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MultiModemISDN User Guide
Introduction
This chapter describes basic problems you may run into with your MTA128ST-USB and how to solve
them. Your MTA128ST-USB was thoroughly tested at the factory before it was shipped. If you are
unable to make a successful connection, or if you experience data loss during your connection, check
the following possibilities before calling Technical Support (see Chapter 6).
•None of the LEDs light when the MTA128ST-USB is on.
•The MTA128ST-USB does not respond to commands.
•The MTA128ST-USB dials but cannot make a connection.
•You can place data calls but not voice calls, or vice versa.
•You cannot place two simultaneous data calls.
•The MTA128ST-USB disconnects while online.
•The MTA128ST-USB cannot connect when answering.
•File transfer appears slower than it should be.
•Data is being lost.
•There are garbage characters on the monitor.
None of the LEDs light when the MTA128ST-USB is on
When you turn on the MTA128ST-USB, the LED indicators on the front panel should flash briefly as
the unit runs a self-test. If the LEDs remain off, the unit probably is not receiving power.
•Make sure the MTA128ST-USB’s power switch is on, especially if you normally turn on the unit
by turning on a power strip.
•If the power supply is plugged into a power strip, make sure the power strip is plugged in and
its power switch is on.
•Make sure the power supply module is firmly connected to the MTA128ST-USB and to the
wall outlet or power strip.
•If the power strip is on and the MTA128ST-USB is switched on, try moving the unit’s power
supply to another outlet on the power strip.
•Test that the outlet is live by plugging another electrical device into it.
•The MTA128ST-USB or power supply may be defective. If you have another Multi-Tech
MTA128ST-USB, try swapping units. If the problem goes away, the first unit or power supply
may be defective. Call Tech Support for assistance.
Caution: Do not under any circumstances replace the power supply module with one designed for
another product, as it may damage the MTA128ST-USB and void your warranty.
The MTA128ST-USB does not respond to commands
•Make sure the MTA128ST-USB is plugged in and turned on. (See

None of the LEDs Light

When the MTA128ST-USB Is On.

)
•Try resetting your MTA128ST-USB by turning it off and on.
•Make sure you are issuing the MTA128ST-USB commands from the data communications
software, either automatically, or manually in terminal mode. (You cannot send commands to