General Procedures / Information
FaxCentre F110 12/04 6-85
Figure 2
CLI Polarity Reversal, CLI Services
Any line voltage polarity change is used to generate a single ring detection pulse during either LIU
On- or Off-Hook. To indicate a valid polarity reversal detection no other pulse is to be allowed with-
in a defined duration !
Figure 3
On-Hook, Off-Hook Line Configuration
During terminal equipment On-Hook the line control signal is set inactive (HOOK = 0) to inhibit a
valid loop current. Due to the line voltage change, a change of the ring signal within the ring de-
tection HW-component may occur, generating an invalid polarity reversal pulse !
Pulse-Dial(External Phone)
The line voltage and current change during external phone Pulse Dial has an effect for the polarity
reversal signal (LIU_RING) as long as HOOK is kept deactivated (On-Hook). The pulse dialling
signals may generate an invalid polarity reversal detection pulse !
If a parallel phone has seized the line changing of the line voltage, due to the dialled digits, may
also generate an invalid polarity reversal detection pulse !
line
DC-voltage
- 40V
0V
+ 40V
RING
LOOP
parallel phone offhook parallel phone onhook
Ring pulse
time
line
DC-voltage
- 40V
+ 40V
0V
RING
LOOP
PolarityReversal
wait time
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