US Robotics COURIER User Manual page 166

COURIER HIGH SPEED MODEMS
Explanation
1. The modem is powered on and is operating at 19.2K bps or
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higher, so that it is able to connect at 14.4K bps as well as at
lower rate.
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2 . A 300-bps modem calls. The Courier senses the incoming
signal and sends the messages RING and CONNECT to the
computer. These messages are sent at 19.2K bps, the current
.
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rate .
3. Since the Courier responds CONNECT, rather than with a
rate indicator, the computer switches to 300 bps. The modem
...
automatically shifts to 300 bps to accept the data from the
incoming call.
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4.
The 300-bps data session is terminated; the modem sends the
computer the message NO CARRIER at 300 bps.
5. A 2400-bps call comes in. The modem responds RING and
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CONNECT 2400. These message are sent at the current bit
rate of 300 bps.
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6. The computer, receiving the CONNECT 2400 message,
adjusts accordingly to the higher bit rate. The modem also
shifts to 2400 bps.
7.
The 2400-bps data session is terminated; the modem sends
the computer the message NO CARRIER at 2400 bps.
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8. A 14,400-bps call comes in. The modem responds RING and
CONNECT 14400. These messages are sent to the computer
at the current bit rate of 2400 bps.
9. The computer, receiving the CONNECT 14400 message,
adjusts accordingly to the higher bit rate. The modem also
shifts to 14,400 bps.
10.
The 14,400-bps data session is terminated; the modem sends
the message NO CARRIER at 19,200 bps.
Keep in mind that whether or not your computer adjusts to these
rate changes, the Courier automatically shifts connection rates if
it is set to &NO .
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Fax and Other Operations E-15