[HN Gopher] AT&T's Abandoned Microwave Tower Network (2017)
___________________________________________________________________
AT&T's Abandoned Microwave Tower Network (2017)
Author : ecliptik
Score : 164 points
Date : 2021-10-09 14:32 UTC (8 hours ago)
(HTM) web link (99percentinvisible.org)
(TXT) w3m dump (99percentinvisible.org)
| themodelplumber wrote:
| That's a great resource, thank you.
|
| I learned just a little about these after making the decision
| that my drives through Nevada would never again be boring. Once I
| started asking questions about what I was seeing, the "ice cream
| cones" or horn antennas really did stand out in a fascinating
| way. And $25K to buy one does seem like it could be a terrific
| deal in the right situation.
|
| Another thing I asked about: When I stopped to get gas or
| groceries, I realized there were tall visibility flags on the
| back of so many Nevadan trucks, even what looked like personal
| vehicles. I had overlooked them for years. An interesting dive
| into an industry and its culture started there.
|
| BTW, speaking of old towers that went up for sale and are
| possibly interesting to ham radio operators: Here's one near me
| (NorCal Bay Area) that was purchased by a local bay leaf grower
| and then opened for ham radio use--in exchange for a
| refurbishment effort.
|
| https://www.youtube.com/watch?v=GMtkLjHUgYU
| [deleted]
| bombcar wrote:
| What are the flags for?
| dmd wrote:
| http://www.miningwhips.com/
| themodelplumber wrote:
| Yep, this.
| nitrogen wrote:
| They are also for off-road recreational use, e.g. in sand
| dunes.
| ipdashc wrote:
| Love seeing these get brought up. It's a really fascinating
| system from an era when communications infrastructure was a bit
| more visible. It's one of those things where, once you learn it
| exists, you'll start seeing them (the towers/horns) popping up
| all over the place.
|
| My favorite AT&T artifact, though, has gotta be the Project
| Offices: https://en.wikipedia.org/wiki/Project_Offices
|
| The gist of it seems to be that these are secure, physically
| guarded, literal underground bunkers built into the tops of
| mountains along the East Coast, housing troposcatter antennas and
| satellite dishes. Super cool. As far as I can tell, nobody ever
| truly figured out exactly what they're for, and most are still
| operational today. I tried driving up to one once, out of
| curiosity, and there are some pretty intimidating "stay out of
| here" signs and cameras, even at the very base of the mountain.
|
| Chances are they were simply just meant for the military AUTOVON
| network, mentioned near the top of this thread. But I suppose
| that doesn't explain why they're still operational nowadays.
|
| https://coldwar-c4i.net/ATT_Project/index.html (Funny enough,
| this website is maintained by the same Albert LaFrance who runs
| long-lines.net, mentioned in the article)
|
| https://coldwar-c4i.net/ATT_Project/VA01/ATTsiteB.html
|
| This one is actually decommissioned and has pictures of the
| inside: https://coldwar-c4i.net/ATT_Project/Buckingham/index.html
|
| Super interesting stuff, IMO
| js2 wrote:
| Wild. I've lived 30 minutes from the one in Chatham for 15
| years and never heard of it before.
|
| https://www.flickr.com/photos/legeros/albums/721576916034825...
|
| http://www.thetownofliberty.com/2018/01/the-mystery-of-big-h...
| [deleted]
| dunham wrote:
| My dad used to work on these towers in the midwest. Back in the
| day, he told me that they still had plenty of capacity, but AT&T
| had to switch to fiber after Sprint "dropped the pin".
| kzrdude wrote:
| Interesting. Is there no corresponding podcast episode for this
| story?
| cenazoic wrote:
| The Qwest Tower building in Minneapolis referenced in the article
| has been the CenturyLink Building since 2011, and the microwave
| was removed in 2019:
|
| ref: https://www.startribune.com/after-50-plus-years-the-
| centuryl...
| rsync wrote:
| ... and is the most beautiful Central Office (CO) building in
| the United States.
| EGreg wrote:
| Does AT&T still send you microcells?
