Chapter 3: AT Commands Reference
June 30, 2008 AT Commands Reference Manual 3-285
The following table shows the different S-registers and their associated values.

Note: S0 (Auto Answer) should work regardless of the DTR HW line state. This is a deviation

from the ITU V. 25-ter standard.
Sn Description Min Value Max Value Default Value
S0 Sets/gets number of rings before
auto answer. 0 255 0
S2 Sets/gets escape code character. 0 255 43
S3 Sets/gets carriage return code
character. 0 127 13
S4 Sets/gets line feed code character. 0 127 10
S5 Sets/gets command line editing
character (backspace). 0 127 8
S7 Sets the number of seconds in
which connection must be
established before the call is
disconnected.
1 255 30
S12 Sets/gets guard time (in units of
50 msec) for the escape character
during CSD connections
0 255 20
S14 Read-only. Holds values of En
(in bit 1),
Qn (in bit 2), Vn (in bit 3).
— — 170
S21 Read-only. Holds values of &Dn
(in bits 2, 3 and 4), &Cn (in bits 5
and 6).
——40
S22 Read-only. Holds values of Mn
(in bits 2 and 3),
Xn (in bits 4, 5 and 6)
— — 134
S31 Read-only. Holds value of Wn (in
bits 2 and 3). ——0
S36 Sets/gets value of \Nn. 0 7 5
S39 Read-only. Holds value of &Kn
(in bits 0, 1 and 2). ——3
S40 Read-only. Holds value of \An
(in bits 6 and 7). — — 192
S41 Read-only. Holds value of %Cn
(in bits 0 and 1). ——3