Receive Alarm — yellow LED on indicates a problem with the digital transmission being received. This halfduplex link is unusable. • Receive Error — yellow LED indicates a minor error as a result of degraded digital transmission. Possible causes are an ohmic connection, water ingress, or too long a loop. • Transmit Alarm — red LED on indicates an inability to transmit. Alarm indication signal (AIS) is being transmitted to the terminating switch. This half-duplex link in unusable. • Transmit Error — yellow LED on indicates a remote alarm indication (RAI) carrier failure alarm (CFA) is being sent to the terminating switch. If the Transmit Alarm is not on, this indicates a far-end or cable problem. • In service — a flashing green LED indicates that the T1 or PRI trunks are out of service because of a running loopback test, or because the DTI is being initialized. • Loopback test — red LED on while a continuity loopback test is running. • All LEDs flashing continuously — the DTI is being initialized. 3. Run a Maintenance session and any loopback tests as appropriate. 4. Check the pinout of the cable that connects the DTI to the termination point from the T1 or PRI service provider or the external channel service unit, and check that the cable is properly connected. 5. Check with your T1 or PRI service provider to see if through-fed repeaters are used on the T1 or PRI span. The DTI does not provide the DC conne