PBX Phones - Without a PBX?
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- Опубліковано 14 лис 2019
- These phones promise PBX-style features: intercom, paging, conferencing - without a PBX. How is that possible? A clever way to improve very old technology by applying even older technology!
More info on my research into these can be found here: gekk.info/articles/ksuless.html
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I like how the first phone was drawn really detailed and a bit artistic, the second one was drawn ok and the consequent phones where just car batteries with a whip
I DONT KNOW WHAT HAPPENED I JUST COULDNT ANYMORE
Hieroglyphics becoming normal alphabetic glyphs
Agreed 👍..
U
I think you meant subsequent.
I laughed out loud when the cat notepad slid into frame hahah
Me too!
Tha was hilarious
the cat notepad sliding into frame every time with the 70’s western electric desk phone progressively becoming what i could only see as car batteries with handsets was great
All the way through the video I was thinking "oh, dude, this really needs an oscilloscope" and then wondering whether I could use my cheapo mini-oscilloscope to explore similar stuff I had round the house. Then you pulled out the oscilloscope and I practically cheered. I loved this video, thank you. Another person brought here by Alec from Tech Connectifadoodledoo
Did Alec call it that at some point?!
No, I'm pretty sure that came out of my own head for some reason@@Heizenberg32
This is some whipass staging with those monitors dude, nice vid
thanks!!
Yeah, that caught my eye (and would any day) before a beige PBX phone. :)
RIGHT?! i want 1 of those now!
Thank you tech connections for introducing me to this wonderful channel
Same. What wonderful content.
the rackmount multicam is a great way to make a video look like more than just talkin at a camera
thank you! i'm glad you liked it, it was a last-second idea that i intend to refine. i think it's a nice twist on the bigclive style of "bench demo"
@@CathodeRayDude Shout out to the legandary Big Clive!...
Pretty clever. I feel like a lot of pre-2000 stuff was a lot more innovative because there were more limitations.
The same is generally true of computer code, as the further back one looks the more limitations existed, forcing quality code and clever ways of working around problems.
@@Jupiter__001_ I'd say the ingenuity shifts over time. We have fewer limitations and performance concerns in most code today because of the innovations that have made processors so much faster than in the past.
At the same time, the things we're building are so much bigger and more numerous that we don't have time to make every single piece of code as efficient as possible when we can offset that effort to someone else by buying their faster hardware.
For the same reason we use frameworks and high-level programming: we offload the complexity of doing generic things to someone else, and then their generic abstraction can be used in many different applications. There is generally a bit of efficiency loss because no generic abstraction ever fits our specific application, but the savings from reusing the abstraction across many applications more than makes up for that loss overall.
TL;DR: in most cases, a faster processor is cheaper than X days of programmer salary, and a good programmer costs more than a bad one.
It's because all of those engineers went outside and played when they were children.
@@TheNewTimeNetwork A generalization: An energy "sink" expands to use the capabilities of an energy source.
I died from laughter when the cat came in I was like what the heck is going on. I love it lmaooo
Gibs
@@flatulentweirdo ît up uuuuuoo POP uuuuuuu
You laughed your ass off off off?
Having worked on Nortel systems for a decade in a previous life, I was more excited than I should have been to see you pull out that old NorStar/Meridian Key System. Great video!
The signal on the scope looks more like a SSB modulated signal than AM modulated. Which makes sense: the FDM will just move the spectrum of the 0-3kHz range to some other area, say 400-403kHz. This modulation is hard to 'see' it in the time domain, i.e. by just looking at the waveform (unlike AM). If your scope has a FFT/spectrum analyzer, you can look in the frequency domain and see what the output is. If you put a 1kHz signal in, and you get a spike at at 401kHz, you know the carrier is 400kHz, and it is modulated as SSB (upper side band). If you get two spikes, one at 401kHz and another at 399kHz, it is AM modulated (then there is a host of other modulations possible of course. It could even be that they all digitize it internally and then send over some DSL-like digital modulation between phones, the technology for that kind of stuff was definitely there in the early 90ies).
Good video! I just wanted to clarify some things for people who may watch this video.
The Nortel Meridian PBX, and most other PBXs (not all) use a concept called Digital telephones. Digital phones aren't analog and they aren't IP.
They use a specific system of multiplexed digital signals and digitized audio. It uses a standard called ISDN, although almost every PBX uses different communication protocols, they all seem to use the same ISDN standard. Plugging an analog phone into a Meridian PBX, you will just hear a high pitched whine and that's it. Those PBXs do have analog stations, but when someone refers to a Nortel PBX (or almost any other PBX), they usually use a digital telephone.
