can obtain the latest support and configuration information for Dialogic-based IP gateways at the Dialogic Technical Documentation Web site.

    Note:
    The third-party Web site information in this topic is provided to help you find the technical information you need. The URLs are subject to change without notice.

We also recommend that all customers who plan to deploy Exchange 2007 Unified Messaging obtain the assistance of a Unified Messaging specialist. A Unified Messaging specialist helps make sure that there is a smooth transition to Exchange 2007 Unified Messaging from a legacy voice mail system. Performing a new deployment or upgrading a legacy voice mail system requires significant knowledge about PBXs and Exchange 2007 Unified Messaging. For more information about how to contact a Unified Messaging specialist, see the Microsoft Exchange Server 2007 Unified Messaging (UM) Specialists Web site.

After you configure the IP gateway IP interface, you must create and configure a UM IP gateway. For more information about how to create a UM IP gateway, see How to Create a New Unified Messaging IP Gateway.

After you install the IP gateway, you must create an UM IP gateway object to represent the IP gateway. After you have created a UM IP gateway object, the Unified Messaging server associated with the UM IP gateway will send a SIP OPTIONS request to the IP gateway to ensure that the IP gateway is responsive. If the IP gateway does not respond to the SIP OPTIONS request from the Unified Messaging server, the Unified Messaging server will log an event with ID 1088 stating that the request failed. To resolve this issue, make sure that the IP is available and online and that the Unified Messaging configuration is correct.

A Unified Messaging server will communicate only with IP gateways or IP PBXs that are listed as a trusted Session Initiation Protocol (SIP) peer. An event with ID 1175 will be logged when multiple DNS hosts share the same IP address. This event may occur if you have configured you DNS zones with a fully qualified domain names (FQDN) for the IP gateways on your network. Unified Messaging protects against unauthorized requests by retrieving the internal URL of the Unified Messaging Web Services Virtual Directory that is located on the server that has the Client Access role installed and then uses the URL to build the list of FQDNs for the trusted SIP peers. When two FQDNs are resolved to the same IP address this event will be logged.

Note:
You must restart the Microsoft Exchange Unified Messaging service if an IP gateway is configured to have a fully qualified domain name (FQDN) and the IP gateway's DNS record is changed after the service has been started. If you do not restart the service, the Unified Messaging server will be unable to locate the IP gateway. This occurs because a Unified Messaging server maintains a cache for all IP gateways in memory, and DNS resolution is performed only when the service is restarted or when an IP gateway's configuration has changed.

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