Strowger: Dialup over a 1950s phone exchange?

Рет қаралды 15,740

2 жыл бұрын

Dialup modems should work ok over a strowger phone exchange, right? And dial up sounds amazing, right?
We should find out!!!
Technical nonsense:
* The modems are pinned to 9600 which is the fastest I could get this to work reliably enough to film. They will work at higher rates on a good day, but there's a lot of noise to contend with and I only had 30 minutes to shoot this.
* No, they won't run at 56K in this configuration, for "reasons"
* At the raspberry pi end, I'm running agetty in a docker container, which was a right fiddly bit of nonsense to stand up - details are here: github.com/paulseward/docker-...
* The telephone exchange was built in 1957 by AT&E of Liverpool, England, and is electrically identical to a design they first introduced in 1936.
* I could have used my exchange from 1937 but the sockets weren't in a convenient place
If you've read this far, leave a comment so I know I'm not the only one who reads descriptions on shorts!

Пікірлер: 30

@dracenmarx 10 ай бұрын

That was a very quick handshake

@lpbkdotnet 10 ай бұрын

I think I told the receiving end it could only support 28k (as I was having problems above that, which I’ve since solved) which presumably cut down the handshake time a smidge. But apart from that, there’s no video trickery or anything.

@kreuner11 5 ай бұрын

@@lpbkdotnetit also became shorter thanks to the fact the path between the two modems is very short and it doesn't need to calibrate as much for a good connection

@valthenvega2434 2 ай бұрын

Maybe the internet connection was a bit introverted 😅

@JTRipper420 Ай бұрын

That’s what I was thinking.

@LOOKMUMNOCOMPUTER 2 жыл бұрын

awesome!

@kreuner11 2 ай бұрын

Probably happened at many points during the peak of dial-up internet

@lpbkdotnet 2 ай бұрын

There's possibly not as much overlap as you might think! Peak dialup usage in the UK was in the mid-late 1990s, I didn't know many people with dialup at home until about 1997... but the last strowger exchange in the UK was removed from service in 1995ish So although dialup was around at the same time as strowger, it wasn't really at it's peak until after this technology was fully gone from the UK network.

@zPxffxn 7 ай бұрын

Absolutely underrated video, so cool!!

@stevenpavelish6017 7 ай бұрын

Dialup is awesome!

@yvr2002rtw 2 жыл бұрын

How about using a DSLAM on the Strowger exchange to provide DSL service to both ends?

@lpbkdotnet 2 жыл бұрын

Fun idea!

@mattyinnit9009 10 ай бұрын

@@lpbkdotnet You should do it if you find a DSLAM!

@Nathan10731 Жыл бұрын

analogy

@ds99 Жыл бұрын

That is really cool.

@l1nkz100 Жыл бұрын

Super cool

@sefa8626 7 ай бұрын

That sound, after you said “the modem answers” where’s it coming from?

@lpbkdotnet 7 ай бұрын

That’s the modems handshaking to negotiate speed/encoding etc

@212MPH 7 ай бұрын

V32 modem ? What terminal emulator are you using ? And what cable are you using as the v24 port on the modem?

@lpbkdotnet 7 ай бұрын

I can’t honestly remember what speed they synced at, but you can probably work that out by looking at what that pair of modems support, and there are probably also clues on screen about what speed they synced at. Terminal emulator on the laptop was just the standard macos terminal, probably running either screen or minicom (I can’t remember!) again you can probably tell from the screen layout. The usb-serial cables at both ends are just generic no-name ones. Most likely prolific chipsets (or prolific clones) Hope that helps

@lpbkdotnet 7 ай бұрын

Just rewatched it and paused the video for you. Synced as V.34 at 9600, I used screen to connect to the modem

@STABO700 Жыл бұрын

do you said post dialing or POTS dialing?

@lpbkdotnet Жыл бұрын

Neither. “Pulse dialling” There are subtitles if that’s helpful to you?

@STABO700 Жыл бұрын

@@lpbkdotnet thx, I have another question, let's assume we have a source phone number 1234 and a receiver phone number 5678, when I pick up the handset the SLC detects the current, the line finder starts, then the connection is connected to the group relay and then to the final relay, the question is what if this time telephone 5678 will call telephone 1234, will the final relay work as a line finder? what should a simple block diagram of the strowger system for establishing a connection in both directions look like?

@lpbkdotnet Жыл бұрын

@@STABO700 if the second phone picks up before the first has finished dialling, it will activate a linefinder of its own, and then the first phone finishes dialling - the caller will get busy tone, because the second line is already on a call. KZfaq comments are a bit limited for describing strowger systems in full, but there's a really good introduction on dfrtelecoms.org.uk/tmainmen.htm - read the pages listed under "Basic Telecoms Information Pages"