Handbook for Sound Engineers

Intercoms 1567

intended receiver is free so he can reinstate the call or

the system can automatically recall the receiver.

Call Forwarding. Call forwarding allows all calls

directed to a station to be forwarded to another station.

Call Reply. When the called person is absent, the caller

may dial a call-back signal which indicates that he has

been called.

Call Transfer. Particularly useful for transferring a call

to or from a secretary.

Camp On. Camp-on is a feature which allows the caller
to camp-on to the called person when that person is in
communication with someone else. Once the called
person hangs up, the caller is automatically connected
to him. Normally, camp-on only holds on for 10–20 s
before dropping out, or may remain in service until the
next call is initiated.

Central Answering Service. Units can be set up to go
through a central answering person with automatic
queuing of incoming calls.

Conference. Conference calls can be held with more

than one party. Normally three to four parties is the

maximum limit, however some systems may be

expanded to a 30 party conference.

Display Features. Today’s intercoms usually use an

LCD type display system which gives the called or

calling station number, in addition may display a series

of preprogrammed messages, whether or not the called

station is in privacy mode and time/date.

Group Callback. Many systems are setup so that

various groups can be connected with one button so a

person can call an entire group at one time.

Hands Free. In this condition, conversations are hands

free from anywhere in the room as long as it is a duplex

system. This can be changed to confidential at any time

by a person picking up the handset and operating as a

telephone system.

Hurry Up. If the conversation channel is busy, and the

caller needs to make an emergency or an important call,

Figure 43-8. Ring Master Intercommunications Crisis Alert System at Toronto-Pearson International Airport. Courtesy of

Ring Communications, Inc.

Infield

Terminal

(62 stations)

A = RS 485 to fiber transceivers

A

Stage 12Copper

exchange

(164 stations)

A

Stage 10Copper

exchange

Park Garage

(9600 cars)

(144 stations)

A

Stage 11Copper

exchange

Central

Utilities

Facilities

(58 stations)

A

Stage 5 Copper

exchange

Firehall #2

(6 stations)

A

Stage 2 Copper

exchange

APM

Parking

(6 stations)

A

Stage 4 Copper

exchange

Terminal 1

Comm Rm 1

(354 stations)

A

Stage 6Copper

exchange

(248 stations)

A

Stage 7Copper

exchange

(150 stations)

A

Stage 8Copper

exchange

Terminal 3

(80 stations)

A

Stage 9Copper

exchange

APM

Building

(23 stations)

A

Stage 13Copper

exchange

(65 stations)

A

Stage 12Copper

exchange

(28 stations)

A

Stage 14Copper

exchange

Terminal 1

Comm Rm 2

Park Garage

(9600 cars)

Terminal 3

Comm Hub

Airport

Train Sys

Firehall #1

(3 stations)

Central

Workshop

Facility

(8 stations)

Stage 1

exchange

(120 stations)

Main

Control

Center

Digital

Network

Controller

Train 1

exchange

(6 stations)

Train 1

exchange

(6 stations)

Security

Gate

Firehall 2

Remote

Stations

Toronto-Pearson

International

Airport

Radio link

w/VOIP

Radio link

w/VOIP

Fiber link

8 km

Fiber link

7.4 km

Fiber link

8.4 km

Fiber link

7.4 km

Fiber link

7.2 km

Fiber link

5.4 km

Fiber link

5.4 km

Fiber link

6.4 km

Fiber link

5.7 km

Fiber link

5.7 km

Fiber link

7 km

Fiber link

9 km

Fiber link

8.7 km

Copper link

0.5 km

Copper link

1 km

Copper

link

0.5 km

Copper

link

2.3 km