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Restoral Options
7) Enter a phone number in the address selected by the Default Dial option
(AT DA), under the ACU OPT'S menu. To use the Link Phone # option
(AT LN), enter a phone number in each address to be used.
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8) During a dial restoral, if you want the modem to disconnect from the dial line
automatically after a specified interval, set the D to L (Dial to Leased) option
under the RESTORAL OPT'S menu (in the originate modem only). If you
want to hold the dial line and test the leased line after this interval, set the Hold
Dialine option under the RESTORAL OPT'S menu the same in both modems.
While operating in dial restoral, the modem periodically returns to the leased
line (according to the time interval specified in the Dial to Leased option), to
test the line in an attempt to reestablish the leased line connection. If, during
21 seconds, the modem fails to qualify the leased line, data transmission
resumes on the held dial line. If the modem successfully establishes a valid
connection on the leased line (within 21 seconds), it holds the dial restoral
connection for the period of time set in the Hold Dialine option. The modem
passes data on the leased line while holding the dial line.
If a retrain occurs while the modem is testing the leased line, the test is
terminated and the modem returns to the dial line.
After the timer expires, if the leased line is qualified, the dial line is dropped
and data transmission resumes on the leased line.
If the leased line qualification fails (the leased line cannot be qualified after 21
seconds, or if a retrain is initiated), another attempt to qualify the leased line is
made according to the time specified in the Dial to Leased option.
NOTE: When operating with peer-to-peer, or alternate destination restoral,
the Hold Dialine option should be set the same in both modems involved with
restoral. In peer-to-peer restoral, two leased line modems are involved in
restoral. In alternate destination restoral, the remote leased line modem and a
local dial modem are involved in restoral. Refer to Figures 1-2(A) and 1-2(B)
in the “AT HD (Hold Dial Line)” section of Chapter 1, AT Commands, for
examples of peer-to-peer and alternate destination restoral.
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9) Make sure that the PSTN option (AT MD), under the MODULATION
OPT'S menu, is set to On.
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10) To use error correction, set the Mode option (AT CA), under the
MODULATION OPT'S menu, to Reliable, Auto Rel, or Spd AutoRel.
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While operating on the leased line, if the Mode option is set to any of the
Reliable settings (Reliable, Auto Reliable, or Speed-Dependent Auto
Reliable), it is treated as if Mode=Reliable. If the Mode option is set to a
Reliable setting, while restoral is operating, that setting is treated normally.
Restoral Options 2-11