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NT8D14 Universal Trunk card Page 595 of 894
Circuit Card Description and Installation
Trunk members are provisioned in the Trunk Data Block LD 14.
Refer to “Programming RAN trunks” on page 596 and to Software Input/
Output: Administration (553-3001-311) for instructions on service change
programs.
Continuous operation mode
In the continuous operation mode (sometimes called the Audichron mode), a
message is constantly played, over and over again. Callers “barge in” on a
playing message or receive a ringback tone until the message plays again. The
start line (ST+) is hardwired as always active. See Figure 136 on page 594.
At the end of each message, a pulse is issued on the “C” line that is used by
the trunk unit to cut through to the waiting call.
Note: The “B” (busy) signal line indicates availability of an
announcement machine message to the trunk unit when configured for
the continuous operation mode. This signal is made active (ground) by
the announcement machine if the channel contains a recorded message
and is in an online condition. The “B” line is not connected to a trunk unit
when configured for start mode operation.
Start modes (minimum vintage BA)
In a start mode (sometimes called the Code-a-Phone or start-stop mode),
playback of a message does not begin until a start pulse is received by the
announcement machine. Two subcategories of the start mode exist: pulse
start and level start.
In the pulse start mode, a start pulse activates playback of a message that
continues until completion. The announcement machine ignores all other start
pulses that might occur until the message is complete.
In the level start mode, the start signal is a “level” rather than a pulse. The
leading edge of the start signal initiates message playback that continues until
either the trailing edge of the start signal occurs or the end of the message is
reached. A message that is terminated by the trailing edge of a level start
signal is immediately reset and ready for playback again.