• Belfast Between The Wars

TELEPHONE HOUSE, BELFAST: MOST COMPLETE SYSTEM IN THE WORLD, 10,000 LINES

Northern Whig, Wednesday 6th March 1935


SKILLED ENGINEERS BUSY AT WORK


In a modernistic embryo skyscraper, towering above the Belfast rooftops, a small army of skilled engineers and artificers are busily engaged on the thousand and one details of what will ultimately be the most up-to-date telephone system in the world.


WIZARDS IN OVERALLS


A “Northern Whig” representative who toured Telephone House yesterday found humble wizards in overalls hard at work bringing order into the apparent chaos of miles of multi-coloured wires, acres of bright new switchgear, and long bays of Robot-like machines which do everything but think.


Although the automatic system will not come into operation until the latter part of the year good progress has already been made at Telephone House. Much remains to be done, however, in connection with the installation of new instruments in subscribers’ premises, the diversion of underground cables, and the equipment of the nine new satellite exchanges – East, North, Dundonald, Stormont, Ormeau, Malone, Fortwilliam, and Dunmurry.


Telephone House itself is designed for 10,000 lines, though it is expected that at the outset only about 5,600 will be accommodated. The total number of exchange lines in the area within a five mile radius is approximately 13,000, while extensions bring up the aggregate of stations to 18,000.


Before the change-over every subscriber will be supplied with a temporary switch, many of which have already been fitted. At the time immediately preceding the change-over each line will be connected to both the present manual system and the new automatic system. Subscribers will be asked at a given moment to throw over the switch, linking up with the new system, and simultaneously the four existing exchanges will be replaced by the ten new ones.


SPEED IN HANDLING CALLS


The “step by step” automatic system will be worked on the five digits method, under which the first digit (or in some cases the first and second) represent the exchange, the remainder standing for the subscriber. Bewildering to the layman in their intricate ingenuity, the various pieces of apparatus are designed to combine reliability of unattended working with a speed in handling calls far superior to that of the manual system.


Like a setting from a futurist film of the “Metropolis” type is the room housing the main distribution frame. Here all cables from the street are terminated, the apparatus serving two purposes, protection against power lines and also a safeguard against lightning storms. On one side subscribers’ lines enter in a medley, and on the other, without a single manual operation, they are sorted into street numerical order. Subsequently, however, on an upper floor the intermediate distribution frame throws the lines out of numerical order again. The object of this is to mix busy lines with those which carry a less number of cables, thus equalising the load on the switches.


LINE FINDER


The line finder in use is a comparatively new model, which can handle a group of 200 subscribers’ lines, whereas one of the old switches had to be allocated to each subscriber. If, however, there are on an average, say, six calls at once on any given group, a corresponding number of line finders is required.


From the line finder the incoming call is passed on to the first selector. As soon as the requisite number is dialled the “finger” of this remarkable device rises to the level of that number. It then hunts in the bank for a free junction to the next series of selectors. The process is repeated until the final selector takes in order the last two digits and puts the subscriber through to the number called. If this number is engaged the “busy” sound is automatically given.


In the intermediate distribution room if a switch is faulty or for some reason is held up for three minutes it automatically sends out an alarm. There is a series of directional alarm lamps, and a bell also calls the attention of the maintenance man. All he has to do is follow the lamps.


Another uncannily clever machine is the automatic routine tester, which can be set to test a certain group of line finders. When it finds the faulty section it sounds an alarm and holds the switch in the position in which it is faulty.


There is a separate room for call meters. Each subscriber has one of these compact little machines, which wait until the number called has responded before registering the call.


All telephone subscribers will await with interest the inauguration of the system, the date of which will be notified in due course. It is a difficult matter to estimate the exact time occupied in putting through an average call automatically, but, according to an official, in normal cases the actual dialling by the subscriber will occupy much the longer part of the operation.


To view photographs of Telephone House (including the amazing machinery) on National Museums NI's website click here.


The building features in Ulster Architectural Society's exhibition and online tour, 'Glamour & Gloom: 1930s Architecture in Belfast' which you can register for online by clicking here.