| gpvos wrote:
| Of course, many countries have had a similar network. I like the
| towers of the Netherlands, which have similar designs to each
| other, even though each is unique. A few have a radio mast on
| top. Click the links at the bottom of
| https://cellnextelecom.nl/over-cellnex/locaties/ to get an
| impression. Currently they are mostly used as data centres, but I
| think they still provide some microwave links as well.
| diskzero wrote:
| I lived directly across the street from one of the "Long Lines"
| towers on Queen Anne Hill in Seattle, WA. [1]
|
| It was actively maintained, with various antenna arrays being
| attached or removed frequently. The building below was packed
| full of gear and service vans were coming and going all the time.
|
| I was sorely tempted to try and climb it over the various years I
| lived in Seattle, but decided it wasn't worth either the arrest
| or death by electrocution or ground impact!
|
| 1.
| https://www.google.com/maps/place/315+W+Galer+St,+Seattle,+W...
| walrus01 wrote:
| the queen anne site is a wireline CO for that region, and has
| cellular stuff on it. The 6 GHz microwave has been out of
| service for many years. It used to be a primary link across the
| sound, to things in Kitsap, and similar.
|
| fairly typical USWest/Qwest central office otherwise.
| psim1 wrote:
| I used to live next to one of these! It was a useful landmark:
| turn right at the tower. There was also an underground bunker
| next to it that someone bought in recent years and attempted to
| make into living quarters.
| NelsonMinar wrote:
| We've got networks like this all over rural America. Only instead
| of giant towers they're little consumer fixed wireless nodes,
| getting 1-25Mbps (or more!) via 2.4GHz. 5GHz if you're lucky.
| Goety wrote:
| A lot of broken links in that article
| genocidicbunny wrote:
| How serendipitous, I was just watching a show Bob Moses [1] did
| on one of these towers above LA, and was wondering what they
| were. Now I've my answer.
|
| 1. https://www.youtube.com/watch?v=xKeduffv7_U
| mbostleman wrote:
| Any reason AT&T isn't removing and disposing of these towers?
| walrus01 wrote:
| AT&T sold most of them off in the early 2000s. American Tower
| owns a lot of them. Some others went to individual private
| owners. There's a company in western MT that owns about five of
| the mountain top sites for instance. Very few of the
| rural/suburban sites are still owned by AT&T. The sites where
| AT&T still happens to be the ILEC in an area may have horns on
| a roof just because they're very expensive and a huge hassle to
| decommission.
| folkhack wrote:
| So some of the towers are still in AT&T's ownership but a ton
| of them got sold off to American Tower for resale and leasing
| space.
|
| People do everything from run cellular on them, run datacenters
| in the nuclear hardened bunker sites, etc. Even though they're
| old as heck and look like something out of a sci-fi many
| structures are still solid and some of the sites have things
| like diversified utilities.
|
| Then finally, there's the EPA... these towers can be a
| nightmare for EPA - specifically the ones with backup generator
| fuel tanks that were buried. I'm guessing AT&T didn't want to
| deal with the complex logistics of digging those up, horn
| removal, etc. and just sold many of the properties off.
| Aloha wrote:
| The ones that are still in AT&T's ownership also have fiber
| co-sited at them, usually on former coax routes, like this
| former main station between Colorado springs and Amarillo.
|
| https://www.google.com/maps/place/37deg55'27.3%22N+102deg36'3
| 6.5...
|
| There is still active microwave, but its usually in the
| ownership of the RBOC/IOC not a long distance carrier, and is
| used to link the end office to the rest of the PSTN.
| Microwave is also used extensively to link cell sites to
| other cell sites, so you need to install less fiber.
| folkhack wrote:
| Huh - looked at that location on street view and it is _so
| weird_ seeing a modern AT &T logo on a Long Lines site
| building!
|
| Microwave backhaul fascinates me... I think the most
| interesting example of it that blows my mind is the private
| backhauls that are going up between major financial hubs in
| the US like Chicago <-> New York. Since latency is a huge
| deal for a lot of these HFT traders some intense stuff gets
| engineered:
|
| https://arstechnica.com/information-
| technology/2016/11/priva...
