1.3 Conventions and abbreviations
Throughout the document, the GSM engines are referred to as ME (Mobile Equipment), MS (Mobile
Station), TA (Terminal Adapter), DCE (Data Communication Equipment) or facsimile DCE (FAX modem,
FAX board).
To control your GSM engine you can simply send AT Commands via its serial interface. The controlling
device at the other end of the serial line is referred to as TE (Terminal Equipment), DTE (Data
Terminal Equipment) or plainly “the application” (probably running on an embedded system).
All abbreviations and acronyms used throughout this document are based on the GSM specifications.
For definitions please refer to TR 100 350 V7.0.0 (1999-08), (GSM 01.04, version 7.0.0 release 1998).
1.4 AT command syntax
The "AT" or "at" prefix must be set at the beginning of each command line. To terminate a command
line enter <CR>.
Commands are usually followed by a response that includes “<CR><LF><response><CR><LF>”.
Throughout this document, only the responses are presented, <CR><LF> are omitted intentionally.
Table 1: Types of AT commands and responses
Test command AT+CXXX=? The mobile equipment returns the list of parameters and
value ranges set with the corresponding Write command
or by internal processes.
Read command AT+CXXX? This command returns the currently set value of the parameter
or parameters
Write command AT+CXXX=<...> This command sets user-definable parameter values.
Execution command AT+CXXX The execution command reads non-variable parameters
affected by internal processes in the GSM engine.
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