Nortel Networks 311 Message waiting, Analog line supervision

Line cards 33

Message waiting

Line cards that are equipped with the message waiting feature receive

notiﬁcation that a message is waiting across the Card LAN link (IPE

cards). On cards that drive a message waiting light, the light is tur ned on

by connecting the ring side of the telephone line to the –150 V dc power

supply. When the line card senses that the telephone has gone off-hook,

it removes the –150 V dc voltage until the telephone goes back on-hook.

Line cards that use an interrupted dial tone to indicate message waiting do

nothing until the receiver is pickedup. The line card then interrupts the dial

tone at a regular interval to indicate that a message is waiting.

In both cases, the message waiting indication continues until the user

checks his or her messages. At that time, the system cancels the message

waiting indication by sending another message across the Card LAN link

or network loop.

Analog line supervision

Analog line supervision features are used to extend the answer supervision

and disconnect supervision signals when the line card is connected to an

intelligent terminal device (Keysystem or intelligent pay phone). Twotypes

of analog line supervision are provided:

•battery reversal answer and disconnect supervision

•hook ﬂash disconnect supervision

Battery reversal answer and disconnect supervision Battery reversal

answer and disconnect supervision is only used for calls that originate from

the terminal device. It provides both far-end answer supervision and far-end

disconnect supervision signals to the terminal device. In an intelligent

pay phone application, these signals provide the information necessary

to accurately compute toll charges.

In the idle state, and during dialing and ringing at the far end, the line card

provides a ground signal on the tip lead and battery on the ring lead. See

Figure 8 "Battery reversal answer and disconnect supervision sequence"

(page 35). When the far-end answers, these polarities are reversed. The

reversedbatter y connection is maintained as long as the call is established.

When the far-end disconnects, the system sends a message that causes

the line card to revert the battery and ground signals to the normal state

to signal that the call is complete.

Hook Flash disconnect supervision Hook ﬂash disconnect supervision

is only used for incoming calls that terminate at the terminal device (typically

a Keysystem). See Figure 9 "Hook ﬂash disconnect supervision sequence"

(page 36). The disconnect signal is indicated by the removal of the ground

connection to the tip lead for a speciﬁclength of time. The length of time

Nortel Communication Server 1000

Circuit Card Reference

NN43001-311 01.04 Standard

Release 5.0 23May 2008