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AT Command, S-Registers, and Result Codes
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Result Codes
When the MTA128ST/NT receives an AT command from the computer or terminal, it attempts to execute the
command, then sends a status message to the computer or terminal that reports the result of the command.
The MTA1 28ST/NT provides you with several of these response messages, or result codes, which can be
displayed on your monitor or intercepted and used by your communications software. Using the V
command, you can select whether the result codes are terse (numbers) or verbose (words).
The MTA128ST/NT’s result codes are listed below. Note that the speed of an ISDN channel is always
either 56 Kbps or 64 Kbps. Connect messages indicate the speed of the connection between the
MTA1 28ST/NT and your computer or terminal.
TERSE VERBOSE DEFINITION
0 OK TA executed the command without error
1 CONNECT TA established an ISDN connection
2 RING TA detected a ring caused by incoming call
3 NO CARRIER TA did not detect carrier within time allotted by register
S7
4 ERROR Error in the AT command
5 CONNECT 1200 TA connected at 1200 bps
6 NO DIALTONE TA has a poor connection to ISDN network
7 BUSY TA detected a busy signal
8 CONNECT 300 TA connected at 300 bps
9 CONNECT 600 TA connected at 600 bps
10 CONNECT 2400 TA connected at 2400 bps
11 CONNECT 4800 TA connected at 4800 bps
12 CONNECT 9600 TA connected at 9600 bps
14 CONNECT 19200 TA connected at 19200 bps
17 CONNECT 56000 TA connected at 56000 bps
18 CONNECT 57600 TA connected at 57600 bps
19 CONNECT 64000 TA connected at 64000 bps
28 CONNECT 38400 TA connected at 38400 bps
79 PPPC PROTOCOL TA using Point-to-Point protocol
80 HDLC PROTOCOL TA using raw HDLC mode
83 V.120 PROTOCOL TA using V.120 rate adaption protocol
84 X.75 PROTOCOL TA using X.75 rate adaption protocol
87 CLEAR PROTOCOL
TA using CLEAR (transparent) protocol
Using AT Commands to Operate the MTA128ST/NT
You can configure and operate the MTA1 28ST/NT entirely with AT commands if you like. But remember,
you can issue AT commands only from a terminal or from a computer running a communications program in
terminal mode. This section describes how to use AT commands for basic operations, such as calling,
answering a call, and hanging up.
Modes of Operation
The MTA1 28ST/NT has three modes of operation. They are:
•
Offline Command Mode—MTA1 28ST/NT communicates with the terminal or computer and responds to AT
commands. There is no data communications link with a remote device.
•
Data Mode—MTA128ST/NT enters data mode when it makes a successful data communications link
with a remote device. In data mode, the TA can send and receive data, but it does not respond to AT
commands. Instead it treats them as data and transmits them to the remote device.
•
Online Command Mode—MTA128ST/NT responds to AT commands while maintaining a data
communications link; however, transmission of data is suspended. To enter online command mode from
data mode, type the escape sequence +++AT<cr>. To return to data mode from online command
mode, type ATO<cr>.