|
| Specific quote I'm referencing:
|
| > The researchers then used the FCC and other records to
| deduce that, at the time of their 2013 study, there were 15
| (!) networks licensed to operate microwave links between
| the two cities.
|
| Freakin' wild!
| pmorici wrote:
| Microwave back haul in telecom networks is still very prevalent
| the difference between what this article describes and modern
| day is how it is used. Now days the microwave part of the
| network is usually regional to connect groups of towers in a
| local area to a central location that has fiber or satellite
| access into the main network. This older system was doing the
| job of what fiber does today serving as the main cross country
| network.
| throwawayboise wrote:
| THey don't actually own many (most?) of them anymore. Most have
| been sold and are owned by a handful of "tower operating"
| companies who will lease space on the tower. The ones in areas
| with no other market for radio towers have been/are being
| scrapped.
| astronautjones wrote:
| most of them are just on top of mountains or hills
|
| http://long-lines.net/places-routes/index.html
| trimbo wrote:
| The one I grew up near was eventually sold to Crown Castle, now
| used as a cell tower.
|
| https://long-lines.net/places-routes/Lake_Zurich_IL/index.ht...
| grendelt wrote:
| Cost. Several of them are hosting cell and radio services so
| that "pays the rent" on the location.
|
| Dismantling and scrapping such a tower would be enormously
| expensive and bring no value to AT&T shareholders.
|
| If they're in total disrepair, I'm sure a case can be made for
| safety in an urban area. The two towers closest to me are in
| rural areas with several other radio service tenants where
| maintenance is a covered cost.
| Aloha wrote:
| Legacy AT&T owns almost none of them anymore, what's left are
| owned by the RBOC (often the other AT&T) and as you note,
| have a prohibitive removal cost and are in urban centers.
| aasasd wrote:
| I'm gonna guess that spending money on that seems a highly
| dubious investment.
| mistrial9 wrote:
| safety and clean-up are always a cost center, on the books.
| dboreham wrote:
| Almost all the sites are still in use due to the resurgence
| in terrestrial wireless use in the past 20 years.
| aeharding wrote:
| Many of these towers are also used for other equipment as well,
| and not abandoned.
|
| It's also worth mentioning that big equipment like this isn't
| designed to be removed from towers, and not only would be
| expensive to remove, but extremely dangerous. It's a lot safer
| and cheaper to just leave it there, and mount additional
| equipment (cellular equipment, etc) elsewhere on the tower.
| kzrdude wrote:
| But it will rust and eventually fall down, so doesn't the
| cost show up at some later point anyway?
| dboreham wrote:
| The tower sites are maintained.
| tyingq wrote:
| There's usually other antennas on the tower for cellular or
| VHF/UHF, so the tower itself is maintained. And the
| microwave horns and waveguide are typically aluminum and/or
| copper.
| Y_Y wrote:
| This is the famous Japanese method known as _katamari_.
| ugjka wrote:
| Also known as bird killers
| rsync wrote:
| If you spend any time in the mountains you will see "blank"
| billboards up in the hills. These are "passive repeaters"[1] for
| microwave networks and I am surprised they weren't mentioned in
| the article ...
|
| [1] https://en.wikipedia.org/wiki/Passive_repeater
| walrus01 wrote:
| Here's a 1984 vintage PDF for passive microwave repeater
| engineering:
|
| https://az276019.vo.msecnd.net/valmontstaging/vsna-resources...
|
| For the most part these are almost obsolete, the typical data
| link that many of them carried was one DS3, or at most, three
| DS3... The path loss is extreme. Usual setup was to go from a
| small town central office (CO), 3-5 km up to a nearby mountain,
| then bounce it off there, and 25-30 km to another nearby
| mountain. With big old power hungry PTP microwave gear that
| occupied a full 42U rack, took 1200W of power, and carried a
| whole lot of DS0.
|
| Nowadays a modern PTP microwave radio that can carry 1400Mbps
| full duplex in the 6 or 11 GHz bands is as little as 35W of
| power, so many hilltop tower sites either have built electrical
| grid connections, off grid solar, or whatever.
|
| Building some of those passive repeater billboards in places
| with no road access was very costly. Big helicopter bills and
| very labor intensive.
