AT commands

Note: Pulse dialing is WiP.

Basic AT commands

• ATA Answer incoming call
• ATB Select Communication Protocol
  • ATB15 set ITU V.21 modem type
  • ATB16 set Bell103 modem type
• ATC Transmit carrier
  • ATC0 disable running TX carrier
  • ATC1 enable running TX carrier
• ATD Call
  • ATDTnnn tone dialing, nnn is the phone number
  • ATDPnnn pulse dialing, nnn is phone number
• ATE Set local command mode echo
  • ATE0 disable local character echo in command mode
  • ATE1 enable local character echo in command mode
• ATF Set local data mode echo
  • ATF0 Half Duplex, modem echoes characters in data mode
  • ATF1 Full Duplex, modem does not echo characters in data mode
• ATH Hook control
  • ATH0 force line on hook (off-line)
  • ATH1 force line off hook (on-line)
• ATI Show info
  • ATI0 device name and speed
  • ATI1 ROM checksum
  • ATI2 tests ROM checksum, then reports it
  • ATI3 firmware revision
  • ATI4 data connection info (modem features)
  • ATI5 regional settings
  • ATI6 long device description
  • ATI7 manufacturer info
• ATL Set speaker volume level
  • ATL0 medium volume, -9dB
  • ATL1 medium volume, -6dB
  • ATL2 medium volume, -3dB
  • ATL3 maximum volume, 0dB
• ATM Speaker control
  • ATM0 speaker always off
  • ATM1 speaker on for TX
  • ATM2 speaker on for RX
  • ATM3 speaker on for both TX and RX
• ATO Return to data mode
  • ATO0 back to data mode, while in command mode
  • ATO1 stay in command mode (nonsense)
• ATP Use pulse dialing for the next call
• ATQ Quiet Mode
  • ATQ0 modem returns result codes
  • ATQ1 modem does not return result codes
  • ATQ2 modem does not return result codes for ATA command
• ATS Addresses An S-register
  • ATSx=y set value y in register x
• ATT Use tone dialing for the next call
• ATV Verbose mode
  • ATV0 send numeric codes
  • ATV1 send text result codes (English)
• ATX Select call progress method
  • ATX0 basic result codes: CONNECT and NO CARRIER
  • ATX1 extended result codes: CONNECT 300 and NO CARRIER 00:00:00 (call time)
• ATZ MCU (and modem) reset

Extended AT commands set

• AT&A Reverse answering frequencies
  • AT&A0 use receiving modem frequencies on answering
  • AT&A1 use originating modem frequencies on answering
• AT&C DCD Option
  • AT&C0 always keep DCD on (consider RX carrier present)
  • AT&C1 DCD follows RX carrier
• AT&D DTR Option
  • AT&D0 ignore DTR
  • AT&D1 return to command mode after losing DTR
  • AT&D2 hang up, turn off auto answer, return to command mode after losing DTR
  • AT&D3 reset after losing DTR
• AT&F Load factory defaults
• AT&J Jack Type Selection (choose OCR2A or OCR2B)
  • AT&J0 OCR2A primary, OCR2B secondary
  • AT&J1 OCR2A secondary, OCR2B primary
• AT&K Flow Control Selection
  • AT&K0 disable flow control
  • AT&K3 enables CTS/RTS hardware flow control
  • AT&K4 enables XON/XOFF software flow control
• AT&L Line Type Selection
  • AT&L0 Selects PSTN (normal dial-up)
  • AT&L1 Selects leased line (no dial, no carrier detection)
• AT&P Make/Break Ratio for Pulse Dialing
  • AT&P0 Selects 39%-61% make/break ratio at 10 pulses per second (NA)
  • AT&P1 Selects 33%-67% make/break ratio at 10 pulses per second (EU)
  • AT&P2 Selects 39%-61% make/break ratio at 20 pulses per second (NA)
  • AT&P3 Selects 33%-67% make/break ratio at 20 pulses per second (EU)
• AT&R RTS/CTS Option Selection
  • AT&R0 ignore RTS
  • AT&R1 read RTS to control outgoing flow
• AT&S DSR Option Selection
  • AT&S0 DSR line is always on, except when on-hook
  • AT&S1 DSR line follows CD
• AT&V Show the configuration (everything)
  • AT&V0 show current profile
  • AT&V1 show stored profiles
  • AT&V2 show stored phone numbers
• AT&W Store the configuration
  • AT&Wx store the profile in position x
• AT&Y Read the configuration
  • AT&Yx read the profile from position x
• AT&Z Store Telephone Number
  • AT&Z=nnn store phone number nnn in position 0
  • AT&Zx=nnn store phone number nnn in position x

Forward-compatibility set

• AT+FCLASS set the device for different modes (only data supported)
  • AT+FCLASS? show current device mode
  • AT+FCLASS=? list the supported device modes
  • AT+FCLASS=0 set the device mode to data