Nortel Networks SRG50 manual Network security, VoIP trunking configuration, Fallback configuration

72Chapter 6 Setting up the private VoIP network

Network security

Firewall configuration for SRG is the same as for the BCM50 and is detailed in the Networking Configuration Guide (NN40020-603). Firewalls cannot be configured to allow VoIP pass through. Instead, the SRG supports IPsec tunnels to provide VoIP pass through. IPsec tunnels are also covered in the Networking Configuration Guide (NN40020-603).

VoIP trunking configuration

When the SRG is operating in normal mode, connectivity to the main office call server is over VoIP trunks. An SRG can support up to 60 VoIP trunks.

Configuring VoIP trunks has three components:

•Fallback configuration on page 72

•Gatekeeper routing on page 73

•Line pools on page 74

Fallback configuration

For SRG operation, fallback and gatekeeper configuration is common to all VoIP trunks. Fallback is determined in conjunction with the QoS settings (see To enter the QoS settings for VoIP trunks on page 71).

Note: For calls originating from IP Sets, configure the payload size. Access the IP Sets configuration panel in Element Manager (Configuration > Resources > IP Sets > IP Terminal Global Settings. Change the Payload Size to 20ms.

To enable fallback

1Access the IP Trunks configuration panel in Element Manager (Configuration > Resources > Telephony Resources > Modules panel > Module type column) and then select IP Trunks.

2On the Details for Module panel, select the H323 Settings tab or the SIP Settings tab.

3On the Telephony Settings subpanel, locate the Fallback to circuit-switchedfield and use the list to:

a select Enabled-Allif you want calls to be able to fallback to PSTN trunks if connectivity to the main office is lost.

b select Enabled-TDMif you want all TDM calls to be able to fallback to PSTN trunks if connectivity to the main office is lost.

c select Disabled if fallback is not required.

NN40140-500