One more thing, which you briefly pointed out is what a KSU (Key System Unit) is.
A KSU is not a PBX, a PBX allows you to transfer calls, do paging, and have system applications (like extensions that don't go to a physical device).
A KSU is a device that allows multiple telephones to share multiple phone lines. It also does intra-office calling, and on-hold, but it isn't a PBX.
Again, great video, but for the more technical viewers, I just felt like I needed to point this out!
I really enjoyed this video. You cover some rarely talked about, yet well known technology. And you have perfected the mix of "show" and "tell". I know how AM radio works but you didn't bore me with the explanation (and yeah, that's what the phones are using). I love how you brought out the oscilloscope, there's really something about witnessing the actual waveforms that makes signals "click". I know this is a year old video, but I hope you keep making more like this.
Thank you so much! My EE experience is limited so I can only do this with some things, but I give it the full treatment whenever I can.
I never comment on videos but I'm going to bite the bullet and do it. Amazing video(s)! I love how you cover all these old technologies. What people take for granted now, cell phones, don't understand that these older technologies really paved the way for our technological advancements that we see today. Growing up as a kid, phones, TVs, and camcorders, where all like black magic to me. Seeing how you explain things, causes the light bulb to go on. Keep it up!
OMG, everything I ever learned in 30 yrs of telecommunications! Excellent presentation!
Love Gibbs. He deserves his own channel
These things were rather uncommon in European countries. ISDN was heavily subsidized by the phone companies in the mid 90s. Businesses had usually a cheap or free 2 line, 8 telephone ISDN PBX in the back office. Since digital ISDN phones were expensive, mostly cheap analog phones were used. Most of the ISDN PBXes had a certain number of D/A-converters for legacy phones and fax machines. However, the concept of having a cheap analog intercom system with multiple carrier frequencies operating on a single pair of wires is amazing.
"Master phoneset" is when you have a "master phone" and a bunch of "slave phones" that connect to the master phone to ask for an outside line. The phones have to be matched with each other. This was common with cordless phones for a long time. All of the extra phones simply relayed back to the main master phone, and their bases were 'dumb' providing basically only charging.
Yup, we had a cordless phone like that in the 2000s with 3 handsets. One handset usually sat in the base station, while the other two sat in two chargers elsewhere in the house. The handsets could intercom too, sort-of: you couldn't call them individually, but you could page both the others from any one with the "intercom" button, and then talk over it like any 2 phones on a shared landline.
(The main base station also had a 3-mailbox answering machine. Press 1 or just wait for the beep to leave a message in box 1, or press 2 or 3 to leave it in box 2 or 3.)
@@fungo6631 They all were probably beige or black.
Still loving these videos! Really good presentation, explanation, and pacing. Also, big props for trying out different style stuff like this CRT array setup.
Those are LCD
Those need a video. And if there is a video, this lazy slob needs a link :D
when that alvin lucier slid up into the frame i knew you were my favorite
Your channel will blow up 1 day, just keep on keeping on, and remember me when you sre at 1mil subs
Man, i hope it will be more than just 1 day :P
The algorithm blessed me with these videos!
First off, I am an old phone geek from Europe, so not familiar with the US systems ;)
These RCA phones are probably using analogue AM, or QAM with the phones sending over A/u-Law PCM audio.
I think the signaling is digital already, so it would make sense for them to send the audio digitally as well as A/D and D/A converters were already dirt cheap, and it would solve interference between the AM carriers when you had a line reflecting signals somewhere in your system.
We had phones from the Dutch telco KPN Telecom back in the days that offered features like these as well, made by Siemens. And as I was able to look at the schematics of them working for Siemens, those were using digital QAM modulation and A-law PCM for internal phone calls.
Best channel on UA-cam. I found you a couple weeks back and I’ve been binge watching your content any chance I have. The way you slid that notepad onto the screen reenforced my approval of this channel 😂 thanks man!
Does your scope have an fft feature? (Usually under the math menu) It plots the breakdown of a signal by frequency and could be a good way to visualise some of the signals you showed more clearly
I'm a phone nerd that's been searching for such a device for 20 plus years, and this is the first time I'd ever heard of it. lol. Thank you!
Do you know why there called tip and ring? Because of the old style plugs used in switchboards which were wired with the “hot” connected to the tip of the plug and the ground to the “ring” of the plug.
