Which message should be sent after stating the type of coordination in interphone communications?

After stating the type of coordination in interphone communications, the appropriate next step is to send a response to the message. This is important as it confirms receipt and understanding of the information provided, ensuring that both controllers are on the same page regarding the coordination details. A response helps maintain clear communication and accountability between the parties involved, which is crucial for safety in air traffic management.

While other elements, such as expected arrival times or operating initials, could be relevant in different contexts, they do not directly follow this particular phase of communication. Identification of the sending controller may be necessary in some situations, but the core purpose here is to respond specifically to the coordination that has taken place. Therefore, providing a response ensures an effective flow of information and collaboration in air traffic control operations.