How to deal with call failure or PCM instability in connecting digital board to optical transceiver?
1) Check if the board has a correct clock setting and if it is grounded properly. 2) Use the PBX to perform a self-loop testing on the board to ensure the good condition of lines. 3) Directly connect the board to the PBX and not through the optical transceiver, to find out if something is wrong with the connection of optical transceiver. 4) See if the impedance of board conforms to that of optical transceiver. 5) Check if the CRC-4 check switch is set properly.
