3Com 3C882 manual Monitoring LEDs, Monitoring the Test LED, Monitoring the D Channel LED

Monitoring LEDs 7-2

■Verify that the ISDN cable is properly connected to the 3C882 ISDN modem and the ISDN wall jack.

The 3C882 ISDN modem will not operate if connected to an analog telephone wall jack. Make sure that the 3C882 ISDN modem is connected directly into the ISDN wall outlet without connection to any intermediate telephone equipment (an NT1 device is not required with the 3C882 ISDN modem).

Monitoring LEDs

If you are experiencing operational inconsistencies, monitor the TEST, D channel, and B channel LEDs to isolate problems.

Monitoring the TEST LED

Press the Reset button and observe the TEST LED. During power-up self-test, the TEST LED flashes.

■If the LED goes out after the test has been completed, the test has been successful.

■If the TEST LED flashes and remains on for more than a few minutes, there is an internal failure. Notify your reseller that the 3C882 ISDN modem has failed the self-test, and order a replacement.

Monitoring the D Channel LED

Observe the D channel LED. If you are connected to a live digital ISDN line, the D channel LED remains lit for up to a few minutes after the self-test and then begins to flash.

When the D channel LED flashes, it indicates that the ISDN signal is present and it is attempting to synchronize with the telephone company.

When the D channel LED goes out, it indicates that a valid communication channel has been established and you can place calls. If the D channel LED does not go out, refer to the “Evaluating Symptoms and Solutions” section.