Nortel Networks 1000 User Manual

Page 130

130

NT1R20 Off-Premise Station Analog Line card

Table 55
Call connection sequence-near-end station receiving call (cont’d.)

State

Signal / Direction
Far-end / Near-end

Remarks

Ringback (or busy)

The system decodes addressing, route
calls, and supply ringback tone to near-end
station if far-end is on-hook. (Busy tone is
supplied if far-end is off-hook).

Two-way voice
connection

When call is answered, ringback tone is
removed, and call is put through to far-end
station.

Near-end station
hangs-up first

High resistance loop

If near end station hangs-up first, the line
card detects the drop in loop current.

Line card unit idle

Group on tip, battery on ring
High resistance loop

Line card unit is ready for the next call.

Far end station
hangs up first

High resistance loop

If the far-end hangs-up first, the system
detects disconnect signalling from the
trunk. The person at the near-end
recognizes the end of the call and
hangs-up.

Line card unit idle

Ground on tip/battery on ring
High resistance loop

Line card unit is ready for the next call.

For outgoing calls from a telephone, a line unit is seized when the
telephone goes off-hook, placing a low-resistance loop across the tip
and ring leads towards the NT1R20 OPS Analog Line Card. When the
card detects the low-resistance loop, it prepares to receive digits. When
the CS 1000 is ready to receive digits, it returns a dial tone. Outward
address signaling is then applied from the telephone in the form of loop
(interrupting) dial pulses or DTMF tones.

For outgoing calls from a telephone, a line unit is seized when the
telephone goes off-hook, placing a low-resistance loop across the tip
and ring leads towards the OPS analog line card (see

Table 55 "Call

connection sequence-near-end station receiving call" (page 129)

). When

the card detects the low-resistance loop, it prepares to receive digits.
When the Meridian 1 is ready to receive digits, it returns dial tone.
Outward address signaling is then applied from the telephone in the form
of loop (interrupting) dial pulses or DTMF tones.

Nortel Communication Server 1000

Circuit Card Reference

NN43001-311

02.06

Standard

27 August 2008