Paddington Telephone Exchange Hacking

ITMC PaddingtonThe First Australian International Phone Hack

by Robert Brand

In researching the first telephone exchange to be installed at the OTC Paddington terminal, Peter Bull today came across this reference. It is from a very well documented site on Australian Communications.

The large increase in telephone channels resulting from COMPAC gave rise to the need for advanced methods of switching and Australia’s first automatic international telephone exchange entered service on December 3, 1963, in conjunction with the commissioning of the cable. It was a 4-wire, register controlled, crossbar type 5005T, designed and manufactured by the British firm. Automatic Telephone and Electrical (AT&E) Co. Ltd., and supplied by TEI and installed by OTC personnel at the Paddington terminal under the guidance of two engineers from AT&E. The initial 5005T installation comprised one x 100 line router with dual common control and was equipped for 50 international lines, 45 junctions for the handling of outgoing international calls and 50 junctions (via second stage route switches) for the connection of incoming calls to the national network.

The international signalling system employed was the CCITT Interim Telephone Signalling System No. 5, which had previously come into use in the Atlantic but had not been applied before over such long international circuits as existed between Sydney, North America and the United Kingdom and the use of echo suppressors to control echo on the long international cable circuits was also a new development for Australia. Much of the assembly and wiring of relay sets of the 5005 exchange was undertaken by TEI at their Meadowbank works near Sydney, the work in general being related to the special application of CCITT No. 5 signalling, national loop-disconnect register signalling and special code conversion requirements.

The major changes which the Australian network was undergoing as crossbar switching and seven digit numbering were being introduced, made it desirable to insulate the international network from the frequent changes occurring in the APO network, to provide for international practices which were not possible in that network and to enable the APO to initiate calls from gateways in distant capital cities. The international exchange was, therefore, equipped to perform some unusual, perhaps unique, functions. The principal ones were:

  • For calls incoming to Australia, a ‘number converter’ was provided, so that overseas telephonists need dial only an Australian subscriber’s ultimate number in the Australian numbering scheme.
  • For calls outgoing, a special dummy digit in the dialling train triggered the generation of international function signals which did not exist in the Australian network.

The above is from TECHNOLOGY IN AUSTRALIA 1788 – 1988

A condensed history of Australian technological innovation and adaptation during the first two hundred years. Compiled by Fellows of the Australian Academy of Technological
Sciences and Engineering.
MELBOURNE 1988. ONLINE 2000. Updated 21 November 2001.

I remember the old exchange being in use when I was a trainee in 1969. It was about halfway through my training that the new Ericsson switch went into service. I believe the TEI switch only allowed 2VF and Decadic traffic on the national side, but I am happy to be corrected. With the new Ericsson switch came the changeover from 2VF and Decadic to MFC, but there were plenty of 2VF and Decadic channels in use for the next decade.

The picture below shows the national telephony trunk racks. The left most one was pretty much solely 2VF (2VF stood for Two Voice Frequencies) Australia Paddington OTC ITMC National Trunks

The First Australian International Phone Hack

Idle minds did not mean idle activity. Many things were innovation, but occasionally there were many times where the idle time activity was just plain fun and mischief. One day someone got the idea of seeing if we could route a call through the national network from a standard phone to make an international call. Since International Direct Dialling was not possible in the Australian national network, this would take some doing and as I remember it, we took some 6-8 weeks to crack the method, but crack it we did!

There was a lot of activity for a while seeing if we could get a call through the telephone exchange using 2VF as a bit of a challenge. It was fun to show people that even before International Trunk Dialling (IDD) we could get a call through to the Paddington exchange and hear a recording saying that your international call failed. Our hacked call always failed to get past the national junction on the 2VF rack. We could watch the call connect on our rack, but fail to progress. To make the next leap to dialing a number, I created a 2VF set of oscillators (600Hz and 750Hz) in a lunchbox with batteries. It had a dial and I was able to get through the international exchange to a destination overseas. The hack was successful and myself and another (un-named ITMC person – well known) were able to make this happen. The other person got concerned when a Telecom guy from Tasmania called him asking how he did it. Our fellow exOTCer was forced to go to Head Office and spill the beans about our party trick. Oddly enough since we could dial the world at work, it was not seen as a fraud issue. Especially with him taking it too HO before the word got around. Telecom were able to block the loophole and that was that.

The trick was to make a hop to the 2VF network from the new STD network. There were secret codes that operators used to get to smaller towns that were not as yet on MFC at the time. Then there were a series of codes that let you jump from town to town and then we could get back to the OTC Paddington exchange. Luckily we had a book that detailed all the codes.With the 2VF box, you just had to connect to the international exchange by 2VF and then press the release codes on the 2VF switches on my lunchbox. This dropped the 2VF register and then I would simply seize the circuit via 2VF and dial the number. There was a set of tones to accept an answer signal and you were on the call and all for the cost of a local STD call to somewhere like Gosford.

There were many more crazy activities on the national network. More for another time. Unfortunately I lost the lunch box with the switches and telephone dial a long, long time ago.

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