Section 1: From Toy to Exchange-Based Service

When Alexander Graham Bell invented the telephone in 1876, it was at first greeted sceptically. The head of the telegraph monopoly in the United States, Western Union, labelled it an electrical toy. But before the end of the century every major city in the world had a telephone service - and the telegraph companies were competing for ownership.

The crucial element in this back flip: the invention of the telephone exchange.

Bell envisages the telephone exchange

Bell himself saw the need for exchanges. The evidence is an early letter to supporters, in which he lists all the key functions of present-day telephone exchanges:

"... cables of telephone wires could be laid underground, or suspended overhead, communicating by branch wires with private dwellings, counting houses, shops, manufactories, etc., etc., uniting them through the main cable with a central office where the wire could be connected as desired, establishing direct communication between any two places in the city...".

Other ideas covered in Bell's letter are curiously familiar. An operator, placed in a central office, to connect telephone wires as needed. A fixed annual rental for the use of wires. And, he pointed out, since all connections would pass through a central office, the connection times for calls could easily be noted - and bills sent out periodically.

Networks vs direct wiring

Now, it is taken for granted that we need only as many telephone lines as there are telephones. But without exchanges, telephones could only operate if they were wired to each other - a situation of mind-boggling impracticality. For example: five telephones could be interconnected using 10 wires - but 1000 telephones would need nearly half a million criss-crossing wires.

NOTE: The connection between a telephone and an exchange is referred to as a line, regardless of the number of wires it includes - at times, as many as five wires (see section 2 of this Kit).

Subscribers - or "subs"

In the early days, callers were known to telephone companies as "subscribers" - people who subscribed to an exchange rather than installing their own lines and telephones. While vestiges are still to be found in acronyms such as STD (Subscriber Trunk Dialling), the term subscriber has now gone out of fashion.

Manual exchanges: the pioneers

The first telephone exchange opened in New Haven, Connecticut, in January 1878. Others - including Melbourne, in August 1880 - were hard on its heels. Also among the first wave were Brisbane (less than two months after Melbourne) and Sydney (1881).

As Bell envisaged, these exchanges were manual. All employed operators - mostly young women - who, on request, connected the caller's line to another line and noted the call (for later billing). In other respects, the exchanges differed, each finding its own way of meeting the requirements of a public exchange.

These requirements included:

• A way for callers to alert the operator
• A way for operators to alert the call recipient
• A simple, practical method for connecting pairs of lines.
• Some early solutions included:

Alerting the operator

When a caller lifted the receiver, an electrical signal was transmitted down the line, causing a small metal shutter on the operator's board to drop down. A quick scan of the board then showed her which lines needed attention.

Alerting the person being called

Many shutters and bells were tried. The eventual choice was a magneto bell, devised by Bell's assistant Thomas Watson.

Connecting the two lines

Again, many systems were tried. Thomas Edison (who also invented the carbon telephone transmitter), devised one of the simplest and best. It had a series of horizontal metal bars, insulated from an equal number of vertical bars.

Each line was connected to one horizontal bar and one vertical bar. At every crosspoint, each bar had a hole. To connect (say) line 3 to line 14, the operator would push a metal peg into the hole where bar 3 crossed bar 14. That allowed the current to flow between the two lines, and the conversation could begin.

Edison's system reached its limits as the volume of calls grew. As a single operator could not handle the calls, several switchboards were needed, each connected to a sub-section of the total lines. But that entailed a new problem: how to connect a call on one board to a line on another?

Various solutions were tried, all less than ideal. At around 1000 lines, the thickets of criss-crossing wires resembled a forest and it became evident that the switchboard had to be redesigned.

Patch cords and multiple switchboards

The arrangement that replaced Edison's system was as follows:

• Instead of the system of crossed bars, each line had its own socket. The sockets were arranged in a large grid, and the operator used a patch cord - an insulated wire with a plug at each end - to connect any two of them.
• Multiple switchboards replicated this arrangement, and each board could access every line. Since the work could be shared by as many operators as needed, exchanges could have thousands of lines - and hundreds of calls every minute.

While that arrangement solved the traffic problem, another difficulty arose: a socket could be free on one switchboard but busy on another. If the operator were not to interrupt conversations, she needed advance warning of the line's status.

Again, different solutions were devised. At some exchanges, connecting a line on one board took all the corresponding sockets out of circuit. At others, the operator tested the socket and received a status signal (such as a buzz or a light).

Going long-distance

Eventually, exchanges were connected by trunk lines. While it was then fairly simple for operators to connect calls to other exchanges, it was practicable only if long-distance calls remained a small proportion of the traffic. Accordingly, a surcharge was imposed, making trunk calls much more expensive than local calls.

The service tradition

While December 1991 saw the last of Australia's manually operated exchanges (at Wanaaring, NSW ), many of the services that grew up around manual exchanges remain. Some, such as time requests, are now Dial-It™ services. Others, such as call redirection, have become programmable options on modern telephones.

Today, operators still connect some calls - such as overseas calls for customers without access to International Direct Dialling (IDD). And people are still employed for certain service tasks, such as fault reporting and directory assistance. But it is now a century since machines began to share - then take over- the work of connecting local calls.

A wired country

The TV series, "A Country Practice", holds in a time capsule the part played by manual exchanges in Australia's not-so-distant past. "Beverley", the manual operator, is invisible but ever-present. She personally connects every call, knows every inhabitant of Wandin Valley by name, and keeps tabs on the leading characters' movements for the purposes of call redirection. And - when cars crash or children are lost in the bush - she remains on duty, personally masterminding the town's relief effort.

The next chapter concerns that initially controversial replacement of the manual exchange: A.B. Strowger's automatic exchange.