having data communication difficulties, such as periodic
character loss, random errors, or constant format errors,
use the loopback tests associated with the &T command.
With these tests you can usually isolate the fault in your
system by using the process of elimination. If problems
continue to occur, contact your service representative.

If you would like to download the latest 3821Plus

firmware from the Automatic Firmware Download
Center, see the instructions at the end of this chapter. If
you would like to copy the software in your modem to a
remote 3821Plus modem, see the &&P1 command in

Chapter 4

Table C-1

Modem Health

Symptom

Action

Modem did not pass
power-up self-test

Contact the Customer Assistance Center (1-800-237-0016).

LEDs do not light

Verify that the modem card is fully seated in its slot.

Verify that the power supply for the 3000 Series Carrier is properly installed and is receiving
power.

A problem is suspected
after the power-up self-test

Perform a self-test using the AT&T9 command.

Perform a local analog loopback with a Pattern test. If the modem consistently registers
errors contact the Customer Assistance Center

errors, contact the Customer Assistance Center.

If the modem passes the above tests and a problem still exists, then the problem is likely
not with your modem.