Radiotelephone Terminal Services

Overseas Radiotelephone Terminal in Wellington. Date Unknown.
Overseas Radiotelephone Terminal in Wellington. Date Unknown. Courtesy Chris Underwood

By Rex Johnson

International telephone requirement

Up until 1930 all public electronic communications services to and from New Zealand had been by telegraph systems with messages being sent either by radio or undersea cables. The New Zealand Government had a strong desire to implement international telephone services and this page describes the terminal services used to link radio technology to the public telephone network.

The Radiotelephone Terminal was one component of a NZ Post Office team effort to provide international telephone circuits. Other components included:

  • radio receiving and transmitting stations – physically isolated from each other to minimise interference issues,
  • transmission services to provide voice circuits to and from the radio stations,
  • the public telephone network to distribute phone calls around the country.

Early international radiotelephone circuits

The Wellington to Sydney radio-telephone link had been established from Wellington Radio ZLW in 1930. This gave New Zealand telephone connectivity to the Australian public telephone network and through their international radio circuits to the phone networks of other countries. Public radiotelephone calls were halted during the war years (from 1939) then came available again in 1945. At this time radiotelephone services were with the new Makara Radio providing the receive path and either ZLW or Auckland Radio ZLD providing the transmit path.

The war years had seen significant advances in radio technology, particularly in the area of ‘Beam Wireless’ or shortwave radio transmissions. The NZPO chose to centralise its beam wireless transmissions at a new facility in the North Island and commissioned Himatangi Radio as a high frequency (HF) transmitting station in 1953. With improving technology, links via Makara and Himatangi were able to offer more voice circuits, with better quality. We now consider the management and interconnection of the radio circuits to New Zealand’s public telephone network.

Overseas Radiotelephone Terminal

All radiotelephone voice traffic was managed by the Overseas Radiotelephone Terminal (ORT) in Wellington. Commonly referred to as Wellington Radphones, the ORT was located in the Wellington Central Telephone Exchange in Stout Street. The ORT used special voice terminals to join the separate receive and transmit radio paths onto one telephone circuit which could then be extended to the Wellington toll room for connection to the public telephone network. The ORT had operational control of radio circuits and would monitor the traffic for indications of interference or poor radio conditions. They worked closely with the receive site to ensure circuit quality was maintained and would direct the transmit station to adjust its transmitters as radio conditions changed.

Establishing radiotelephone circuits

Prearranged contact schedules were commonly used to set up regular international calls. However, shipping telephone calls were more variable. If a ship had passengers requesting telephone service it would send a telegram (by Morse code) via a coast station (Auckland, Wellington or Awarua Radio) requesting the ORT arrange a radiotelephone connection. They would also list the telephone numbers that their passengers wished to call. The ORT would send a reply telegram confirming a time and radio frequencies to use, plus advising of NZ customers that wished to call that vessel. Both parties would then pre-alert their customers to be available for phone calls at the agreed time. Regular international stations (i.e. Scott Base, Chathams or Pacific Islands) exchanged their planned caller telephone numbers with the ORT via telex message.

Near the designated time, the ORT would request the planned transmit and receive frequencies from the radio stations. For the transmit path a ‘station identification’ audio loop would be put on the voice circuit for the ship to tune its receiver to. In the early 1970s the call was a male voice reciting “This is a transmission for circuit adjustment purposes from a station of the New Zealand Post Office. This transmitter is modulated from the control terminal in Wellington. Dong, ding ding ding dong – dong” (being the sound of a xylophone being struck). Once the ORT heard the ship’s incoming tuning call they would cease the identification call, talk to the ship, then extend the circuit to the toll room for traffic to be passed.

Telephone channel multiplexers at Wellington Radphones, c1970
John Cramond, a technician at Himatangi Radio, inspects telephone channel multiplexers during a technicians’ tour of Wellington Radphones c1970. Photo: Rex Johnson. Click to enlarge.

Terminal equipment

Radio and terminal equipment constantly changed as technology evolved. By the 1970s, radiotelephone links were made using single sideband (SSB) or independent sideband (ISB) transmissions for efficiency of power and use of the radio spectrum. Terminal equipment considerations included speech privacy, ‘compander’ use (speech compressor and expander) for maximum speech quality, and improvements in operator monitoring capability. If specific compander or privacy systems were used then it was important that the other end of the radiotelephone circuit used the same equipment. This meant that most international radiotelephone terminals used the same manufacturer’s equipment.

