Appendix C – AT Commands

Standard AT Commands

Most modems use the standard AT commands, as shown in the following tables. Consult the manual for your modem to set what AT commands it supports.

Note that the trailing "n" in many commands indicates a number.

The allowable numbers, and their effect, are listed below the command.

Command

Description

<any key>

Terminate current connection attempt

 

 

 

+++

 

Escape sequence code, entered in data state, wait for modem to return to

 

 

command state

 

 

 

ATA

Force answer mode on-line

 

 

 

ATBn

Handshake operation

 

 

 

 

B0

Select ITU-T V.22 for 1200 bps communication

 

 

 

 

B1

Select Bell 212A for 1200 bps communication

 

 

 

ATD

Dial number and options that follow

 

 

 

 

P

Pulse dial

 

 

 

 

T

Tone dial

 

 

 

 

,

Pause for a specified time

 

 

 

 

;

Return to command state after dialing

 

 

 

 

!

Hook flash, call transfer

 

 

 

 

W

Wait for second dial tone

 

 

 

 

@

Wait for 5-second silence before proceeding, otherwise return O ANSWER"

 

 

 

 

R

Reverse Dial (Originate a call in answer mode)

 

 

 

ATDL

Dial last number

 

 

ATDSn

Dial number stored in NVRAM at position n. (n=0..9)

 

 

ATEn

Command mode local echo of keyboard commands

 

 

 

 

E0

Echo off

 

 

 

 

E1

Echo on

 

 

 

ATHn

On/Off hook control

 

 

 

 

H

Hang up modem

 

 

 

 

H0

Hang up (on hook), same as ATH

 

 

 

 

H1

Get off hook

 

 

 

ATIn

Display inquired information

 

 

 

 

I0

Display product code

 

 

 

 

I1

Display product information and ROM checksum

 

 

 

 

I2

Link status report

 

 

 

93

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Milan Technology MIL-W1311, MIL-W0311 manual Standard AT Commands, Command Description