|
| You can still see a number of them on hillsides in eastern
| Oregon.
| JCM9 wrote:
| Many small towns still have these telephone microwave towers
| around if you know what to look for.
| embedded_hiker wrote:
| Here is a site in downtown Portland OR:
| https://www.google.com/maps/@45.5230331,-122.6802471,3a,75y,...
| throwawayboise wrote:
| There is one along the road on my way to work. It's still used,
| but the microwave horn antennas have been replaced by cellular
| network antennas.
| Zigurd wrote:
| The AT&T Long Lines network predates the use of digital radio
| for telecommunications. It used analog FDM to carry multiple
| calls. These towers have lasted because they, and the radio
| equipment, were designed to survive a nuclear war. (Another
| reason the fiber transition happened quickly was that fiber was
| more survivable.)
|
| There are many new microwave links being deployed now using
| modulation techniques for digital data.
| flyinghamster wrote:
| Cell carriers often use microwave backhaul as well,
| particularly when fiber infrastructure is unavailable. These
| are usually smaller dishes mounted on cell towers, rather than
| big horn antennas.
| pixl97 wrote:
| Where I used to live in East Texas there was one of these,
| well, at least a few decades ago. Never knew exactly what it
| was for. But it is a mirror image of the pictures. The things
| you learn later in life because of the internet.
| __turbobrew__ wrote:
| There is one in Vancouver BC. I always wondered what is is:
| https://goo.gl/maps/RKVvfiDApVxCWsnj7
| walrus01 wrote:
| The Telus CO downtown at Robson and Seymour used to have a
| large tower on the roof with 6GHz horns, linked to that site,
| and towards the site on Bowen Island which still has horns.
| Bowen Island was a link to the sunshine coast, across to
| Nanaimo, and many other places.
|
| There is also a big site out in the fraser valley on a
| hilltop that was part of the long lines network with shots
| going east towards Hope (trans canada microwave) and down
| into Whatco County.
| mtippett wrote:
| I had just moved to Toronto in about 2002, and was waiting for an
| interview. I saw one of those microwave horns on a building in
| the distance. Puzzling over what it was.
|
| Interview started, talking about something glanced over the
| background and muttered verbally "Microwave" as it hit me that it
| was a microwave waveguide of some sort.
|
| Didn't get the job...
| ksec wrote:
| Why is the Title Edited ?
|
| >Vintage Skynet: AT&T's Abandoned "Long Lines" Microwave Tower
| Network
|
| The original title of the article, actually make sense in the
| subject of "Long Lines". But the submitted title make it sounds
| like AT&T totally abandoned Microwave Network. I dont know about
| AT&T but Microwave Network is still actively being used today and
| refined even in the latest 5G 3GPP Spec Rel 16, 17 and 18.
|
| Other than that it is a nice piece and history of the system.
| walrus01 wrote:
| PTP microwave is very much in use by many carriers, it's
| absolutely essential for a lot of modern cellular network
| builds. But the actual microwave horn antennas in the 6 GHz
| band, that typified the inter-city AT&T long lines network, are
| 98% decommed in place these days. You would be very hard
| pressed to find a site that still has the waveguide, waveguide
| pressurization system, and a live FCC part 101 licensed 6 GHz
| radio running on a horn-to-horn path.
| tyingq wrote:
| A similar thing happened in the US military. There used to be a
| system where voice, radar info, and data were relayed back from
| the front lines of a conflict via a system of portable microwave
| stations.
|
| Some of them short (<~50 miles) links with horn antennas like you
| see in this article. Longer links with parabolic dishes and
| tropospheric scatter. All "portable" equipment on camouflaged
| trucks and trailers that could be unloaded and assembled
| anywhere.
|
| All of that started being replaced in the mid-90's with a
| combination of dedicated military satellite equipment and more
| use of commodity stuff like small commercial microwave network
| bridges, cellular phones, satellite phones, and so on. They
| closed out the "microwave tech" jobs and folded them in with
| "satcom" or other specialties.
