3 - AT Commands, S-Registers and Result Codes
29
Command: F
n
Echo Online Data Characters
Values:
n =
1
Default: 1
Description: F0 Enable online data character echo. (Not supported.)
F1 Disable online data character echo (included for
backward compatibility with some software).
Command: H
n
On-Hook/Off-Hook Control
Values:
n
= 0 or 1
Default: 0
Description: H0 Go on-hook to hang up.
H1 Go off-hook to make the phone line busy.
Command: I
n
Information Request
Values:
n
= 0–4
Default: None
Description: I0 Display default speed and controller firmware
version.
I1 Calculate and display ROM checksum (e.g.,
“12AB”).
I2 Check ROM and verify the checksum, displaying
OK
or
ERROR
.
I3 Display default speed and controller firmware
version.
I4 Display firmware version for data pump (e.g., “94”).
Command: L
n
Monitor Speaker Volume
Values:
n
= 0, 1, 2, or 3
Default: 2
Description: L0 Select low volume.
L1 Select low volume.
L2 Select medium volume.
L3 Select high volume.
Command: M
n
Monitor Speaker Mode
Values:
n
= 0, 1, 2, or 3
Default: 1
Description: M0 Speaker always off.
M1 Speaker on until carrier signal detected.
M2 Speaker always on when modem is off-hook.
M3 Speaker on until carrier is detected, except while
dialing.