Radiotelephone circuits were established to Australia, the United States, Great Britain and Canada. Pacific Island radiotelephone circuits were to Fiji, Rarotonga, Niue, Apia and Pitcairn Island. Other circuits were to Meteorological stations at Raoul and Campbell Islands, and to Chatham Islands and Scott Base.

Overseas radiotelephone circuits

United States (Oakland)

The first direct Wellington – USA public telephone service was provided by radiotelephone between NZPO and American Telephone and Telegraph (AT&T) stations. The service was opened in October 1945 using Makara (receive) and ZLW (transmit) sites. In 1953, the transmit services were relocated from ZLW to Himatangi Radio.

AT&T’s Pacific region radiotelephone services were provided from San Francisco. Their transmit site was KMI Dixon and their receive site was on the coast at Point Reyes, the stations being about 30 km apart and on the outskirts of the city. AT&T’s control terminal was at Grant Street in the suburb of Oakland and the radiotelephone service continued until superceded by undersea cable voice circuits. AT&T HF operations at KMI continued through until station closure in February 1999.

United Kingdom (London)

The UK link was one of the longest direct radiotelephone circuits in the world, with its radio path skimming over the edges of either the northern or southern polar regions. Auroral activity near the poles could reduce circuit quality and probably because of this vulnerability an alternative circuit was eventually introduced.

Developments with Canadian undersea cable and bearer circuits in 1956 and 1958 allowed introduction of a more stable circuit with a shorter (and non-polar) radio path in 1958. This radio link was from Wellington (Makara and Himatangi) to Vancouver on Canada’s west coast. At Vancouver the voice traffic was sent via a trans-Canada microwave bearer system to the east coast where it passed via Canada’s TAT-1 undersea cable to Britain.

The direct Wellington – London radiotelephone circuit utilised Britain’s Rugby transmitter site and Baldock receiver site, with terminal control at the International Telephone Exchange in London.

Note: The radiotelephone terminal shown in the first two pictures on the Baldock webpage (dedicated for phone calls to and from the QE2) is the same model as some of Wellington ORT’s terminals.

Australia (Sydney)

The Wellington – Sydney radiotelephone circuit was via ZLW from 1930, then Himatangi from 1953. Australian radio sites were initially operated for the Government by AWA and were at La Perouse (receiving) and Pennant Hills (transmitting). The terminal control facility was at AWA’s Headquarters, 47 York St, and was known as Sydney Radphones. [Note: Terminals shown in the second and third pictures of the Radphones website are the same model as those initially used in the Wellington ORT.] The Sydney service later moved under more direct control of the Australian Overseas Telecommunications Commission (OTC).

First Generation Terminal

(United Kingdom A, United Kingdom B, Sydney A, Shipping and Oakland)

'Mac' MacIntosh  at the Overseas Radiotelephone Terminal in Wellington. Date Unknown.
‘Mac’ MacIntosh at the Overseas Radiotelephone Terminal in Wellington. Date Unknown. Courtesy Chris Underwood

The picture above shows what we will refer to as a First Generation terminal. Each terminal has three bays, there being one voice unit bay on each end and a central service bay. This terminal type has also been seen in use at the Sydney ORT.

Second Generation Marconi Two-Voice-Unit Terminals

(Shipping, Raoul, Campbell, Niue, Apia, Pitcairn Islands)

Circuits at Wellington Radphones for Niue and Apia, seen during a technicians' tour of Wellington Radphones c1970
Circuits at Wellington Radphones for Niue and Apia, seen during a technicians’ tour of Wellington Radphones c1970. Photo: Rex Johnson. Click to enlarge.

The colour pictures of the Wellington ORT (above and below) show two bays each of dual voice-circuit terminals located immediately either side of a central patch panel for a total of eight voice circuits. This terminal type has also been seen in use at the Baldock, UK receiver site.

Third Generation Marconi Four-Voice-Unit Lincompex Terminals

(Chatham Islands, Scott Base, Rarotonga)

Circuits at Wellington Radphones for Chatham Islands, Scott Base and Rarotonga, c1970
Circuits at Wellington Radphones for Chatham Islands, Scott Base and Rarotonga, seen during a technicians’ tour of Wellington Radphones c1970. Photo: Rex Johnson. Click to enlarge.

In the photo above, the two bays to the far left are Marconi Lincompex four-voice-circuit terminals. The pink cards along the top of the second bay show three circuits designated and the terminal type has also been seen pictured at Chatham Islands and Scott Base. The first bay looks as though it has not yet been brought into service.

