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GeneralRe: Only an Engineer... Pin
Jörgen Andersson8-Jul-20 8:07
professionalJörgen Andersson8-Jul-20 8:07 
GeneralRe: Only an Engineer... Pin
Daniel Pfeffer8-Jul-20 9:11
professionalDaniel Pfeffer8-Jul-20 9:11 
GeneralRe: Only an Engineer... Pin
kalberts8-Jul-20 9:59
kalberts8-Jul-20 9:59 
GeneralRe: Only an Engineer... Pin
englebart9-Jul-20 9:19
professionalenglebart9-Jul-20 9:19 
GeneralRe: Only an Engineer... Pin
musefan8-Jul-20 22:57
musefan8-Jul-20 22:57 
GeneralRe: Only an Engineer... Pin
kalberts9-Jul-20 0:42
kalberts9-Jul-20 0:42 
GeneralRe: Only an Engineer... Pin
Greg Utas9-Jul-20 0:57
professionalGreg Utas9-Jul-20 0:57 
GeneralRe: Only an Engineer... Pin
kalberts9-Jul-20 3:40
kalberts9-Jul-20 3:40 
I had an ISDN phone for about 20 years, and there never was a better phone system.

First: Sound quality was excellent, totally without distortion and noise. Now that I have an IP phone connection, there is a lot of distortion, and sometimes a lot of noise. I really don't know what creates the noise. The provider won't give me access to the digital signal; the only way I can get access to it is through a pre-WW2-style analog interface (with one extension: I can use a phone with DMTF, which was introduced later than WW2.)

Second: There is no delay. Not absolutely 0, but it is so short that we never talk over each other (which I experience as a big problem with IP telephony, Skype and Teams).

Third: Connection establishment is really fast. When Norway threw out all the old analog phone stuff and replaced it with an all-digital system, the target was to complete the setup in less than half a second for the majority of calls, with an upper limit of 1 sec, for national calls. (Event though Norway's area is no bigger than an average US state, the country is long and thin; two phone users may be 1700 km, more than 1000 miles, apart in linear distance.)

Fourth: With ISDN, I could run a phone answering machine in my PC, and I could record any conversation. All required software for this was delivered with the drivers for PC ISDN cards, but there were several alternatives, both free and commercial.

Fifth: I could hook up several phones to the same line, and they could be adressed individually by subaddressing, or by different "main" pone numbers (intended for accepting incoming POTS calls, where the caller didn't have any way to specify the subaddress). I had one main number for calling my PC, for data connection, and another main number (with subaddresses) for voice calls, all on the same line.

Sixth: On an analog phone line, even 28.8 kbps never managed to provide the stated speed (and benchmark tests of 33.6 kbps modems showed that they ususally provided lower throughput than the 28.8 ones - too much time was wasted on handling the errors and fallback to lower speeds every time the modem tried to speed up, but encountered noise). Even single-channel, 64 kbps, ISDN was three times as fast as the 28.8, and it was stable as rock. I visited one of the main switches with a class of college students; I was teaching communication protocols, and one of the students asked the telco guy about bit error rate. This telco guy answered bluntly: With fiberoptic connections and digital switches, you simply have no bit errors! (He said it with a smile, adding that bit errors are so extremely rare that it should be handled end-to-end, maybe even over the Transport layer.)

As you say: It wasn't marketed well. In particular the pricing: I have opened two different ISDN phones and seen that the electronics was a single chip, with a couple additional passive components - capacitors, resistors. Yet, over the entire ISDN age in Norway, the price dropped from about USD 200 to a little over USD 100 for the cheapest ones, while analog phones sold for USD 10-20. I cannot believe that this single chip really had a manufacturing cost of USD 200! ISDN vendors tried to make huge profits from marketing ISDN as super-advanced and complex and a zillion arguments why those fancy phones just couldn't be made cheaper. People didn't belive them. If ISDN phones had been sold at POTS prices, reflecting the real manufacturing costs, ISDN could have been a much greater success.

