See also How were Intelsat 1 “Early Bird” and Telstar 1's "hundreds" of simultaneous telephone conversations multiplexed/demultiplexed?

Ouch! The 1960's

The Intelsat 1 “Early Bird” communications satellite, built by Hughes Aircraft Co., was able to relay 240 simultaneous phone conversations between Europe and North America.

From This Is What Broadband Satellite Communication Looked Like in 1965

The Intelsat 1 “Early Bird” communications satellite, built by Hughes Aircraft Co., was able to relay 240 simultaneous phone conversations between Europe and North America. But having all 240 lines apparently originate in one room in Los Angeles, as this Hughes publicity shot seems to suggest, would undoubtedly have created a slight bottleneck.

I have read that in the early 1960's Telstar 1 and 2 were the first satellites to route long distance telephone calls.

I seem to remember that long, long ago, long distance (overseas?) phone calls did have noticeable latency and sometimes annoying echoes, and I suspect that this was due in part to the light time from Earth to a satellite and then back to Earth, and the echoes were because these were analog signals.

These days, long distance phone calls are generally routed through fiber optic cables, and I assume that ground telephone traffic if still relayed by satellite, would be digital.


  1. When did they stop routing conventional analog telephone calls through satellites as analog signals as opposed to digitized data?
  2. At its peak, what was the volume of telephone traffic that was routed through satellites? It can be expressed either in total number of concurrent calls, or calls per year, whichever is easier to find.

note: I'm asking about calls made between conventional telephones, and not satellite phones.

enter image description here

Mounting Telstar Satellite to the Thor-Delta rocket 1962 (Source: Nokia Bell Labs and AT&T Archives)

Source: The First Active Orbiting Communications Satellite

Then, for the first time, live television transmissions and phone signals could be relayed between the US and Europe by means of this simple looking, spherical black and white satellite. Its iconic exterior held within it 170 pounds of some of the most complex electronics known to humankind. It featured 3,600 solar cells for power and a traveling-wave tube for amplifying the radio signals. Back in 1962, the key task of the Telstar 1 was to receive signals beamed from the USA, amplify them 10 billion times and rebroadcast them to live audiences in Europe, and vice versa. TV and telephone communication signals were relayed and boosted to get back down to Earth. The Telstar 1 circled the planet every two and half hours. It was only in the right position to beam transmissions between the USA and Europe for 20 minutes in each orbit before dropping out of contact. Future satellites were designed to work in tandem with each other, seamlessly passing the broadcast to keep transmission live at all times. At launch, the Telstar 1 facilitated over 400 telephone, facsimile and television transmissions.

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    $\begingroup$ fyi I found a giant list of communications satellites at Colorado State University, though not sure how helpful it is i this case. $\endgroup$
    – uhoh
    Sep 1, 2019 at 1:11
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    $\begingroup$ There's a fascinating paper here oecd.org/sti/ieconomy/2091239.pdf that sheds some light, but not a full answer. I learned a lot about comsats and COMSAT from reading through it. $\endgroup$ Sep 1, 2019 at 1:24
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    $\begingroup$ @OrganicMarble thanks for that. This might be a challenging question to answer accurately. For example per Table 16, in 1991 there were 565 US transponders. Assuming 36 MHz equivalent (which the table doesn't) that's 20+ GHz of bandwidth. However customers can divvy up each transponder's bandwidth between phone, TV, and other things any way they like. I think a rough answer will be fine, though it's possible somewhere there's a quantitative estimate already published. $\endgroup$
    – uhoh
    Sep 1, 2019 at 1:32
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    $\begingroup$ @OrganicMarble: re: satellite comms in Australia. Because of low population rates in rural & remote parts, they still can have satellite comm. Generally Australia uses both undersea cables & satellites for international telecommunications (NBN Slymuster) $\endgroup$
    – Fred
    Feb 28, 2021 at 16:12
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    $\begingroup$ Nice "archeology" type question. May I comment with: when the term "call" will stop being used? We are definitely entering the era of "always on" and "video chats" (multi-party virtual meeting"). Before we paid according to distance and duration. Today, some of us pay according to "volume" used (per month), and some even don't). Tomorrow, we will pay according to network coverage alone ("do you cover Europa?"). $\endgroup$
    – Ng Ph
    Dec 10, 2021 at 9:57


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