Outgoing Calls - Meridian Nortel 1 Option 11C Technical Reference Manual

Outgoing calls

Table 135
Call connection sequence—near-end station receiving call
State
Line card unit idle
Call request
Outpulsing
Two-way voice
connection
Near-end station
hangs-up first
Line card unit idle
NT1R20 Off Premise Station (OPS) analog line card
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 135 on page 431). 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.
Signal/Direction
Far-endNear-end
Group on tip, battery on ring
High resistance loop
Low resistance loop
Dial Tone
Addressing signals
Ringback (or busy)
High resistance loop
Group on tip, battery on ring
High resistance loop
No battery current drawn.
Near-end station goes off-hook. Battery
current is drawn, causing detection of
off-hook state.
Dial tone is applied to the near end
station from the Option 11C.
Near-end station dials number (loop
pulsing or DTMF tones).
Option 11C detects start of dialing and
removes dial tone
Option 11C decodes addressing, routes
call, and supplies ringback tone to near-
end station if far-end is on-hook. (Busy
tone is supplied if far-end is off-hook).
When call is answered, ringback tone is
removed, and call is put through to far-
end station.
If near end station hangs-up first, the line
card detects the drop in loop current.
Line card unit is ready for the next call.
Option 11C and 11C Mini
Page 431 of 544
(Part 1 of 2)
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Technical Reference Guide