This read-only integer, though its source description is blank, is named as the transmit count for this port, implying it tallies outbound packets or frames sent on this specific gateway channel. An admin would use it the way any transmit counter is used operationally: comparing it against the paired recvCount to see if outbound traffic volume for the port looks proportionate to inbound. For example, a port whose xmitCount barely increases while a call is clearly active on it, per portStatus, would suggest a one-way audio problem on the transmit side.