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AT Commands
Guidelines for Creating Command Statements
When typing command statements, note the following:
The attention code (AT) may be upper or lower case but not a combina-
tion like aT.
• Press the Enter key to execute a command.
• The command buffer can hold 80 characters.
• Use the backspace or delete key to erase the last character.
Even though the initial AT code must be all upper or lower case, charac-
ters that follow can be any mix of upper and lower case.
Monitor Display
As commands are typed they appear on the monitor so the operator can
verify the input. This is called local character echo. The echo may be
turned on or off using AT commands. Refer to Local Character Echo in
the General Commands section of this chapter for details.
Command Statement Buffer
The modem temporarily stores up to 80 characters in the command
buffer. If this limit is exceeded, the modem does not accept the
command and sends an ERROR message. To correct this condition,
retype the command using 80 characters or less.
The AT characters and punctuation used in telephone numbers do not
take up space in the buffer. Also, blank characters used as spaces to help
increase readability are not counted. For example, the modem reads the
commands
ATD (212) 554-1212
ATD2125551212
ATD 212 555 1212
as having 11 characters each. Commands can be typed in any of these
forms.
5-4
V.3400
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