Yup! I'm actually friends with a bunch of the volunteers at the phone museum up here in Seattle, and my dad worked for Bell back in the 60s and used to lecture me on how the tech worked, so I have a bunch of telco knowledge, I just try not to go off on it in too much depth, heh!
@@CathodeRayDude As far as I´m concerned, you can lay it on as fast as thick as you want lol 😁
@@CathodeRayDude my dude go into as much depth as you like. i can't speak for everyone here but if the rest of your viewers are anything like me, we **thrive** on unnecessary detail and weird tangents
And those plugs are still in use today for headphones, guitar and speaker cables, audio patch cables, etc. Usually either tip/sleeve (TS) or tip/ring/sleeve (TRS).
@@JoshColletta Even some of the older graphing calculators from Texas Instruments used 2.5mm TRS connectors for communication to either a computer or another calculator. I have both a TI-85 and a TI-86 with this type of connector.
Those RCA phones are actually pretty good phones. I had them when i had my sporting goods store. For the price and ease of use they were great. I also had the cordless ones too you should explain how the cordless multiple line phones work too. I bet that will be fun lol
I love actual phones. For having a conversation from one fixed location to another, nothing beats them.
I am an "OG" phone phreaker, who had access to equipment in the 60's, 70's and 80's to play with (brother in law worked for Bell Systems, and later, Bell South), built POTS intercoms, mini PBXs and even a couple tiny patchboard controlled "hotel" networks.
There were three generations of the "overlay intercom" system designed to work with POTS "plain old telephone systems" and one was actually rented to small businesses by telephone companies like Bell Systems.
Note that I said "rented", not sold, as the telephone companies rented and powered all their equipment from the system before the Federal Government stepped in and broke up Ma Bell into all the Baby Bells. The first gen "simulated PBX" used the 3v DC talk circuit power with a voltage clipper to protect every thing from the 90v AC bell ringing power and used up to three carrier frequencies, allowing up to three parallel intercom functions at once.
The second (which I suspect your white INT phone is) only had one intercom channel (some locked out other stations from intercom and others created a party line, only ringing at the dialed station). Because of the issues with power consumption and frequency reflection on unshielded POTS copper wiring, they had lots of issues with weird and unexpected communications issues and acted like a very leaky transmitter, to the point that you could listen in on them with a decent radio receiver. The Baby Bells refused to power them, both due to the power consumption and because it was a cost they could no longer charge for, so 2nd gen didn't last long (ever wonder why telephones came out with "ringer equivalent" markings and "T/P switches"; Ma Bell was pissed about having to upgrade power supplies and add DTMF decoders, so they pushed back on the Feds!).
3rd gen was more similar to the black pair you tested, were almost always powered by "wall wart" power supplies and could have multiple higher frequency carriers for parallel intercom conversations, could have Frequency Modulated signaling and intercom channels (no static and little interference between the phone lines, DSL data and the data/talk on the intercom lines. The problem was the expense and some special wiring requirements for the higher end systems, requiring small and medium businesses to retrofit their aging phone wires inside the building, even requiring removal of old, mechanical PBX modules, making the retrofit cost ridiculous, but for their day, 3rd gen could do tricks that would make a show pony jealous! Too bad, this was right before the digital revolution ate it's lunch.
All three were very cool, considering how simple the electronics were and the functionality.
Is there somewhere that I could see this stuff drawn out on paper so I could study it,also I have replayed to several channel programs with q uestions but I never get any responce back,where.do you see answers to your questions?
Back in the 90's we had a panasonic version of this in our house. I had gotten a similar panasonic system from a business that closed, and it was the type with the key system unit. I mounted it in the basement, wired in all the phones and had a pbx in our house. Fast forward a year or two and our phone line took a lightning hit. Fried the KSU, and it was no longer available (no ebay in those days), so insurance bought us the newer version of the same system which had no KSU and worked exactly like these. I'm a huge phone nerd, have been since I was a little kid. We had that Panasonic Easa-phone system well into the 2000's. Now I have an asterisk system which takes VOIP trunks and ties them to some T1 channel banks giving me, oh... about 200 lines. I have a huge assortment of classic and antique phones connected to the system and they can all call each other as well as calling out to the real world. For my daily use I have an Avaya system connected to the asterisk system. I'm such a nerd.
I used to have an Easa-Phone too! I loved the unit itself but the phones didn't do it for me as much as Nortels. I've since gotten out of phone stuff for the most part, I just still know all the stuff I knew.
