Over what system are Enhanced Group Calls transmitted?

Enhanced Group Calls (EGC) are transmitted over the Inmarsat satellite system. This system is designed to provide global satellite communication services, particularly for maritime applications. EGC is specifically utilized to transmit safety-related messages to multiple vessels simultaneously, ensuring timely delivery of important information such as weather updates, navigational warnings, and other safety notices.

The Inmarsat system supports such group communication due to its satellite coverage, which allows for widespread and reliable connectivity across the oceans. EGC messages are sent to registered vessels equipped with appropriate satellite communication equipment, allowing these vessels to receive messages without the need for individual transmissions.

Other systems mentioned, like COSPAS satellites, are primarily focused on search and rescue operations rather than the group call capabilities. HF SITOR shore stations and NAVTEX also serve distinct roles in maritime communication—HF SITOR is commonly used for narrow-band direct printing, and NAVTEX specifically broadcasts maritime safety information, but neither is designed to handle the enhanced group call functionality that Inmarsat provides.