3Com 56K Command Reference Manual page 187

Register Default Function
Bit
3
4
5
7
0
16
0
16
S28 8 Sets the duration in tenths of a second of the extra
3000/600 Hz answer tones sent during V.32 hand-shaking.
This gives V.32 modems additional time to connect in V.32
mode before timing out.If there is difficulty answering
older, manually operated V.32 modems (for example,
modems that require a button to be pushed in order to dial,
try lengthening the duration of the extra tones).Setting S28
to zero eliminates the extra tones resulting in a faster
connect time if, for example, the Business Modem is set to
use V.21 modulation (300 bps) or V.23 modulation (1200
bps).
S34 0 Bit-mapped register. See Chapter 1, Using the AT
Command Set, for instructions about how to set
bit-mapped registers.
Bit
0
Value Result
8 Disable 2100 Hz answer tone to allow
two V.42 devices to connect more
quickly.
16 See next page.
32 See next page.
128 Unusual software incompatibility.
Some software may not accept some
result codes. This setting disables the
codes and displays the 9600 code
instead. The call's actual rate can be
viewed on the ATI6 screen.
Error control handshaking options:
Select the total value of bits 4 and 5.
0 Complete handshaking sequence:
V.42 Detection, LAPM error control,
MNP.
0 Disable MNP.
32 Disable V.42 Detection and LAPM.
32 Disable Detection phase, if you know
that the remote modem does LAPM,
but not the Detection phase.
Value Result
1 Disable V.32bis. Used for
troubleshooting; 3Com Technical
Support may ask you to disable
V.32bis for testing purposes.
S-Registers I-5