|
| Some of the equipment:
|
| https://en.wikipedia.org/wiki/AN/TRC-97
|
| https://www.marines.mil/Photos/igphoto/2001740716/ (apparently
| still used by the Marine Corps)
| folkhack wrote:
| > A similar thing happened in the US military
|
| I'm not saying you're incorrect that the military had similar
| tech to what AT&T had, but I'll split the hair that they
| actually worked together hand-in-hand.
|
| They actually populated AT&T Long Lines towers with AUTOVON
| equipment which was the old military phone system in the US.
| Also used the same switching network to support Air Force One
| with the Echo Fox Presidential Aircraft network. Some of the
| locations were hardened for nuclear attack.
|
| https://en.wikipedia.org/wiki/Autovon
|
| http://www.coldwar-c4i.net/Echo-Fox/index.html
| tyingq wrote:
| That may be true for some equipment in the miltary. The ones
| I'm talking about were standalone and portable, for use in a
| war zone. The only connections they would make to non-
| military equipment was after the voice/data was de-muxed into
| channels. That could be connected to phone lines, etc.
| Typically, though, pretty far downstream after passing
| through different equipment.
| folkhack wrote:
| In response to a post about the AT&T Long Lines network,
| saying something "similar" happened in the military seems
| disingenuous because they were absolutely partnered on the
| _same_ project. To imply something is "similar" typically
| implies that it is separate to some degree - that's not the
| case with AT&T and the US military in regards to the Long
| Lines Network.
| tyingq wrote:
| Sorry, that just makes no sense to me. I'm talking about
| mobile military equipment that talked microwave only to
| other mobile military equipment. Equipment that would be
| deployed in a war zone, where AT&T probably wasn't
| present. Like a connection between a forward air control
| post and a rear echelon camp. Both being (typically) a
| bunch of tents and vehicles in the middle of nowhere.
| Downstream from that was voice/data channels that
| wouldn't care what AT&T or anyone else was doing.
|
| You seem to be talking about military use of FIXED (not
| portable/tactical) microwave, which is a different space.
| folkhack wrote:
| > You seem to be talking about military use of FIXED (not
| portable/tactical) microwave, which is a different space.
|
| Which is what the original post/article was about - the
| fixed terrestrial microwave network that AT&T ran...
| which was a major joint effort with the US military.
|
| Sorry I got caught up on "similar" being confusing when
| the military was 100% involved with what the original
| post was discussing (specifically the AT&T Long Lines
| network) - I regret my comments.
| imwillofficial wrote:
| Folkhack, You're simply wrong. Stop arguing when you
| don't possess firsthand knowledge.
|
| (I see you've added a new culpa, no worries! We all learn
| new stuff)
|
| Wanna go down a rabbit hole? Remember that spectrum sale
| in the 2010s? What if I told you the FBI had their own
| microwave network that they divested of around that time?
|
| Interesting stuff!
| folkhack wrote:
| > You're simply wrong
|
| Specifically - what am I wrong about? As-per HN
| guidelines specify exactly what I have said that is
| factually incorrect? Please quote it directly if you can,
| and in good faith provide sources so I can better inform
| myself.
|
| I simply disagree that I'm wrong about anything that I've
| stated here - I have specifically visited a Long Lines
| AUTOVON switching site; 100% the US military was
| partnered with AT&T for this. I actually possess first-
| hand knowledge on this - I've met with site owners.
|
| > I see you've added a new culpa, no worries! We all
| learn new stuff
|
| OK? Honestly I was just trying to be polite and it was
| less of an apology and more taking the passive road out
| when we were obviously talking about two separate things.
| I don't disagree with anything that tyingq was saying - I
| was just trying to make a nuanced point regarding the
| partnership between AT&T and the US Military which is
| directly related to the article that was originally
| posted. Somewhere wires got crossed and I just decided to
| bow out as politely as I could.
|
| Sometimes socializing on this site really weirds me out.
| Please, in good faith: what have I factually said that is
| incorrect here?
| imwillofficial wrote:
| No prob! Specifically this: "To imply something is
| "similar" typically implies that it is separate to some
| degree" So the US military has many microwave comm
| projects. ATT was only one of them that was left unused.
