What phrase is used to call all stations on the radio?

The phrase used to call all stations on the radio is commonly referred to as "Security-security-security." This phrase serves as a general call to all maritime stations, indicating that there is an important message to be communicated. It is often used to convey messages related to the safety of navigation or other important information that all vessels in the vicinity should be aware of.

"Security" is a term that indicates the nature of the message concerning safety, which is crucial in marine communication. This call precedes information that is meant for all ships or stations, essentially alerting them to pay attention to the message that follows.

In contrast, "Mayday" is a distress call used in emergencies where there is immediate danger to life or the vessel. "PAN PAN PAN" signifies urgency but not immediate danger to life or vessel, and "Charlie Quebec" does not specifically relate to a general call but rather pertains to phonetic communication in identifying information. Understanding these distinctions helps in the appropriate use of radio communication protocols in maritime situations.