Ericsson LBI-39001 Instrukcja Operatora Pobierz pdf (Strona 5)

MD110

The MD110 is an Ericsson Private Branch Exchange (PBX). Its primary building block is the line interface module

(LIM). The LIM performs all call processing functions. One LIM interfaces to the PI and either the Public Switched

Telephone Network (PSTN) or another PBX. It contains two to four circuit board cards which connect to a common

backplane. The backplane includes a processor bus and a device bus. The processor bus carries control data between the

device processors on the individual boards. The device bus carries voice or data to and from device boards.

In addition to the LIM, the standard MD110 has an alarm unit, an Ericsson dial-back modem for remote configuration, a

two-hour battery back-up, and up to eight on-premises extensions that allow a telephone to be directly connected to the

MD110 for testing purposes. A 386 PC for configuring the MD110 is optional.

The MD110 will also have one or more termination lines to the PSTN or another PBX. All types of digital and analog

trunks and tie lines are available based on customer needs. In addition, the MD110 will always have one digital ISDN T1 or

E1 trunk for connecting to the PI.

Multiplexer (MUX)

The Multiplexer (MUX), also called a Channel Bank, is used to combine 4-wire balanced audio inputs from the IMC,

bound for the Public Switched Telephone Network (PSTN), into a single digitized stream, and vice versa. In North America

and Japan the standard is a T1 multiplexer, and in Europe, Asia, and South America the standard is an E1 multiplexer.

A single T1 allows up to 23 voice circuits to be multiplexed together. A single E1 allows up to 30 voice circuits to be

multiplexed together. Each voice circuit has its own channel unit within the MUX.

PBX Interface Module (PIM)

Within the IMC, a PBX Interface Module (PIM) provides an audio path and a control signaling interface for Jessica. The

PBX Interface Module contains a controller card and up to eight audio cards.

1.2. OPERATION

Telephone interconnect messages can be initiated from an EDACS radio or from a telephone. This section describes the

processes that occur when a telephone call is implemented.

Radio-Originated (Outbound) Calls

When a radio user initiates a telephone interconnect call, the radio sends an interconnect request message to the control

channel. This message incorporates the digits to be dialed. The system forwards the call request message via the downlink to

the IMC. The IMC routes the request to Jessica via the PBX Interface Module in the IMC. Meanwhile, the originating radio

is directed to a working channel in preparation for the call connection.

The Jessica PBX Interface receives the call request message and translates it into a telephone call setup. The PI then

initiates the call setup using the PRI ISDN interface card. The PRI message is sent to the MD110. The MD110 routes the

call to the PSTN or customer-owned PBX. The PSTN then routes the call to the destination telephone. The PSTN indicates

to the MD110, which in turn notifies the PI, that the telephone terminal is ringing. The PI notifies the IMC, which in turn

generates ringing tones that are sent to the initiating radio.

When the telephone is answered, the PSTN indicates to the MD110, which then indicates to the PI, that the party being

called has answered. The connection is now established between the originating radio and the telephone terminal, and the

conversation proceeds.

Either the telephone user or the radio user can terminate the call. If the telephone user hangs up first, the PSTN notifies

the MD110, which indicates to the Jessica PI that the telephone party has disconnected. The PI sends a drop message to the

IMC, and the message is passed to the site where the radio has been assigned a channel.

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Ericsson LBI-39001 Instrukcja Operatora Strona 5