41–50 of 143 posts
I remember us getting our first modeum, it was 800 baud! Then we moved to 2400, 14.4, 33.6 and eventually all the way to 56k.
Earlier quoted context omitted.
I'm still mad that they high-quality voice audio possible through ISDN didn't become ubiquitous. It's ridiculous to hear the clipped frequency range of a plain old telephone line during radio interviews in 2025.
24 [bit] * 192 [kHz] = 4.608 [Mbps]. Maybe not sensible to do so, but many people could have Discord calls in uncompressed "high-res" WAV. It's crazy that there aren't even 16bit/44.1k modes in most voice call apps.
The big issue with analogue landline phone calls is the audio bandwidth is so limited. It's not the full frequency spectrum, most of it it cut off.
Yup. I worked on the "Rapport" series of switches at Bell Canada. It was DS1 (Digital Signal 1) out one end and a rack full of Zyxel modems on the other side. The idea was RBOCs (Regional Bell Operating Companies) would put these in their CO (Central Office) and terminate 56k modem signals over the analog "last mile" loop to the customer premises and then do Frame Relay over the phone company's data lines to your ISP…
Revealing my ignorance here, but was (is?) there a telephone equivalent of anycast such that, say, the 1-800-... Or 1-900... numbers would be routed differently based on location? My basic knowledge of phone systems suggests it would at least be possible.
https://en.wikipedia.org/wiki/Toll-free_telephone_numbers_in....
DS0 is not encoding. It's (pseudo) framing.
> phone calls became digital with
The G.711 encoding in either aLaw or muLaw format.
I have to wonder if the cap (theoretical) on the copper wires was more because of the technology standards in play at the time. Surely the copper wires could have handled more if they did not have to carry voice communication (with the old tech specs of the time) any longer? Ok. Searched around. Here is an article that states old copper could have carried 1 gigabit. https://www.newscientist.com/article/2317040-ordina…
The very first part of a dialup modem sound? Where it's playing a tone that reverses phase at regular intervals? That tone is actually designed to disable all the repeaters and echo cancelers that are in your switched circuit.
Also two parallel phone lines are prone to capacitive coupling. I had a case so bad once that one office could pick up the phone and nearly perfectly couple onto their neighbors line and hear all their conversations. It was a 50/50 which port on the PBX recognized the tones and started the call when either of them picked up to dial out.
Yes these modems were almost-ISDN (minus the razor fast call setup). And required a full digital backend to work. They could only do 56k6 in one direction, to the user too. But they were made for internet access so that didn't really matter.
I remember my brothers friend in rural Portugal having one way satellite Internet back in the 90s to very early 00s - you used a standard dial up for the upstream, but with a satellite dish got much much faster downloads. Blew my mind that you could go out one way and receive another and still get a functioning (and fast) connection.
Yup. I worked on the "Rapport" series of switches at Bell Canada. It was DS1 (Digital Signal 1) out one end and a rack full of Zyxel modems on the other side. The idea was RBOCs (Regional Bell Operating Companies) would put these in their CO (Central Office) and terminate 56k modem signals over the analog "last mile" loop to the customer premises and then do Frame Relay over the phone company's data lines to your ISP…
Why use real physical modems when you already have subscribers signals converted to convenient digital form in DS1 bundle? Wouldnt it make more sense to put a box with one fat DSP doing 24 modems all in bulk inside a box with DS1 and Ethernet sockets at the ISP location instead?
Earlier quoted context omitted.
Exactly. More specifically, Internet servers in data centers connected themselves to the IP network, not the phone network (not surprisingly), so they almost always had an uplink significantly faster than 56 Kb/s. And the analog local loop had encodings that could transmit at 56 Kb/s. But these encodings were not compatible with the analog-digital conversion used in phone network backbone. While today you'd probably…
All the early metropolitan or long-haul fiber (mostly SONET) networks were digital aggregations of various circuit-modes (DS*) in those days. It made sense since the phone network was pretty much the only long haul network around and even the pure-IP networks didn't yet have enough of a market for alternative protocols. I've been out of the core-networking loop for awhile, but my understanding is that most modern lon…
I have to wonder if the cap (theoretical) on the copper wires was more because of the technology standards in play at the time. Surely the copper wires could have handled more if they did not have to carry voice communication (with the old tech specs of the time) any longer? Ok. Searched around. Here is an article that states old copper could have carried 1 gigabit. https://www.newscientist.com/article/2317040-ordina…
I have to wonder if the cap (theoretical) on the copper wires was more because of the technology standards in play at the time. Surely the copper wires could have handled more if they did not have to carry voice communication (with the old tech specs of the time) any longer? Ok. Searched around. Here is an article that states old copper could have carried 1 gigabit. https://www.newscientist.com/article/2317040-ordina…
Of course ancient telephone wiring can carry 1 Gbps. The real question you always, always, always, need to be asking yourself is: Over what distance? Make that distance short enough, as has happened with FTTN, or FTTC deployments in a whole heap of places, you're basically building a network that's, and I'll keep this very brief, subpar. Since you mentioned a UK context there, Openreach rolled out an upgrade that kep…
In other words, instead of losing 99.7% of the signal over that distance, it'll only lose 99% of the signal. Sure, it helps, but consider me underwhelmed.