| Many had no ATT involvement whatsoever. So yeah, military
| had contracts with ATT, but those were a tiny subset of
| microwave efforts.
|
| Former Submarine communications specialist here.
| awslattery wrote:
| Army 25P (microwave systems MOS) is still around iirc (at least
| in the Reserves), and speaking from personal experience,
| 25Q10EAC was still getting dedicated 10 week training on tropo
| and DGM enclosures in 2012 at AIT.
|
| That EAC rider was certainly rare, but we were told tropo was
| still in play in South Korea, and as late as 2015, another
| company in my reserve ESB had a few tropo systems they were
| still maintaining and training on.
|
| But yes, by and large, most microwave-based signal MOS were
| rolled into either point-to-point "multichannel transmissions"
| (25Q) by which a good part of your qualifications include
| deployment of satellite transportable trailers (STT), SMART/T
| systems (shared with the Marines),and the Phoenix system; and
| the dedicated SATCOM MOS (25S).
| technol0gic wrote:
| as a former 25U and 25A i've heard stories of what happened
| to birds that landed on that tropo ::shudder::
| spacecadet wrote:
| My family leases land in Maine for one of these towers. They are
| still maintained.
| sgt101 wrote:
| BT built a system of underground copper pipes/waveguides for
| microwave transmission in the 1970's - it never got beyond a
| testing platform in Suffolk (Martlesham Heath to Wickham Market)
| due to fibre optics becoming the clear winner.
| walshemj wrote:
| And some above ground waveguides alongside a main road near
| Ipswich - not sure if they are still there.
| Aloha wrote:
| AT&T built one as well, the WT4/WT4A system.
|
| https://archive.org/details/bstj56-10-1829
| bogomipz wrote:
| Also worth mentioning that MCI, an AT&T competitor and thorn in
| their side, also had a microwave relay network. The M in MCI is
| for microwave. There's some great info on MCI here:
|
| https://telephoneworld.org/long-distance-companies/the-histo...
|
| MCI was a real innovator and an important part of internet
| history. Vincent Cerf worked for MCI[1]. Sadly they were
| relegated to the dustbin of history as a result of the WorldCom
| scandal[2] and are now sadly just a part of Verizon Business.
|
| [1] https://en.wikipedia.org/wiki/Vint_Cerf
|
| [2] https://en.wikipedia.org/wiki/WorldCom_scandal
| aasasd wrote:
| > _Built in the early 1950s... It conveyed phone conversations
| and television signals from the era of the Kennedy assassination
| through the resignation of Nixon_
|
| Even from the other side of the globe I can tell that it seems
| strangely short-lived. Built for a decade, then used for a
| decade?
|
| Wikipedia notes tersely:
|
| > _The launch of communication satellites in the 1970s provided a
| cheaper alternative._
| magila wrote:
| Technology advanced extremely quickly from the 40s to the 70s.
| Much of what was built in that time became obsolete soon after
| it was completed.
| allturtles wrote:
| I think this is wrong. AFAIK satellites have never been a
| significant channel for domestic phone calls.
|
| Microwave relays were obsoleted by fiber optics.
| alrs wrote:
| > Like their predecessor satellites, the Telstar 3 satellites
| operate at 6/4 GHz (C band). Simultaneous long distance
| telephone call capacity is 21,600. The satellites furnish
| voice, video, and high speed data services.
|
| https://www.telcomhistory.org/resources/online-
| exhibits/scie...
| allturtles wrote:
| Perhaps I was overly categorical. Certainly satellites
| could be used for telephone calls, but my impression is
| that this was never a dominant use, except maybe for
| overseas calling (given the expense of undersea telephone
| cables).
|
| e.g. I found this government report report from 1983
| stating that "microwave is the chief means of transmitting
| long-distance telephone calls..." in the U.S., this is well
| after the advent of satellites: https://www.google.com/book
| s/edition/A_Five_year_plan/NbGS1A...
| retrac wrote:
| In the 1920s, 3 and 12 channel frequency multiplexing on
| twisted pair was introduced. It made most single-channel long
| links obsolete within about a decade.
|
| In the early 1930s, both time and frequency multiplexing were
| introduced on coaxial cable, carrying up to 600 channels per
| conductor, it rendered the above twisted pair multiplexed lines
| obsolete within about a decade.
