While using the Red Switch, which feature indicates that you have dialed the correct number at the proper level of security?

The feature that indicates dialing the correct number at the proper level of security while using the Red Switch is the liquid crystal display (LCD). The LCD provides real-time feedback during the dialing process, confirming the successful connection and security status of the call. This visual confirmation is crucial in secure communications to ensure that sensitive information is transmitted only over the authorized and secure lines.

In a high-security environment, the ability to verify the connection through a visual indicator helps prevent miscommunication and ensures that users are aware of the security protocols in place. Other options, such as recorded voice messages or punched media like computer cards and paper tape, do not serve the same immediate function of confirming connectivity and security status in real time.