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AT Command Set Summaries 21
4
AT Command Set Summaries
Basic AT Command Set
Command Options Function & Description
A/ Re-execute the last command string
<any
key>
Terminate the current connection attempt when entered in handshaking
state
All the following commands require an “AT” prefix
A Go off-hook and attempt to establish a connection without waiting for a
ring
Bn Line modulation options
B0 Select V.22 mode for 1200 bps connection
B1 * Select Bell 212A for 1200 bps connection
B2 Select V.23 1200 bps for receiving, 75 bps for transmitting in originate
mode; 75 bps
for receiving and 1200 bps for transmitting in answer mode
B3 Select V.23 75 bps for receiving, 1200 bps for transmitting in originate
mode; 1200 bps for receiving and 75 bps for transmitting in answer mode
B15 Select V.21 for 300 bps connection
B16 Select Bell 103 for 300 bps connection
Dn Dial command, beginning the dialing sequence. The string “n” (telephone
number and modifiers) listed as follows is entered after the “D”
command
L Re-dial last number. Should be the first character following ATD,
ignored otherwise
P Pulse dial.
R Reverse dial. Originate call in answer mode (go on-line in answer mode)
S=n Dial the phone number stored in NVRAM at location “n” (n=0, 1, 2, 3)
T DTMF tone dial.
W Wait for second dial tone. The modem waits for the second dial tone
before processing the dial string
, Pause. Cause the modem to pause for a time before processing the next
character in the dial string (specified by S8 register)
! Hook Flash (for call transfer). Cause the modem to go on-hook for 0.5
second then return to off-hook
@ Wait for 5 seconds of silence after dialing number
; Return to command state after dialing a number without disconnecting
the call
En AT command echo options
E0 Echo disabled
E1 * Echo enabled
Hn Switch-hook control
H0 * Modem goes on-hook
H1 Modem goes off-hook
Mn Speaker control
M0 Speaker always off
M1 * Speaker on until carrier present