This read-only counter tracks the total number of ATM cells the port has transmitted outward, in the egress direction, toward the attached customer equipment. An administrator uses it alongside egrRcvCells (cells received from the network side) to gauge how much egress traffic successfully made it out the port versus how much was discarded by queue-full or alarm conditions. A gap between egrRcvCells and egrXmtCells that grows over time points to discards happening somewhere in the egress path on that port.