Which aspect of 3CX is crucial for connecting to the public telephone network?

Connecting to the public telephone network is primarily accomplished through the use of trunks in 3CX. Trunks serve as the virtual lines that facilitate the communication between the 3CX system and the outside world, specifically allowing calls to be made and received from the Public Switched Telephone Network (PSTN). Without trunks, the system would be unable to interact with external phone systems, thus inhibiting the ability to place or receive standard phone calls from external numbers.

Trunks can be implemented in various forms, such as SIP trunks or PSTN gateways, which bridge the connection between the VoIP network and traditional phone lines. They carry the calls, allowing for the characteristics and benefits of VoIP, like cost savings and scalability, to be utilized. While conferencing capabilities, voicemail systems, and web-based management are important features of 3CX, they do not directly contribute to connecting the system with the public telephone network, making trunks the essential component for this purpose.