Specifications

Si2493
Rev. 1.3 23
Table 8. Basic AT Command Set (Command Defaults in Bold)
Command Action
$
Display AT command mode settings.
A
Answer incoming call
A/
Re-execute last command. This is the only command not preceded by “AT” or followed by a
<CR>.
Dn
Dial
The dial command, followed by 1 or more dial command modifiers, manually dials a phone
number:
Modifier Function
! or & Flash hook switch for FHT (U4F) ms (default: 500 ms)
, or <
Pause before continuing for S8 seconds (default:
2 seconds)
; Return to AT command mode
@ Wait for silence.
G
Polarity reversal detect. By placing the “G” character in
the dial string (i.e. ATDTG1), the Si2493 will monitor the
telephone line for polarity reversals. If a busy tone is
detected, the Si2493 will report “POLARITY REVER-
SAL” if a polarity reversal was detected or “NO POLAR-
ITY REVERSAL” if a polarity reversal was not detected.
In each case, the result code is followed by “OK”. If the
S7 timeout occurs before a busy tone is detected, the
Si2493 will report “NO CARRIER”. Polarity reversal
monitoring begins after the last digit is dialed and ends
when the busy tone is detected or S7 timeout occurs.
Note: It is not possible to establish a modem connection
when using this command.
L Redial last number.
P
Pulse (rotary) dialing—pulse digits: 0, 1, 2, 3, 4, 5, 6, 7,
8, 9
T
Tone (DTMF) dialing—DTMF digits: *, #, A, B, C, D, 0,
1, 2, 3, 4, 5, 6, 7, 8, 9.
W
Wait for dial tone before continuing for S14 seconds
(default: 12 seconds). Blind dialing modes X0, X1 and
X3 do not affect the W command.
If the DOP bit (U7A, bit 7) is set, the “ATDTW” com-
mand will cause the ISOmodem® to pause dialing and
either report an “OK” if a dialtone is detected or “NO
DIALTONE” if a dial tone is not detected.
En
Local DTE echo
E0
Disable
E1
Enable
Hn
Hook switch.
H0
Go on-hook (hang up modem).