Technical information

May 31, 2008 AT+i Commands Reference Manual 1-1
Chapter 1: Introduction to AT+i Commands
AT+i Commands Overview
AT+i commands are an extension to the basic AT commands set. They are parsed and acted upon
by W24.
Note: The terms 'Command' and 'Parameter' are used throughout this document to refer to AT+i
commands as follows:
• A 'Command' is an AT+i command that executes an operation
• A 'Parameter' is an AT+i command that sets/gets a parameter value in database
W24 in dial-up mode only: When W24 is in COMMAND mode, basic AT commands and raw
data (not prefixed by AT+i) are transparently transferred to the underlying modem DCE (Digital
Communications Equipment), where they are serviced. When transferring data transparently to
the DCE, the hardware flow control signals (CTS, RTS, DTR and DSR) are mirrored across the
W24, unless disabled by the FLW parameter. AT and AT+i commands may be issued
intermittently. During an Internet session, when W24 is online, an AT command can be sent to the
modem using the AT+iMCM command.
The ASCII ISO 646 character set (CCITT T.50 International Alphabet 5, American Standard
Code for Information Interchange) is used for issuing commands and responses.
Only the low-order 7 bits of each character are used for commands or parameters; the high-order
bit is ignored. Upper-case characters are equivalent to lower-case ones.
AT+i Commands Format
An AT+i command line is a string of characters sent from the host to the W24 while it is in
command state. The command line has a prefix, a body, and a terminator. Each command must
begin with the character sequence AT+i and terminated by a carriage return (<CR>). Commands
can be entered either in upper-case or lower-case.
W24 in dial-up-mode only: Commands that do not begin with the AT+i prefix are transferred to
the underlying DCE, where they are parsed and acted upon. DCE responses are transparently
returned to the host.
The AT+i command body is restricted to printable ASCII characters (032-126). The command
terminator is the ASCII <CR> character. The command line interpretation begins upon receipt of
the carriage return character. An exception to this rule are the AT+iEMB, AT+iSSND,
AT+iTBSN and AT+iFSND commands.
When ECHO is enabled, the <CR> character is echoed as a two-character sequence: <CR><LF>
(Carriage Return+Line Feed).