Silicon Laboratories SI2493/57/34/15/04 - Manual (Page 284)

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284 Rev. 1.3
Figure 66. Appearance of V.22 bis Protocol
This looks the same as the V.22 bis protocol above except for S1 signal used for signaling V.22 bis(ness) and for
start of retrains.
Figure 67. Appearance of V.22 Fast Connect Protocols
Calling modem’s
Scrambled Binary
Ones and Scram-
bled Data; visually
indistinguishable
from each other.
Answering modem’s
scrambled binary
ones and scrambled
data; visually indis-
tinguishable from
each other.
Unscrambled Binary
Ones (USB1) signal.
Two tones at 2250
and 2850 Hz.
2100 Hz Answer Tone.
The three short horizontal
lines are the S1 signal
that triggers V.22bis train-
ing. The S1 signal is an
unscrambled double
digit 00 – 01.
Caller Responds with
SB1s and scrambled
data.
Caller sends SB1s
immediately.
2100 Hz Answer Tone.
DTMF dialing.