What action must be performed before adding a PSTN gateway?

Before adding a PSTN gateway in a 3CX system, running the firewall checker is a crucial first step. The firewall checker helps to identify any connectivity issues that may prevent the 3CX system from communicating correctly with external networks, including the PSTN gateway. Properly configured firewalls are essential for ensuring that SIP and RTP traffic can flow without interruption. This step is vital to ensure that any potential issues are resolved before integrating the gateway, which could result in complications or failures in call handling.

While updating firmware, resetting VoIP settings, or checking hardware specifications may be necessary under specific circumstances, the immediate requirement for integrating a PSTN gateway is to confirm that network connectivity is established and secure through the firewall.