NIFOG 2.0 - Interoperability Communications Order Model

from https://www.cisa.gov/sites/default/files/publications/NIFOG%20Ver%202.0_508%20version_FINAL_9_23_2021_%28signed%29.pdf
- on page 30 of 192

Interoperability Communications Order Model

Communications Order Model refers to the order of the radio
identification or callsign of the sender and receiver is spoken. The
prevailing model in the U.S. has a common order in how a message is
initiated. Often, this model is referred to a "Hey you, It's me." The
sender states the unit/person called, followed by the sender's unit or
name.

Example: "Dispatch, this is Engine 21." The response is the reverse:
"Engine 21, this is Dispatch, go ahead."

Establishing this order model increases interoperability so that units
are aware which identification/callsign comes first. This model is
used by the amateur radio community, the Department of Defense, the US
Coast Guard, the National Guard, many public safety agencies across
the country, and is endorsed by APCO and SAFECOM.

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zerg90 says - might be nice to add this rule - whoever starts the
conversation says "channel clear" at the end - or something like that