AN93

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.

Answering modem’s scrambled binary ones and scrambled

data; visually indis-

tinguishable from each other.

Calling modem’s Scrambled Binary Ones and Scram- bled Data; visually

indistinguishable from each other.

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.

2100 Hz Answer Tone.

DTMF dialing.

Caller Responds with SB1s and scrambled data.

Caller sends SB1s immediately.

Figure 67. Appearance of V.22 Fast Connect Protocols

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Silicon Laboratories SI2493/57/34/15/04, SI2494/39 manual Appearance of V.22 bis Protocol