@@CathodeRayDude I never really got into Nortel, though they are darn good. I had an Avaya ACS given to me, and I fell in love. I started with an R6 and I’ve since moved to an R8 which supports caller ID to single line phones attached to station ports. It’s stupid easy to program and it does soooooo much. A friend of mine, Nill the cat has a real thing for Nortel systems. He was recently on an episode of Tosh.0 and at the end there’s a little shout out that I’m mostly sure is about me. If you’re curious, I have some very basic videos up showing some of my stuff. I need to make new videos, just haven’t had the time lately.
And this is why I love old limited technology. You had to be so creative to the useful stuff. The best of problems solving.
i've said it before, but i'll say it again: i just love learning from you.
This was fantastic, man. I picked you up on the front page of my algorithm, so I hope that's going to happen to you a lot more!
I’m glad to finally see how those RCA phones work. I had picked up a couple from electronics recycling a few years ago but never ended up finding the 12V AC power supplies they needed. Both way cooler and more mundane than I thought!
Oh man I just love all this kind of nerdy down-to-details stuff you put out :) the better kind of content in UA-cam hands down.
2021 and I'm watching this - really great content and easy to follow and understand. Makes you understand so many things specially when you don't grow up with that much tech around. Thanks for this content!
Also dude. You're so cool. The way you commentate these videos makes this interesting topic very easy to understand. This is awesome!
The sound of human voice over telephony is such a specific node of nostalgia for me. These days - for all the reasons - the sound quality over any phone call hovers right around nearly-unintelligible garbage. But hearing the clarity in your voice recorded through the headset of those old phones brought back a wave of memories. My first significant relationships in my teens were long distance, conducted through hand-written letters and hours-long telephone calls. Add to that so many nights laying in bed or driving alone listening to the radio, where you could always find a strange/sad/mysterious/funny/spooky call-in show, and hear the voice of some stranger telling their story in those crunched-yet-clear tones. And speaking of radio, all those hours of Joe Frank where he featured partially-improvised conversations with friends and actors over the phone, or played the voice mails he received as part of the program.
In my 20s I even spent time training my hearing on DTMF tones to be able to detect a given number by sound (with mixed success).
Come to think of it (this has brought back a lot of memories), I even kept a database everywhere I went of any payphone I found, and whether or not it received calls.
I just love landlines. What a blast from the past.
as i was watching this, i thought - "wait, the phones i use at work seem to do this no problem, i guess its just not an issue anymore and we dont need this technology" -- then you just pulled out the *exact same* phones in my office and i was pleasantly surprised lol
Hi from the UK, excellent description and really interesting. One new subscriber earned!
had a hard year, your vids have helped me get thru it tysm for all you do i love all your vids!
Love this channel Dude, can't wait to see it blow up!
Thanks for the great video. I was looking for a way to incorporate office phones into an isolated (no phone line) comms system at my church for communicating between backstage, sound booth, livestream room, etc as we can't wear headsets and mix at the same time, and this looks like just the ticket. I just bought 4 near-new AT&T 1040 phones with all accessories off ebay for $72 shipped to mock up and test out and this video was a great overview of how they work together :)
That is super neat, I have a few multi line phones that had the intercom feature and I never could understand how it worked on only one line. Very neat demonstration!
This is what got me into pbx's and networking shortly after.....it was crazy interesting to me as a kid and I remember having to save up a lot for a used scope to look at it. Still interesting now! Your awesome for showing this
Great video on a topic I'll never need to know anything about, but I'm happy I watched it. You deserve more views.
Fantastic video! I had so much fun watching this. I used to have two AT&T branded phones very similar to the RCA phones hooked up to my POTS line. Used the intercom feature a lot, until I got into VOIP and had my 2 ext. turn into an 8 ext FreePBX system.
Recently found your channel. I love your videos man. I've learned alot watching you. Thank you for sharing your passion.
Man. I would love to hear about more Telco stuff, I follow Evan Doorbell on his phone adventures and I find the telephone absolutely fascinating. I love the videos that the folks over at the connections museum put out. Anything Ma Bell is cool though.
This was a great video! Love watching strange finds explored!
I wish I had discovered this channel earlier. Killer content! Subbed 👍
I always wanted to know this and have it demonstrated since I was a child. Thank you!
"besides it being the weed number" omg my sides lmao good shit
This video confirmed my theory of this pbx-less phone systems. I saw them as a child and always wondered where the pbx was hidden but there actually was no pbx.
Just subscribed.. a phone enthusiast from Ecuador here!
