You receive a TELEX with the sender's I.D. of 436640927. What type of terminal sent this message to your vessel?

The identification number 436640927 indicates that the message was sent from an Inmarsat-C terminal. Inmarsat-C terminals have a specific format for their identifier codes, which typically consist of a 9-digit numeric string. When you see a number like 436640927, it fits the Inmarsat-C format, meaning that it is indeed transmitted from a satellite terminal operating within the Inmarsat network.

Inmarsat-C systems are widely used for maritime communications, providing essential services including distress alerts, messaging, and email capabilities to vessels at sea, which is crucial for ensuring safety and operational effectiveness.

The other types of terminals referenced do not follow the same identification format as Inmarsat-C. Fleet 77 and Inmarsat-M communications operate under different systems and protocols, which would yield different identification numbers. A Land TELEX terminal would generally not be relevant to maritime communications in the same context and would typically relay messages in a different manner. Thus, recognizing the structure of the identification code allows for the conclusion that the terminal in question is an Inmarsat-C terminal.