AUTOMATIC TELEPHONES

Evening Star, Issue 20310, 19 October 1929, Page 14

AUTOMATIC TELEPHONES

PRIVATE BRANCH SYSTEM _ EXCHANGE IN MINIATURE In iliese days of liig business and the desire for the utmost efficiency possible, any firm which controls a number of departments will naturally seek an effective method partmental communication. Ino value of accuracy and speed i« incalculable, and it is clear that such factors are obtained more readily by the duect spoken word than by any .other system of transmitting and receiving message-. The telephone, therefore, is one of the business man’s greatest asse s. In Dunedin every phase ot telephony is developing in accordance with the inventions of the times. Long since, the people have learned to appreciate the convenience made possible by the big automatic exchange m Dowling street, and just recently the wondeis of the carrier current long-distance svstem has been disclosed- It seems that the time nas come to say somethin about the automatic private branch exchange, which, is proving a great boon to several .firms, in ton . It is now a few weeks since the Inei ing Star ’’ Company adopted, the new installation During tins period a system of telephonic communication one department with the other, has been thoroughly well tested H can be hailed as a. complete success—an undoubted benefit to those employed i the building, and a triumph lor the engineers of the Post and Telegraph Department. . The automatic private branch sen me works on the same principle as the main exchange. It is, m ■ short, the city installation s diminutive, but ieiy efficient brother—an exchange- m miniature. It enables the- firm handle its extensive telephone business with ease and reliability, and it also enables callers to be put at a moment s notice on the track of the department they seek. It is so arranged that within three seconds of the moment when the receiver is lifted anybody can be called to the telephone at the other end hv the ringing of the bell. The. rapidity oi communication is explained in part by the fact that it is necessary to dial only two figures. Moreover, it not only ipi ovides for inter-communication between the various branches of a concern, but it also makes it possible for any branch to have direct access to the lines connected with the main exchange. When first the receiver is lifted a prolonged and high-toned hummiim noise comes to the ears. Before dialling a number out in tho city one must first ot all dial “nought.” This action produces the deeper humming sound now so familiar to everybody. In order to provide the most, efficient service for the inquiring public the lady attendant at the switchboard has been commissioned to distribute outside lino traffic through the building. Tho private exchange is a wonderful piece of mechanism, much too technical to be described in detail. Indeed, it would require a highlyspecialised study of twenty-eight blue prints to enable the lay mind to acquire an inkling as to how the system operates. Even so. it is probable that the intricacies of tho exchange will always remain a secret, save to the Post" and Telegraph’s own engineers. There are two units at work. One handles the departmental calls, and the other serves to keep the building in touch with the city. Altogether, four lines are available for outside communication, the exchange automatically searching out an idle line. The plant is worked on a 36-volt direct current system, and in order to . charge the batteries the town supply is controlled bv a rectifier. The number of telephones that can be operated on the unit is thirty-five, and an. additional thirty-five can be installed with another unit, .

There are now several of these vate service plants in .Dunedin. They are proving very important factors in main exchange development.