Just wanted to say you do a great job with the videos. No doubt in my mind that if you keep making them you will start making the algorithm like you lol . Hooked me with the NES Tv station and as i explored your videos, Im really enjoying the content
Glad you're making videos again Gravis!
Really interesting to see how laws & regulations influence technology. Here in Germany, directly connecting more than one phone to an (analogue) phone line has always been illegal. Of course there was demand for multiple phones in businesses and larger homes, so a thriving market for small, affordable PBXs developed pretty early. Around 1990, my parents got a PBX for 4 phones and 1 outside phone line. A few years later, we upgraded to a larger one which connected a bunch of phones, a fax machine and a door intercom to an ISDN line. This was nothing fancy at all, many families and most small businesses had this.
Worked in the industry for years. I remember when this technology came out and it was cost-effective solution for giving you features like a PBX or a key phone system. However some of them were difficult to set up and would sometimes lose their settings.
As a note tip and ring reference to the operator consoles with the photo plugs. The wire that is the tip refers to the tip of the plug while the other wire refers to the ring of the phono plug.
I liked your description of how to waveforms can be added together. I remember learning about Fourier in math class as a kid and would definitely have appreciated the visualization. Thinking a little bit more about it, it's just how a single microphone diaphragm can record a band with very high frequency cymbals and very low frequency bass. You can then play it back on a single woofer that makes big movements for the bass and simultaneous little tiny movements for the cymbals.
Informative video and I like the visual styles used! :)
Bro, I hope you're an instructor you're so good and interesting to follow!
Found you because I watch LGR and technology connections and I'm glad that I watched
Great channel! Everyone in these comments is saying Tech Connections sent them, but I don't remember Alec mentioning this channel. Either way, Great Content!
I like your videos in general. I like your unpretentious style with a good sense of humour, and that you still keep the important parts serious. Keep 'em coming, please. :-)
I'm a System Test & VoIP Engineer and this video is not only PHENOMENAL but also extremely well said.
For some reason, there's something I love about the fact that you have a cat named Gibbs.
I absolutely DETEST those RCA garbage phones! I installed about 20/30 of them in a medical office at my bosses request. I thought it was odd that he spec'd out the RCA's instead of the default panasonic PBX. If i remember correctly, one of the features touted on the RCA was the mailbox feature, well after I did a dry run of the units, got familiar with their operation, wired them up, trimmed out the wire runs and set up the phones, we soon found out that the mailbox feature didn't really exist, the manual was super vague about it and they couldn't be upgraded via firmware. the phones were a nightmare to operate, RCA's customer service was total garbage and the phones weren't even made by them, just branded RCA. Everyone was confused on how to use them, I had to train every single employee on how to use them in a big akward group class. Finally after a month or so they were so fed up with the failed experiment they demanded we remove them and replace them with a real PBX system, which of course some other tech handled.
that's exactly the experience I expected, thank you for confirming
Wouldn't be a CRD video without Gibbs showing up - great work as usual dude.
shockingly, the video i uploaded today has *no gibbs!* I think it's the first one!
Oh man... We had one of those in my house. Loved the dial list on the side that you could program.
These are real cool. Great video as always. I wonder how poorly these phones would perform if used near any high-power broadcast AM transmitter. I can't imagine 600 feet of thin, unshielded phone cable would reject broadcast stations very well.
I like to imagine that there was a business somewhere that would occasionally "randomly" hear their local AM radio stations when making internal calls.
Fantastic video and great to learn something about old stuff.
You sir are amazing, I learned a lot about signals as an IT man this is actually useful information towards diagnosing issues - instant sub
Wonderful video, thanks for making it!
three
HUNDRED
megabytes
of hard drive capacity
it's like
three hundred huge
FILE cabinets
@@CathodeRayDude That's right.
@@CathodeRayDude I'm suspicious about that figure. 300 novels, okay. A novel is a few hundred kay to a meg of text. A page of text is around 4KB. Pretty sure even a single-drawer filing cabinet could hold more than 250 pages.
@@ggppjj
The biggest arena of computers today is in the CD-ROMs.
This video is so awesome. Thank you for being you and creating great videos.
Excellent new channel! Really enjoying it
I used to have a Panasonic version. It would handle 2 outside lines and 8 extensions along with caller id (this was the 2nd version, their first version didn't have caller id). It had all station page but could only handle one intercom path at a time and sounded great. Then, after a bunch of years, the electronics went bad and one by one, each phone started going crazy. They would randomly start creating their own intercom calls and had various glitches and I finally had to dump them.
Anyway, great video and explanation! I found it very interesting and very well explained. Thanks.
