When configuring the SBC, which of the following is NOT a required piece of information?

In the context of configuring the Session Border Controller (SBC) for 3CX, it's essential to provide specific details for successful communication with the 3CX PBX. Among the options given, the external IP address of the 3CX PBX is not a required piece of information during the SBC configuration.

When setting up the SBC, you typically need to input the SIP port and the Tunnel Port, as these are crucial for establishing SIP signaling and audio/video media streams. The Tunnel password is also necessary for secure communication, as it authenticates the SBC to the PBX and enables encrypted tunnels for media streams.

In contrast, while the external IP address can assist in identifying the PBX, it is not essential for the SBC configuration process itself. The SBC is designed to work within a network, typically where it already understands its environment and doesn't need the external IP to function effectively. Thus, understanding the operational parameters of the SBC clarifies why the external IP address does not need to be explicitly configured.