3-10 NT5K19 Analog Tie Trunk Card
553-3001-173 UK Trunk cards description
Table 3-5
NT5K19 tone-on and tone-off signalling
Si gna ll in g d ir ect io n
To ne- On
To ne- Of f
Tr ans mi t
Si gnal l i ng tone of 2280 H z
+/ - 5 Hz
Re mova l of t he Si gnal l i ng
t one
Re cei v e
Si gnal l i ng tone of 2280 H z
+/ - 15 Hz
Any f r equency or
c ombi nat i on of f r equenci es
wi t h t ot al pow er l es s than
- 40 dBmO
Tone-on signals are received at two power levels, high and low, depending
on the length of the tone. Table 3-6 summarizes tone-on power levels.
Table 3-6
NT5K19 tone-on receive levels
Du rat i on o f t o ne
Hi gh /L ow To ne- On
dB L evel
l es s than 300 m s
Hi gh
- 4 t o -2 0 dBm O
300 to 550 m s
Hi gh
- 4 t o -2 0 dBm O
gr eat er t han 550 ms
Low
- 14 to -30 dBm O
Idle state
In the idle state, the PBX machines at both ends of the circuit apply an idle
signal to indicate they are free to accept incoming calls. Both PBX
machines are in the tone-on condition.
Seize
To place an outgoing call, the outgoing PBX applies a seize signal to the
signalling path. The outgoing PBX is now in the tone-off state. The PBX
at the incoming end recognizes the seize signal, busies the circuit against
outgoing calls, and prepares to receive digits.
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