Which of the following must be programmed into a D-STAR digital transceiver before transmitting?

D-STAR is a digital voice protocol that relies on the user's call sign to route communications over the network. Unlike traditional analog radios where you simply announce your call sign by voice, D-STAR automatically embeds your programmed call sign into the header of every digital data packet you transmit. This digital header is essential for the D-STAR network to authenticate you, track your location across repeaters, and properly route calls specifically directed to you. Options like codec type are inherently baked into the D-STAR protocol's hardware and do not need to be manually configured.