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MultiModemISDN User Guide
sending terminal adapter, then the packet size can be greater than 1024, and Zmodem transfers the
data without
bad packet
errors.
Note: The MTA128ST-USB is manufactured in two builds. To determine the build of your terminal adapter
(TA), issue the ATI2 command in a terminal window. If the TA responds to the command with MTA128ST-
USB, then it supports V.110. If your TA resonds to the ATI2 command with MTA128ST-USB-RC, V.110
support is not available.
The MTA128ST-USB won’t accept V.120 calls from a 3Com Impact IQ terminal adapter.
The Impact IQ displays a connected status, but the MTA128ST-USB does not.
The MTA128ST-USB is looking for a SABME command from the Impact IQ to finish establishing the
V.120 connection. However, the Impact IQ won’t send a SABME until it has data to send. Have the
Impact IQ send a character by pressing any key (such as the space bar) on the terminal attached to
the Impact IQ. The MTA128ST-USB responds with a CONNECT message and displays the key you
pressed (e.g., a space).
MTA128ST-USB receives garbage characters when connected to a 3Com Impact IQ
terminal adapter
Most likely, the Impact IQ has compression turned on. The compression used by the Impact IQ is
incompatible with the compression used by the MTA128ST-USB. Disconnect the data connection and
give the Impact IQ the command AT%CO and then establish the data connection again. The garbage
characters should disappear.
MTA128ST-USB receives garbage characters after receiving several good characters
when connected to a 3Com Sonix adapter
Most likely, the Sonix has compression turned on. The compression used by the Sonix is
incompatible with the compression used by the MTA128ST-USB. Disconnect the data connection and
give the Sonix the command AT”HO (that’s a double quote) and then establish the data connection
again. The garbage characters should disappear.
Each time a 3Com Sonix terminal adapter originates a V.120 call, the MTA128ST-USB
answers the call as a V.110 call*
The Sonix sends V.110 information in the SETUP message to the network. Since the MT A128ST-
USB’s default is with Auto Protocol Detection enabled (ATS52=1), it looks at SETUP information from
the Sonix and determines erroneously that it is a V.110 call. Disable Auto Protocol Detection in the
MTA128ST-USB with the command A TS52=0 and try the connection again.
Note: The MTA128ST-USB is manufactured in two builds. To determine the build of your terminal adapter
(TA), issue the ATI2 command in a terminal window. If the TA responds to the command with MTA128ST-
USB, then it supports V.110. If your TA resonds to the ATI2 command with MTA128ST-USB-RC, V.110
support is not available. If you are using the MTA128ST-USB-RC, the TA will disconnect after several
seconds, rather than answer the call as V.110.
MTA128ST-USB won’t connect to an ELSA terminal adapter with the V.120 data
protocol
Most likely, the ELSA terminal adapter has compression turned on. The compression used by the
ELSA terminal adapter is incompatible with compression used by the MTA128ST-USB. Give the ELSA
the command AT%CO to disable compression and try again.