|
| c. 1950 microwave relay is introduced (the AT&T long lines in
| question here) and undergoes explosive growth, with the cross-
| continental system linking most major cities built by 1960, and
| reaching essentially every part of the country by 1970. Such
| links could carry hundreds of megabit/s worth of data (or
| multiple 6 MHz TV analogue channels). Much cheaper than
| coaxial, it largely halted new coax installations. It would
| remain dominant into the 1980s, so more like 20 years.
|
| Fibre optic communication was introduced in the mid-1970s.
| Immune to atmospheric problems, less path loss, potentially
| capable of carrying far more data than microwave. It made most
| of the microwave systems obsolete by the 1990s.
| Aloha wrote:
| They were used up until the mid-90's really.
|
| They effectively had a commercial life of 35-40 years, and went
| thru 2-3 generations of technology, some of them were even
| upgraded to digital.
| weird-eye-issue wrote:
| Just wait until you hear about smartphones
| nine_k wrote:
| Less of a joke than one might think. The GSM / 2G / 3G / 4G /
| 5G transition took less than 30 years, each step involved
| scrapping some of the old incapable hardware.
| retrac wrote:
| I think this fits the mood. The old telephone system was entirely
| analogue. It remained so well into the 1980s, even when they were
| carrying tens of thousands of conversations in parallel on a
| single wire or antenna.
|
| When I was a kid, you could hear the white noise stack
| successively louder on a long-distance call, as it went through
| each additional link. And sometimes you could hear the hum of it
| all, just below the threshold of intelligibility. In hindsight
| it's amazing how well it all worked.
|
| But sometimes it didn't work so well:
| https://vocaroo.com/1oCxkWyNDusp
|
| Maybe a filter was slightly out of tune on that day. Recorded
| mid-1970s New York. The electronic beeps are in-band call
| establishment tones. (Yes, the same ones phone phreaks exploited.
| The recording was in fact made by one of those phreaks who has
| gone back and narrated some of his old recordings
| http://www.evan-doorbell.com/ )
| [deleted]
| jibcage wrote:
| "Hello? Yes, a collect call for Mrs. Floyd from Mister Floyd
|
| Will you accept the charges from United States?"
|
| I always wondered what those beeping tones were in the
| recording at the end of that song ("Young Lust"). I guess I'm
| not old enough :)
| TedDoesntTalk wrote:
| Those are in-band signals to the switching equipment. The
| equipment would "hear" those tones and translate them into
| "machine instructions". That's why phreakers could exploit
| the system by generating those tones themselves and playing
| them into the phone microphone.
| jeffrallen wrote:
| That's why you do not control networks with signals on the
| network itself.
|
| See also: Facebook's recent outage.
| TedDoesntTalk wrote:
| Right. But those were different times. And the bandwidth
| of analog lines was something like 4 kHz with no control
| channels.
| packetslave wrote:
| > That's why you do not control networks with signals on
| the network itself.
|
| Other than, you know, the entire Internet (BGP) and
| pretty much every corporate WAN (OSPF, EIGRP, RIP) and
| LAN (spanning tree, ARP).
|
| Having an out-of-band control plane is very much the
| exception. Now OOB _emergency_ access, on the other
| hand...
|
| _edit_ okay, SS7 is out-of-band, but parent was talking
| about IP networks.
| TedDoesntTalk wrote:
| I don't know about that. Even the ancient FTP protocol
| has a separate control channel/port.
| [deleted]
| tenebrisalietum wrote:
| T1s are not analog and they were either invented or starting to
| be deployed in 1962.
| riffic wrote:
| there were previous systems in place before T-carrier:
|
| https://en.wikipedia.org/wiki/Carrier_system
|
| https://en.wikipedia.org/wiki/L-carrier
|
| http://long-lines.net/tech-equip/misc/J-Carrier.html
| TedDoesntTalk wrote:
| > But sometimes it didn't work so well:
| https://vocaroo.com/1oCxkWyNDusp
|
| Huh. I never heard that in the 70s and 80s. Cool.
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