3-8 NT5K19 Analog Tie Trunk Card
553-3001-173 UK Trunk cards description
Receive signals
All received signals are in the form of Earth-On or Earth-Off applied to the
E wire. Earth-On is the application of ground to the E wire through a
resistance of 1500 ohms. Earth-Off is the application of ground to the E
wire through a resistance of greater than 400K ohms. In both Earth-On and
Earth-Off conditions, a grounded 1µF capacitor is applied to the M wire.
Idle state
In the Idle state, the M wire receives an “Idle signal” from the Meridian 1
and is placed in the Earth-Off condition.
Seize
To place an outgoing call, the Meridian 1 at the near end sends a seizing
signal through the M-wire to the far end. The incoming end (far end)
recognizes the seize signal, busies the circuit against outgoing calls, and
prepares to receive digits. The continued receipt of the seizing signal by
the far end is accepted as a “hold” signal.
Dialing
Digits are sent through the near end M wire in the form of 10 pps pulses of
the Earth-Off condition or DTMF digits.
Answer
When the called party answers, the far end sends an “answer” signal
through the M wire.
Call disconnect
Either party can disconnect the call by applying a clear signal to the M
wire. The far end applies a “clear back” signal, while the near end applies
a “clear forward” signal. The circuit remains busy until both clear forward
and clear backward signals have been exchanged.
Table 3-4 provides a summary of NT5K19 DC-5 signalling states.
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