This connection uses pass-through systems as configured by TCP/IP address or host name.
Pass-through systems use modems or VPNs that exist on a designated system to connect to your service provider. For example, an i5/OS operating system can be configured as a pass-through system to allow the HMC to use a modem or VPN connection it is managing.
Note: Do not use a pass-through connection to configure another HMC as a call-home server. To configure another HMC, use the Configure Call-Home Servers step in the Call-Home Wizard.