Connect your laptop to the port with correct baud settings and enter a control q or control z and the port should start up again. you can prevent this from happening again by only connecting the transmit and ground to the call accounting box. What has probably happened was the the call recorder may have rebooted/ locked up, etc. Sometimes the software will shut down the port. Using just transmit and ground from the PBX prevents the call recorder from talking back. The only drawback is that there is no buffer then in case of failure.