I'm glad I found your channel so I can binge more weird/obscure tech content lol
Northwestern Bell Telephone, one of the "Baby Bells", turned into USWest, bought by Qwest, bought by Centurylink. So many phone companies in the span of a lifetime.
Excellent content, thanks for putting this together
Bell phone definitely brings back the 90s to me. Great video
This is regular frequency multiplexing. This is what we used before time division multiplexing, you could carry thousands of phone calls on one single (very wideband) coaxial cable. When PCM was was introduced we still used frequency multiplexing, but then you could carry many more phone calls on the same coaxial cable.
These KTU-less phones have been around for a while from there start with AT&Ts comkey 16, I remember seeing these style that don't need special wiring since the 90s but the oldest model I can find easily is the AT&T 874 but i doubt that is anywhere near the first. These type of phones are so utilitarian and forgettable finding information on them is so hard.
thanks! the term I'd found was KSUless, but it took a ton of digging to dredge that up and I couldn't find out who did it first.I ended up opting to leave all those details out since I had no conclusive answers
That odd, husky fellow that's always trying to make Technological Connections in my brain sent me here. He posted some community doobelydo that mentioned your video. New subscriber. I used to do tech support for dial-up internet with Mindspring. In the age where the USR external 56K was only a dream. Back when a really good tech could re-install DUN over the phone as long as the I386 folder was valid or the customer had a Windows disk.
I had something similar back in the 90s. Can't remember brand or model though. It was actually from the mid 1980s and my parents had it for years before I was old enough to let me play with them so to speak. It used the phone line (green/red pair) as usual, but used the 2nd pair (yellow/black) as the "carrier" line. There was a separate, powered "brain" module that connected anywhere near a phone jack, and intercom units that you can plug a standard phone into, or combo units that had the phone built in. It was only good for a single phone line, but allowed for 10 extensions with intercom, music on hold (or on demand at any station), speakerphone, speed dial, and a few others that elude me because time.
I thought it was pretty cool system at the time.
New to the channel love it!
Ever since your Ryobi Teardown, I been going down the rabbit hole.
Subscribed because of cat.
Give Gibs a treat to reward him for your subscription.
Also, dude, phones are cool. Please make more phone videos.
Found you thanks to the algorithm. Absolutely subbing because I learned a ton from this video. Also, not to be over dramatic, but I would die for your cat.
Great video! I was always curious what trickery these used to communicate internally. I actually have one of those RCA phones, but only one so I've never tried the intercom features, lol.
A very innovative video...i learnt a lot 🌟
Excellent video!
A former coworker mentioned that his local computer club did use similar tech to build modems that transmitted data over power lines in the 1980's to share Sinclair spectrum games. It worked since they were on the same sub station. It felt like right up your alley for several reasons. :)
The 'master phoneset' most likely means you don't need a more advanced phoneset to have this system work. Most PBX (which I think stands for a public telephone exchange? don't know, I'm Dutch) in the Netherlands usually needed 1 phone that could utilise a few of the more advanced features offered by PBX-circuits, while the remaining phones could be very basic ones. This did have the drawback that one could only 'put someone through' to another phone on the PBX while the person the call was really intended for could not put the caller back to the first person who answered it and some didn't even allow reconnecting from the other phonejacks as well if you were the first person to answer the call.
Before VOIP became a thing in the Netherlands (and this probably applies to the US as well) and people still had modems to dial up to the internet, PBX-stations usually featured a failsafe: if power to the PBX would be lost, a relay would close, directly connecting the master phone to the landline. Thus, with a powercut, there would always be 1 phone in the house which you could use to call (for example) emergency services with (or familymembers/friends to tell there was a powercut, if you wanted to), provided that the exchange-building in you area would still have power (but, since I'm Dutch, this almost always was the case, no idea about the US ofcourse)
I cant explain why, but i have been working with all sorts of pbx's since 1990 and i still like to watch this video.
I have no idea why this was recommended to me, nor do I have any idea why this is so interesting
Very cool explanation. 10/10, would recommend letting this guy explain stuff again.
I work with electronic equipment, I've been in I.T. my whole life. I solder and build lifepo4 battery systems and have the technician level ham license. I have built drones from scratch.. yet the basics sometime really perplex me to the point that I wonder if I have a learning disability. I have learned more from your channel and the way that you explain things than any other source in my life. I kind of live by the mantra "the internet was a mistake," but this type of content makes me think otherwise. Thank you!
Came for the phones, was very happy with the cat suprise 🐈⬛