Avaya Nortel Communication Server 1000 Reference page 53

to 1) and simulating open loop at the terminal equipment (lineside T1's receive A bit is changed
to 0).
Call disconnect from far end PSTN, private network or local station
While a call is in process, the far end might disconnect the call. If the Lineside T1 port is
configured with the Supervised Analog Line (SAL) feature, the Lineside T1 responds to the
distant end disconnect message by opening tip ground. This causes the Lineside T1 card to
change the transmit A bit to 1. When the terminal equipment sees the transmit A bit go to 1, it
responds by simulating open loop causing the lineside T1's receive A bit to change to 0. The
call is terminated and the interface is once again in the idle condition.
For the Lineside T1 card to support distant end disconnect in ground start mode, the following
configuration parameters must exist:
• The Supervised Analog Line (SAL) feature must be configured for each Lineside T1
port.
Note:
By default, the SAL feature opens the tip side for 750 m/s in loop start operation. This
is configurable in 10 m/s increments.
• To detect distant end disconnect for calls originating on the Lineside T1 card, the "battery
reversal" feature within the SAL software must be enabled. Enabling the battery reversal
feature does not provide battery reversal indication when a call is answered; it only
provides battery reversal indication when a call is disconnected.
• To detect distant end disconnect for calls terminating on the Lineside T1 card, the "hook
flash" feature within the SAL software must be enabled.
• To detect distant end disconnect for calls originating and terminating on the Lineside T1
card, both the "battery reversal" and "hook flash" features within the SAL software must
be enabled.
Call disconnect from Lineside T1 terminal equipment
Alternatively, while a call is in process, the terminal equipment may disconnect by going on-
hook, causing the lineside T1's receive A bit to change to 0. The Lineside T1 card responds
to this message by simulating the removal of ground from the tip by changing its transmit A bit
to 1. The call is now terminated and the interface is once again in the idle condition.
Table 5: Ground Start Call Processing A/B Bit Settings
A and B bit settings in each state of call processing.
Table 5: Ground Start Call Processing A/B Bit Settings
Idle
Incoming Calls (to terminal equipment):
Idle
Circuit Card Reference
State
on page 53 outlines the lineside T1's
Transmit Receive
A B A
1 1 0
1 1 0
Line cards
B
1
1
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