Nortel Networks 311

40 Overview

the transmit B bit between 0 and 1 (0 during ring on, 1 during ring off), and

ground on the tip lead by setting the transmit A bit to 0. When an incoming

call is answered (by the terminal equipment going off-hook), the terminal

equipment simulates tripping the ringing and shutting off ringing by causing

the lineside T1’s receive A bit to change from 0 to 1. The Lineside T1

card responds to this message by simulating loop closure by holding the

transmit B bit constant at 1.

Outgoing Calls During outgoing calls from the terminal equipment, a

channel is seized when the terminal equipment goes off-hook, simulating a

ground to the ring lead toward the Lineside T1 card by causing the lineside

T1’s receive B bit to change from 1 to 0. In turn, the Lineside T1 card

simulates grounding its tip lead by changing the transmit A bit to 0. The

terminal equipment responds to this message by removing the ring ground

(lineside T1’s receive B bit is changed 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 farend might disconnect the call.

If the Lineside T1 port has been 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 ter minated 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.

•In order 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 doesnot provide

battery reversal indication when a call is answered; it only provides

battery reversal indication when a call is disconnected.

•In order to detect distant end disconnect for calls terminating on the

Lineside T1 card, the "hook ﬂash" feature within the SAL softwaremust

be enabled.

•In order 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.

Nortel Communication Server 1000

Circuit Card Reference

NN43001-311 01.04 Standard

Release 5.0 23May 2008