Configure LAN/Subscriber-Side Gatekeeper Mode Settings

LAN/Subscriber-Side Gatekeeper Mode

Allows WAN side H.460/H.323 clients to proxy register and provide H.460 traversal methods to the system WAN interface. The system forwards all RAS and Q.931 messages to the LAN gatekeeper for registration and call control. The system maintains an H.323 client list for all WAN side devices that have been registered by the LAN gatekeeper.

Also allows B2B calls to proxy through to the LAN gatekeeper for call processing. Certain LAN gatekeepers can be configured to forward offnet or public IP or ANNEX O (URI-Dialing) WAN-side destination calls for B2B calling.

LAN/Subscriber-side GK address

Enter the IPv4, IPv6, or FQDN address of the LAN gatekeeper that all client messaging is forwarded to for registration and call control.

Send parsed ANNEX O string Outbound

Select the Send parsed ANNEX O string Outbound checkbox to remove the host portion of the destination address.

For example, when the incoming destination address from the LAN is formatted as a H.323 URL 1234@example.com, the outgoing destination address will be parsed and sent as dialedDigits 1234 to the resolved example.com host address.

Send Unmodified Dial String to Gatekeeper

Select the Send Unmodified Dial String to Gatekeeper checkbox to forward all destination address information to the LAN gatekeeper unmodified.

For example, when the incoming destination address to the WAN is 9876@example.com, the system forwards this destination address to the LAN gatekeeper unmodified as 9876@example.com. When this option is not used, the host portion is stripped off and is forwarded to the LAN gatekeeper as destination address 9876.

Note: If the host part of the Annex O address resolves to the LAN gatekeeper device, routing loops can occur. When this option is selected, ensure the gatekeeper receiving the full ANNEX O string is properly configured and capable of receiving the full destination unresolved ANNEX O address. Some older gatekeepers cannot receive this unresolved string and the call will fail.

(Optional) Select the Allow public IP in LCF checkbox to allow public IP addresses to be returned in an LCF. This option should usually not be enabled.

When this option is set, the system does not ALG the address in the Location_Confirm (LCF) to the system WAN IP. This allows the public IP WAN gatekeeper to send call setup directly to the public IP of the LAN gatekeeper.

By allowing public IP addresses to be returned in an LCF, the gatekeeper may be able to do more complex policy decisions.

This field should usually not be enabled; only use when the system has public IPs on both the WAN and LAN interfaces.

Decreases the TTL in the LCF to prevent LCF looping when Allow public IP in LCF is enabled.

Sets the port returned in Admission Confirm (ACF) messages. If no Custom Q.931 port is set, the default port of 1720 is used.

Remote NAT devices can intercept H.323 messages and modify these messages which results in call failure. Changing the TCP call setup port to something other than TCP 1720 can help with call completion in these cases. For example, modifying this field to port 5000 modifies the RCF message to instruct the registered WAN side clients to use this port for call signaling. TCP 1720 will still be a system listening port for B2B calls.

Note: Ensure the alternate port is not being used for other services.

Enter the time in seconds between TCP keep-alive messages. If this value is zero, no keep-alive messages are sent.

If no response is received, the TCP stack assumes the connected endpoint is no longer listening, and ends the connection. This field sends TCP keepalives to clients connected to the systems well known TCP 1720 port.

Default is 0 (disabled); the minimum setting is 120 seconds.

Select a default alias to be added to incoming calls without a destination message in the Q.931 Setup message:

• E.164

• H.323

This alias allows the embedded gatekeeper or a LAN/Subscriber-side gatekeeper to route the call to a default endpoint.

For example, when a B2B call is placed to the system and the user only dialed the IP or FQDN of the WAN interface, the system adds this alias to the H.323 call setup message and forwards it to the LAN gatekeeper for call processing. This alias can be any alias actively registered to the LAN gatekeeper.

You may add a H.323 static client in the H.323 Clients List and configure this client as the default alias. The static H.323 client should be locked to prevent the client entry from being deleted.

A typical configuration scenario is to configure this field with an MCU IVR alias or a default MCU meeting room alias.

Default is E.164, no alias is set.