3Com U.S. Robotics 56K Voice, Command Reference Manual

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A complete list of S-Registers A-9
Error control handshaking options:
Select the total value
of bits 4 and 5
Bit 4 Bit 5 Result
0 0 Complete handshaking sequence:
V.42 Detection, LAPM error control,
MNP.
16 0 Disable MNP.
0 32 Disable V.42 Detection and LAPM.
16 32 Disable Detection phase, if you
know that the remote Business
Modem does LAPM, but not the
Detection phase.
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).
S29 20 Sets the duration, in tenths of a second, of the V.21 answer
tone.
S34 0 Bit-mapped register. See the beginning of this appendix for
information about setting bit-mapped registers.
Bit Value Result
0 1 Disable V.32bis. Used for
troubleshooting; 3Com Technical
Support may ask you to disable
V.32
bis for testing purposes.
1 2 Disable the Business Modem's
enhanced, proprietary V.32
bis
modulation. Used for
troubleshooting.
2 4 Disable the faster retrains that occur
during proprietary V.32
terbo
modulation. Used for
troubleshooting.
3 8 Enable V.23. Required for some
British connections.
Register Default Function