PRACTICE
553-2201-184
CALL TO
SL-I
SET
Page 4-2
(14)
CE detects dialing and removes dial tone at start of dialing.
(15) CE encodes dialed information.
(16) Ringback
tone on the dam output bus is applied to SL-1 set over
audio pair during message time slot assigned by CE (busy tone
received if called number is busy).
4.03 Talking Connection. Called number answers.
(1)
(2)
(3)
Ringback tone is removed by CE.
Digital voice on dam output bus is applied to SL-1 set via
multiplex control, PCM codec, digital-to-analog filter, hybrid
transformer and audio pair during message time slot.
Analog voice on audio pair from SL-1 set is applied to dam input
bus via hybrid transformer, analog-to-digital filter, PCM codec,
multiplex control, and buffer (during time slot).
4.04 Terminating the Call. Assume SL-1 set goes on-hook first.
(11
On-hook message is transmitted from set to line circuit.
(2)
Signaling on data output bus changes: SL-1 set lamp extinguishes.
.-
(3)
ADD inputs removed (no signaling for line circuit
01.
(4)
Line circuit enable inputs are removed (message time slot is no
longer assigned to line circuit).
(5)
Circuitry in IDLE condition, ready for next call.
4.05 Signaling to the
TerminaLIn
time slot 0, CE scans
each
line on
the
(1)
(21
loop-in sequence.
CE has call for line circuit 0.
CE determines line circuit 0 is idle (no signaling from circuit on
data input bus during time slot
01.
(31
(41
(5)
(6)
(7)
(8)
(9)
CE assigns message time slot for audible signaling (from time slots
1 through
31).
Line circuit is enabled during time slot 0.
Visual signaling data on data output bus during time slot 0 is
applied to multiplex control. Visual signaling data is applied to
SL-1 set over signaling pair.
Signaling is detected by SSD (Line lamp of SL-1 set flashes).
PCM codec is enabled during message time slot.
Audible signaling applied to SL-1 set via digital-to-analog filter,
hybrid transformer and audio pair.
SL-1 set signaled audibly (tone ringing).
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