According to the Teledyne Q-flex modem manual, the 5 status LED lights have the following significance:
Rx fault or Rx disabled
Tx fault or Tx disabled
It may seem a bit misleading when the Tx traffic light is green. That really just indicates that the transmit side of the modem is configured and not in a fault condition. It is the Tx Carrier light that actually indicates if the carrier is being transmitted. If the Tx Carrier light is dark, this is usually an indication of the modem either being configured to have transmit set to "Off" or it is set to "Rx Enabled" but the modem does not have a receive lock and therefore is not transmitting.