> 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 1.5: | Types of AT commands and responses

> AT command type | Syntax | Function
> 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.
> Exec(ution) command | AT+CXXX | The execution command reads non-variable parameters determined by internal processes in the GSM engine.