72 Chapter 6 Setting up the private VoIP networkNN40140-500NN40140-500Network securityFirewall configuration for SRG is the same as for the BCM50 and is detailed in the NetworkingConfiguration 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 alsocovered in the Networking Configuration Guide (NN40020-603).VoIP trunking configurationWhen the SRG is operating in normal mode, connectivity to the main office call server is overVoIP 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 74Fallback configurationFor SRG operation, fallback and gatekeeper configuration is common to all VoIP trunks. Fallbackis determined in conjunction with the QoS settings (see To enter the QoS settings for VoIP trunkson page 71).Note: For calls originating from IP Sets, configure the payload size. Access the IP Sets configurationpanel in Element Manager (Configuration > Resources > IP Sets > IP Terminal Global Settings.Change the Payload Size to 20ms.To enable fallback1 Access the IP Trunks configuration panel in Element Manager (Configuration > Resources >Telephony Resources > Modules panel > Module type column) and then select IP Trunks.2 On the Details for Module panel, select the H323 Settings tab or the SIP Settings tab.3 On the Telephony Settings subpanel, locate the Fallback to circuit-switched field and use thelist to:a select Enabled-All if you want calls to be able to fallback to PSTN trunks if connectivityto the main office is lost.b select Enabled-TDM if you want all TDM calls to be able to fallback to PSTN trunks ifconnectivity to the main office is lost.c select Disabled if fallback is not required.
