ADTRAN DSU IV ESP, User Manual

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Chapter 4. Applications
61204011L1-1 DSU IV ESP User Manual 4-7
Conditions for Returning to the DDS Circuit
The DSU IV ESP can be configured to automatically revert to the
DDS circuit from the dial backup mode or wait to be returned to the
DDS manually. Once the DSU IV ESP enters dial backup mode, the
unit polls the DDS circuit once every 100 ms to determine if the
condition causing the DDS circuit failure has been corrected. Once
the DSU IV ESP determines that the problem has been properly
corrected and the DDS circuit is stable, it will wait for the amount
of time specified in the restore timer (1 to 255 minutes) before
reverting to the DDS circuit. Polling of the DDS circuit is non-
intrusive and return to the DDS circuit generally takes 2 to 3
seconds. The backup connection is maintained for one minute after
the DDS circuit is restored.
See Chapter 9, Configuring Dial Options on page 9-1 for more detailed
information.