How to Configure the Gatekeeper Service in ISA Server to Allow Inbound Netmeeting Calls

This article describes how to configure the H.323 Gatekeeper service in Internet Security and Acceleration (ISA) Server to allow external Netmeeting client computers to call internal clients.

Gatekeeper is an additional service that is packaged with ISA Server that is used with H.323 programs. You can also configure the Gatekeeper service to allow inbound Netmeeting calls. To do so, configure the H.323 Application filter to use the gatekeeper's Internet protocol (IP) address (usually the internal IP address of the ISA Server computer). If you leave the IP address blank on Multicast-enabled networks, the gateway (Application filter) uses Multicast to contact all internal gatekeepers on your network. However, for testing purposes, it is better to specify an IP address.

To configure the H.323 Application filter to use the gatekeeper's IP address:

1. Start the ISA Server Management console, and then click Extensions.
2. Click Application Filters.
3. Double-click the H.323 filter, and then click the Call Control tab.
4. Click to select the Use this Gatekeeper check box.
5. Type the internal IP address of the ISA Server computer.

Next, make sure that there is a protocol rule that allows at least the H.323 protocol:

1. On the Access Policy menu, click Protocol Rules.
2. Add a new rule for the H.323 protocol.
3. Name the rule "H.323", leave it set to Allow, and then click Next.
4. In the Apply this rule to box, click Selected Protocols.
5. Click H.323 in the list of protocols, and then click Next.
6. Accept all the default settings on the next two pages, and then click Finish.

Next, configure the internal Netmeeting client:

1. On the internal Netmeeting client, on the Tools menu, click Options, and then click Advanced Calling.
2. Set the client to use a gatekeeper, and to use the internal IP address of the ISA Server computer.
3. Register the client with a phone number. Make sure you do not use dashes in the number.
   
   This number does not have to be an actual phone number; it is used only for routing the incoming call to the user. This number can be any unique string of numbers. You can enter the user's e-mail address in the Account name box.

Next, configure the external Netmeeting client:

1. On the external Netmeeting client, on the Tools menu, click Options, click Advanced Calling, and then set the client to use a gateway.
2. Enter the external IP address of the ISA Server computer for the gateway.

When the external client places a call, it places a call to the internal clients phone number. When Netmeeting places a call to a phone number, it checks to see if the computer is configured to use a gateway; if it is, Netmeeting routes the call to that gateway.

If you want to configure internal clients to call external clients, you can only make outbound calls to remote users on the Internet (not users who are behind another gateway or gatekeeper) if you use the IP address or the fully qualified domain name (FQDN) of the external client.

For additional information about how to configure internal clients to call external clients, click the article number below to view the article in the Microsoft Knowledge Base: