Basic Hayes modem AT strings


Computer Hope

Showtime developed by Dennis Hayes, the AT commands can specify settings for Hayes compatible legacy modems. If any of these strings happen to cause additional issues with your modem, employ the ATZ command to reset the modem back to default manufacturing plant settings.

Example of generic AT modem strings

AT&F&C1&D2 or AT&FE1Q0V1X4&C1&D2

General at commands


– Gets the modem’s attention. This prefix must be included in all commands unless otherwise noted.


– Switches the modem from data to command state. This command is non proceeded by AT.


– Instructs the modem to endeavour to respond a call.


– Re-executes the last modem executed command. This command is non proceeded by AT.


– Sets the operation standard 0=CCITT, i=Bell.


– Turns the modem transmit carrier point on and off 0=turn off the modem transmit carrier signal during normal operation. 1=Turn on modem transmit carrier point during normal functioning.


– Dials the number,
north. T – Touch-tone dialing, P – Pulse dialing, , – pause 2 seconds, @ – Wait for 5 seconds of silence, R – Dial an originate-only modem, S=n
– Dial one of 4 stored telephone numbers, : – Render to command way after dialing. ! – Go on hook for 1/2 2nd.

Due eastn

– Turns the command echo feature on/off then the commands’ either are displayed or are not displayed on the screen 0=off, 1=on.


– Causes the modem to hang up or option up when in information style 0=hang up, 1=pick upwards.


– Identifies the modem code and the status of the ROM 0=brandish 3-digit product ID code (preset to 248), 1=display checksum, 2=display checksum and display OK or ERROR.


Sets the internal speaker volume 0,1=lowest, 2=medium, iii=highest.


– Determines when the speaker is on and off. 0=always off, one=on during call and off when receiving information carrier, ii=always on, 3=off when receiving carrier and during dialing but not when answering.


– Switches the modem from the command land to the online state. 0=returns the modem to the online country when a connection is nonetheless open, 1=returns the modem to the online state and initiates a Five.22 bis retain sequence.


– Displays or suppresses (quiets) outcome codes 0=displays codes (default), ane=suppresses codes


– Read and display register


– Set register
to value


– Displays event codes in curt form (numbers) or long form (exam). 0=Send numeric responses, one=send word responses.


– Determines consequence codes that displays the following modem operations. 0=Basic response set with bullheaded dialing, 1=Extended response set with bullheaded dialing, 2=Extended response prepare with dial tone detection, three=Extended response set with blind dialing and busy signal detection, 4=Extended response prepare with dial tone and busy point detection.


– Enables or disables the long space disconnect 0=disable, ane=enable.


– Resets the modem and recalls a user profile. 0=recall user profile 0, 1=call up user profile.

Popular:   Computer flat-panel and LCD buying tips

& commands


– Controls the data carrier detect signal, leaving the DCD interchange circuit on at all times or turning it on only when a data carrier is detected. 0=force DCD betoken active, i=DCD signal indicates true state of remote carrier bespeak.

&Ddue north

– Controls DTR (information last set up) transition. 0=Ignore DTR signal, 1=Return to command mode when afterward losing DTR, two=Hang up, plough off auto answer, and render to command mode afterward losing DTR, iii=Reset after losing DTR.


– Returns the configuration to the factory settings. 0=Fetch default configuration, i=Recollect factory default configuration, 2=Recall Sierra factory default configuration for machine-reliable MNP, iii=Recall Sierra factory default configuration for auto-reliable V.42bis.


– Selects the baby-sit tone (not used on calls in the U.South.). 0=Disable baby-sit tone, ane=set guard tone on answering modem to 550 Hz, two=Prepare guard tone to 1800 Hz.


– Sets operation; 0=Sets asynchronous operation.


– Selects the ratio of the make/break interval that the modem uses for pulse dialing. “brand” refers to off-hook, “pause” refers to on-claw, 0=39/61 for U.South., 1=33/67 for United Kingdom.

&Southwarddue north

– DSR override. 0=Forcefulness DSR indicate active; 1=DSR agile according to the CCITT specification.


– Test and diagnostics. 0=Cease current exam, 1=Start local analog loopback test, 2=Unknown, 3=Outset local digital loopback test, four=Grant remote request for remote digital loopback exam, 5=Deny remote request for remote digital loopback test, half-dozen=Kickoff remote digital loopback test, 7=Offset remote digital loopback exam with self-exam, 8=Start local analog loopback examination with self-exam.


– Displays the user profiles and stored numbers.


– Stores the current configuration as
Profile 0
Profile 1
0=Contour 0, 1=Profile i.


– Selects the synchronous clock source. 0=Provide synchronous clock on Environmental impact assessment pin xv.


– Selects what user profile will be the default at power-on and reset. 0=Profile 0, 1=Contour 1.


– Stores phone numbers x in location northward (0-3). x=up to 32 characters. For pulse dialing: 0-ix and dial modifiers for touch dialing, 0-nine, dialing modifiers, A-D, #, and *.

Popular:   MS-DOS and Windows command line bootsect command

MNP commands


Selects the maximum MNP block. 0=64-graphic symbol maximum MNP block. 1=128-character maximum MNP block, 2=192-character maximum MNP cake, three=256-character maximum MNP block.


– Sends a suspension command to a remote modem northward=0-9 in 100 milliseconds.


– Specifies whether data is to be buffered or not. 0=Exercise not buffer information, 1=Buffer data for 3 seconds, until character are received, or until package is detected.


– Dials 1 of four stored telephone numbers.


– Redials the last telephone number dialed.

\1000due north

– Disables or enables DCE flow command.


– Turns off or turns on DTE baud adjustment. 0=Plough off DTE baud charge per unit adjustment.


– Sets the break control.


– Selects connection. 0=Allows standard buffered connection only. i=Allows direct connection only, 2=Allows reliable MNP connection simply, 3=Allows auto-reliable MNP connectedness.


– Stores telephone number.


– Selects menses control. 0=Turns off DTE period control, i=XON/XOFF bi-directional software menstruum control, ii=CTS betoken unidirectional software flow control, 4=XON/XOFF unidirectional flow command (5.42 just)


– Displays modem status.


– Inactivity timer.


– Accepts reliable link from standard link.


– Selects send or do non transport for MNP responses.


– Sets standard XON/XOFF laissez passer through menstruation control. This command works only when a standard buffered connection is established and XON/XOFF catamenia control is being used. 0=Modem acts on XON/XOFF received from the local DTE, only does not pass XON/XOFF to the remote modem. 1=Modem acts on XON/XOFF received from the local DTE and passes XON/XOFF to the remote modem. Using this switch allows the local DTE to XON/XOFF the remote DTE through the established modem link.


– Switches standard link to reliable link.


– Ends the reliable connection and switches to the standard connection.


– Sets the machine-reliable fallback graphic symbol.


– Disables or enables class 5 MNP functioning. 0=Disable class v MNP operation, 1=Enable Class 5 MNP operation.


– Disables or enables auto retain 0=Disable auto retain, 1=Enable auto retain.

Popular:   Computer Hope chat