Nortel Networks 311

674 NT8D14 Universal Trunkcard

"RAN control signals (Control GRD = IDLE)" (page 670). 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 star t and levelstar t.

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.

In a start mode (sometimes called the Code-a-Phone or start-stop mode),

playback of a message does not beginuntil a star t pulse is received bythe

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. See Figure 213 "RAN control signals (Control

GRD = IDLE)" (page 669). The announcement machine ignores all other