Specifications

AT Command Set for L55 Platform 2003-11-21

2.2 The AT command set

GSM mobile telephones and modems can be operated via Remote Control using a serial interface

(data cable or infrared connection). Remote control is implemented by means of AT+C commands

according to the ETSI GSM 07.07 [1] and GSM 07.05 [4] specifications, as well as several

manufacturer-specific AT commands. These commands are described in more detail in section 2.2.2.

A command entered at the user port generally begins with an ‘AT’ command prefix. The remainder of

the line is interpreted as a sequence of the commands described below. The commands are not case-

sensitive. More than one command may be given on a single line, with the semicolon serving as the

delimiter between commands.

The “ITU-T Draft new Recommendation V.25ter” specification [5] applies to the sequence of the

interface commands. According to this guideline, commands should begin with the character string

”AT” and end with ”<CR>” (= 0x0D). The input of a command is acknowledged by the display of ”OK”

or ”ERROR”.

A command currently in process is interrupted by each additional character entered. This

means that you should not enter the next command until you have received the acknowledgment;

otherwise the current command is interrupted.

The commands supported are listed in the tables provided in sections 2.2.1, and 2.3.1 through

2.3.9.15.

2.2.1 Hayes Standard commands

The Hayes standard commands correspond to the commands of AT Hayes compatible modems.

All commands in Table 2-7 expect a numeric argument; if this argument is omitted, the default of 0 is

assumed.

The ATD command is a special command in that all characters specified in the same line (or up to a

semicolon) are considered part of the number to dial.

Command Function

AT... Prefix for all commands

ATA Accept call (V.25ter, according to [5])

ATB[n]

This modem command is used to set the bearer service for data connections

(cf. AT+CBST).

<n> can take one of the following values:

7 2400bps, asynchronous, V.22bis

11 4800bps, asynchronous, V.32

13 9600bps, asynchronous, 32

15 14400bps, asynchronous, V.34

25 2400bps, asynchronous, V.110 ISDN

27 4800bps, asynchronous, V.110 ISDN

29 9600bps, asynchronous, V.110 ISDN

31 14400bps, asynchronous, V.110 ISDN