What must be included in the sign-off line of an AM message?

The sign-off line of an AM (Administrative Message) must include the sending agency and the name of the operator. This is crucial for maintaining clear communication and accountability within the NCIC (National Crime Information Center) system. By listing both the agency and the operator's name, it provides a definitive link back to who sent the message, which is important for verification and response purposes. This practice helps ensure that there is a clear chain of information and responsibility, an essential part of maintaining the integrity of the communications within law enforcement.

In contrast, the other options provide information that is not typically required in the sign-off line. For example, including only a phone number or contact information does not serve the same purpose of accountability. The operator's ID and message timestamp, while important for tracking and record-keeping purposes, are also not mandatory components of the sign-off. Similarly, an operator's badge number is unnecessary for identifying the sender in the context of an AM message.