Circuits using Lincompex (linked compressor and expander) terminals had been measured as providing an average 22db improvement in circuit noise level, with up to 47dB noise level improvements being seen. The equipment could compensate for +/- 80Hz of frequency shift of the voice circuit that may have been introduced over SSB or ISB paths, thus maintaining high circuit quality.

Privacy capability was an option and is confirmed to have been in use on the Chatham Islands and Scott Base circuits. The privacy was ‘5-band split voice-channel’. This means that the speech circuit was filtered into five parts, then the parts rearranged and placed into some alternate re-combination in the voiceband, with optional inversion of any of the parts. The terminal at the far end would rearrange the voice band back into its original order.

How are telephone services provided now?

Australian traffic transferred to the COMPAC Cable after this section was commissioned in June 1962. United Kingdom and Oakland circuits transferred to the COMPAC cable after the Canadian section was commissioned in December 1963. By 2016 the majority of public international telephone and data services with New Zealand was carried on the Southern Cross undersea fibre-optic cable network, with a small amount of traffic carried on other cable, satellite or HF systems.

Shipping circuits moved to INMARSAT satellite telephone circuits, Raoul and Campbell Island meterological stations were automated via satellite data circuits and the stations closed, Niue has satellite service.

Apia (Samoa) is connected by cable to American Samoa and international services, and is scheduled to be connected by fibre cable to Southern Cross at Suva, Fiji in March 2017. Pitcairn Islands has three Mini M Inmarsat phones. Tonga is connected by fibre-optic cable to the Southern Cross fibre at Suva, Fiji.

Chatham Islands has a limited satellite telephone connection, Scott Base and Rarotonga have satellite service.

Ken Morse, who worked at the Wellington Transmission Centre, recalls how each day began at midnight in the ORT:

Scheduled radio contacts with ships which were written in chinagraph pencil on the Sked Board would be checked. Unusual propagation conditions announced by Australia’s Ionospheric Prediction Service, IPSO, would be consulted.

Any calls in progress would be checked on the hour, and the status of the circuits entered into the radio logs. If the signal had deteriorated, then the circuit would be taken back from the toll operators and an immediate QSY (frequency change) carried out.

As the outgoing shift headed off, a cuppa might be shared on a quiet night before the members of the team headed to their designated midnight routines. For the TO this always involved the ten past midnight sked for the weather stations at Raoul and Campbell.

More often that not, the cuppa was a snatched affair for the Technical Operator. The radio circuit for Chatham Island had to be taken down for the night and, if Scott Base had enjoyed a rare evening of favourable propagation, they too would have to be shut down when ready.

Communication with Scott Base in Antarctica was best carried out in the evening hours, provided the sun was not playing merry hell with propagation and trying to light the sky with aurorae. Wellington and Scott would meet on pre-arranged frequencies every evening and proceed to tune a “commercial” circuit. Through the background noise would come the barking huskies of Scott’s test tape – I’m convinced the tape recording had more noise on it than the radio circuit did! If man-made or natural noise was present, the receiving station at Makara on Wellington’s south coast, would be consulted. Tests would be carried out and a frequency change made to achieve an M3 quality circuit – the lowest grade allowed for private toll calls, except in an emergency.

Once a quality circuit had been achieved, the five-band privacy would be switched in to encode the speech on the radio circuit, and Scott Base was ready to go. The circuit was switched through to the Wellington TMX (manual toll exchange) and calls to family and friends could commence. The circuit needed regular monitoring as reception could rapidly deteriorate. The circuit was usually taken down by 9 or 10 in the evening.

In all my time in the radio terminal, Scott Base was only kept up round the clock on two occasions – once (for many days) when the DC10 crashed on Mount Erebus and on another occasion when a VIP on a military transport was overdue on a flight back from the ice. On the former occasion, we even managed to put up a second circuit – usually on the other sideband – for Scott so that the numerous police and air accident inspectors could carry out their work. On the second occasion, raising Scott Base in the middle of the night involved some ingenuity – and alarm at their end. After all, the cold war was still in progress at the time, and the TO at Scott feared the worst while he was trying to get his transmitter warmed up.

By the end of the doggo shift, Relda Familton would have signed off from her graveyard shift on National Radio and headed home. In the radio terminal, her voice would again be heard as the TO at Chatham Island ran their test tape for receiver tuning by the staff at Makara. A new day of skeds was beginning. “This is a single sideband transmission for receiver alignment purposes from ZLC Chatham Island. This station is operated by the New Zealand Post Office.” I can still hear her pearly tones today.

– Excerpted and published with the author’s permission from the Wild Land blog.