AT commands are used to communicated to modem and establish tele communication for voice, data and network connections.
From terminal, AT commands need to be ran for old and legacy modems.
AT ---> to check modem connection
ATA ---> command answers an incoming voice call.
+++ - Switches the modem from data to command state; this command is not proceeded by AT.
A - Instructs the modem to attempt to answer a call.
A/ - Re-executes the last modem executed command; this is not proceeded by AT.
Bn - Sets the operation standard 0=CCITT, 1=Bell.
Cn - Turns the modem transmit carrier signal on and off 0=turn off the modem transmit carrier signal during normal operation; 1=Turn on modem transmit carrier signal during normal operation.
Dn - Dials the number, n; 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 four stored telephone numbers; : - Return to command mode after dialing; ! - Go on hook for 1/2 second.
En - Turns the command echo feature on/off so that your commands' either are displayed or are not displayed on the screen 0=off, 1=on.
Hn - Causes the modem to hang up or pick up when in data mode 0=hang up, 1=pick up.
In - Identifies the modem code and the status of the ROM 0=display 3-digit product ID code (preset to 248); 1=display checksum; 2=display checksum and display OK or ERROR.
Ln Sets the internal speaker volume 0,1=lowest, 2=medium, 3=highest.
Mn - Determines when the speaker is on and off; 0=always off; 1=on during call and off when receiving data carrier; 2=always on; 3=off when receiving carrier and during dialing but not when answering.
On - Switches the modem from the command state to the online state; 0=returns the modem to the online state when a connection is still open, 1=returns the modem to the online state and initiates a V.22 bis retain sequence.
Qn - Displays or suppresses (quiets) result codes 0=displays codes (default), 1=suppresses codes
Sr? - Read and display register r
Sr=n - Set register r to value n
Vn - Displays result codes in short form (numbers) or long form (test); 0=Send numeric responses; 1=send word responses.
Xn - Determines result codes that displays the following modem operations; 0=Basic response set, blind dialing; 1=Extended response set, blind dialing; 2=Extended response set, dial tone detection; 3=Extended response set, blind dialing, and busy signal detection; 4=Extended response set, dial tone, and busy signal detection.
Yn - Enables or disables the long space disconnect 0=disable, 1=enable.
Zn - Resets the modem and recalls a user profile; 0=recall user profile 0; 1=recall user profile
For more info:
https://wiktel.com/standards/modemcmd.htm
From terminal, AT commands need to be ran for old and legacy modems.
AT ---> to check modem connection
ATA ---> command answers an incoming voice call.
General at commands
AT - 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 not proceeded by AT.
A - Instructs the modem to attempt to answer a call.
A/ - Re-executes the last modem executed command; this is not proceeded by AT.
Bn - Sets the operation standard 0=CCITT, 1=Bell.
Cn - Turns the modem transmit carrier signal on and off 0=turn off the modem transmit carrier signal during normal operation; 1=Turn on modem transmit carrier signal during normal operation.
Dn - Dials the number, n; 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 four stored telephone numbers; : - Return to command mode after dialing; ! - Go on hook for 1/2 second.
En - Turns the command echo feature on/off so that your commands' either are displayed or are not displayed on the screen 0=off, 1=on.
Hn - Causes the modem to hang up or pick up when in data mode 0=hang up, 1=pick up.
In - Identifies the modem code and the status of the ROM 0=display 3-digit product ID code (preset to 248); 1=display checksum; 2=display checksum and display OK or ERROR.
Ln Sets the internal speaker volume 0,1=lowest, 2=medium, 3=highest.
Mn - Determines when the speaker is on and off; 0=always off; 1=on during call and off when receiving data carrier; 2=always on; 3=off when receiving carrier and during dialing but not when answering.
On - Switches the modem from the command state to the online state; 0=returns the modem to the online state when a connection is still open, 1=returns the modem to the online state and initiates a V.22 bis retain sequence.
Qn - Displays or suppresses (quiets) result codes 0=displays codes (default), 1=suppresses codes
Sr? - Read and display register r
Sr=n - Set register r to value n
Vn - Displays result codes in short form (numbers) or long form (test); 0=Send numeric responses; 1=send word responses.
Xn - Determines result codes that displays the following modem operations; 0=Basic response set, blind dialing; 1=Extended response set, blind dialing; 2=Extended response set, dial tone detection; 3=Extended response set, blind dialing, and busy signal detection; 4=Extended response set, dial tone, and busy signal detection.
Yn - Enables or disables the long space disconnect 0=disable, 1=enable.
Zn - Resets the modem and recalls a user profile; 0=recall user profile 0; 1=recall user profile
For more info:
https://wiktel.com/standards/modemcmd.htm
