User's Manual Part 1

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Chapter 3: AT
Commands
AT Commands allow communications software to control and direct the modem.
The term AT is derived from the word ATtention, meaning to get the modem’s
attention. AT Commands are issued by an intelligent device to a modem to
perform a specific function. For example, AT Commands can be used to initiate
a call, answer a call or to simply transmit data.
The ETSI specification created a complete set of commands to interface with the
terminal adapter or modem as well as specifying certain commands from ITU 25.
To make the AT Command interface easier to understand and provide faster
customer integration, a number of the standard AT Commands have been
implemented to substitute some of the more specialized ETSI commands. All
commands relevant to the control and operation of the modem have been
implemented.
This chapter will provide the following information:
• Merlin AT Commands listed by functions
• AT Command explanations, including a description, syntax, parameters,
response and an example. For more information please see “AT
Command Set by Name” on page 53.
• The prefix AT obtains synchronization, identifies the character
parameters, and indicates that a command may be in the following
characters.
• AT Commands are not
case sensitive; use upper or lower case letters in
the command syntax.
The symbol <cr> represents an AT command’s terminating
character, used to send the AT command to the modem. By default,
this terminating character is set to the carriage return character
assigned to the “Enter” key on your keyboard.
Topics Included in this Chapter
AT Command Set by Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
AT Command Set by Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
CME ERROR Codes for GSM 07.07 Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
CMS Error Codes for GSM 07.05 Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143