🔍 Key Concepts

• Maritime Mobile Service Identity (MMSI) structure and what the leading digit(s) mean • How group MMSI, coast station MMSI, and ship station MMSI are formatted differently • The difference between an MMSI and an Inmarsat-C ID, including typical length and use

💭 Think About

• Look at the first one or two digits: what does a leading zero (or multiple zeros) usually indicate in MMSI numbers? • Compare how many digits are in a standard MMSI and whether Inmarsat-C IDs follow the same pattern or a different one. • Think about which type of station (group, coast, ship) would need a special identifying prefix so radios can recognize and handle calls differently.

✅ Before You Answer

• Verify the standard MMSI length and whether 030346239 matches it. • Check which types of MMSI are assigned leading zeros (e.g., 0, 00, or 000) and what each pattern represents. • Confirm whether Inmarsat-C IDs look like MMSIs or use a different format and prefix scheme.