A hardware state machine connected to a processor, the hardware state machine configured to receive operational codes from the processor; a multiplexer connected to the processor, the hardware state machine and a checksum circuit, the multiplexer configured to receive data from the processor; and a transmit circuit connected to the multiplexer, the transmit circuit configured to receive data from the multiplexer for transmission to a far end device, wherein the hardware state machine is further configured to, responsive receiving one or more operational codes from the processor: cause the checksum circuit to alter a checksum value of a first data packet being transmitted by the transmit circuit; and cause the transmit circuit to preempt transmission of the first data packet and begin transmitting a second data packet once the checksum value so altered has been transmitted from the transmit circuit.