When requesting a direct TELEX connection to an Inmarsat-B terminal, which command must be issued by the GMDSS operator?

The command for requesting a direct TELEX connection to an Inmarsat-B terminal requires specifying the ocean area code and the TELEX number correctly. The appropriate command format begins with "DIRTLX," followed by a single digit, which signifies the type of connection being established; in this case, the '0' is the correct prefix for initiating a direct TELEX.

Following this, the operator must include the ocean area code, which identifies the geographic region associated with the TELEX number being dialed. This ensures that the communication is properly routed through the satellite system. Lastly, the TELEX number itself must be entered, along with a plus sign (+) to indicate the completion of the command.

This combination of elements is essential because it allows the satellite communication system to understand exactly what type of connection is being requested and where to direct the call, enabling successful contact with the intended destination. The use of "0" instead of "00" is standard in this context, as "00" is not a recognized command for a direct TELEX request in the GMDSS system. Therefore, the command you provided is the correct format for making this request.