🔍 Key Concepts

• NBDP/telex call sequence between a ship station and a coast station • The meaning of phasing in a telex/NBDP exchange • The normal order of answerback (WRU/AAB), GA+?, and command codes like DIRTLX+ / OBS+ / AMV+

💭 Think About

• Think through the typical step-by-step flow: call coast station → phasing → what must be confirmed before any message text or commands are sent? • At what point in the exchange are WRU (Who are you?) and AAB (answerback) typically used, and when does GA+? appear in relation to that? • Would a station send detailed commands or full message text before it is sure it is connected to the correct shore station and that the circuit is ready?

✅ Before You Answer

• Verify where phasing sits in the sequence: is it before or after exchanging answerbacks (WRU/AAB)? • Check which event logically must happen immediately after a stable connection is established but before routine text transmission begins. • Confirm the normal order: answerback exchange → GA+? → operational command (DIRTLX+/OBS+/AMV+) → message text. Then match which choice best fits the step just after phasing.