Aviation protocols are extremely backwards compatible and low-tech compatible. You need to be able to read, write, hear, and speak the identifier. (And receive

Aviation protocols are extremely backwards compatible and low-tech compatible. You need to be able to read, write, hear, and speak the identifier. (And receive/transmit in morse code) Would it be okay to have an "area code prefix" in the identifier? Plausible (but practically speaking too late for that)