What type of packet frame is used to transmit APRS beacon data?

APRS operates primarily in a connectionless mode to broadcast data efficiently to anyone listening, rather than establishing a dedicated point-to-point link between two specific stations. In the AX.25 protocol, these broadcast packets are sent as "Unnumbered Information" (UI) frames. UI frames do not require a connection to be established (which would use a "Connect" frame) or an acknowledgment to be sent back by a receiving station (an "Acknowledgement" frame). This "fire and forget" mechanism allows multiple stations to share a single frequency without overwhelming the channel with connection overhead and handshaking.