We went from 100% analog switches to 100% digital ones in two huge sweeps, about a year apart. The "Televerket" (today: Telenor) took up a loan from the National Treasury of almost USD 2 billion to finance this. But the investment lead to dramatically lower operational and maintenance costs; they could sell off quite a few buildings or cancel rental contracts, because the new equipment was at least an order of magnitude more compact. So they wanted to pay back the loan much faster than planned. This was not accepted - and that is how Telnor became a major satellite communications operator: They built up a huge cash reserve, and had to invest it somewhere, and bought their first satellite. It grew into a huge and highly profitable business, and still is today.

So ISDN was certainly not "rather expensive". It saved huge amounts of money. But there was marketing, again: Rather than going into satellites, Telenor could have used the savings to reduce ISDN prices drastically. Rather, they sold ISDN lines for 150% of POTS lines, arguing that since you get two lines, it really is a bargain... People didn't see it that way: Only rarely did they use two voice lines at the same time.

In the US, another mistake was made: In the name of "free market competition", the telcos did not provide one standardized socket where you could plug in your phone. Telcos were required to provide a line pair, and the customer had to buy his own line termination. This significantly raised the threshold for switching to ISDN, both for the hassle of having to find a suitable termination box (there were a couple of alternate signalling alternatives on the line pair, so you might end up buying the wrong type), and the economic cost of it. Furthermore: In the US variant of ISDN, the set of B channels was not treated as a pool allocated at need; they had a permanent association to different subscriber numbers. So even if channel 1 was free, while channel 2 was not, someone calling the number assigned to channel 2 would get a busy signal. In other aspects as well, the US ISDN implementation did not provide several significant benefits of ISDN.

Finally: ISDN evangelists failed completly in communicating that the "Basic Rate", aka 2B+D, was indended to be the very first entry point into a truly high speed, general network. As early as in 1988, the standards for 622 Mbps lines were beginning to take shape, and you had several intermediate levels. (Around 1993 I was the advisor for a student project setting up and configuing a small PC card for switching 8 trunk lines of 155 Mbps; if the line loads were perfectly balanced, it could process 1,24 Gbps of traffic on a single PC card.) But people - most of all: computer network people - got the idea that 64 kbps channels was the upper limit, and nothing but line switched, fixed bitrate channels would ever be offered by ISDN.

Oh well. Over the years, I have seen numerous great techologies being killed by inferior ones. ISDN is only one of those that really deserved a better fate. I don't think we can hope for any "revenge of the ISDN", but when we kill a technology, we really should be much more aware of its quality sides, and strive to bake at least some of those qualities into those winning the war. That we are not very good at (neither in military wars nor in computer technology wars).
GeneralThought of the Day Pin
OriginalGriff8-Jul-20 4:38
mveOriginalGriff8-Jul-20 4:38 
GeneralRe: Thought of the Day Pin
Mike Hankey8-Jul-20 4:51
mveMike Hankey8-Jul-20 4:51 
GeneralRe: Thought of the Day Pin
W Balboos, GHB8-Jul-20 5:05
W Balboos, GHB8-Jul-20 5:05 
GeneralRe: Thought of the Day Pin
Daniel Pfeffer8-Jul-20 9:10
professionalDaniel Pfeffer8-Jul-20 9:10 
GeneralRe: Thought of the Day Pin
GuyThiebaut8-Jul-20 21:54
professionalGuyThiebaut8-Jul-20 21:54 
GeneralSo They Wanted Training Certificates Pin
W Balboos, GHB8-Jul-20 4:09
W Balboos, GHB8-Jul-20 4:09 
GeneralRe: So They Wanted Training Certificates Pin
musefan8-Jul-20 4:17
musefan8-Jul-20 4:17 
GeneralRe: So They Wanted Training Certificates Pin
W Balboos, GHB8-Jul-20 4:22
W Balboos, GHB8-Jul-20 4:22 
GeneralRe: So They Wanted Training Certificates Pin
Kornfeld Eliyahu Peter8-Jul-20 4:23
professionalKornfeld Eliyahu Peter8-Jul-20 4:23 
GeneralRe: So They Wanted Training Certificates Pin
W Balboos, GHB8-Jul-20 5:07
W Balboos, GHB8-Jul-20 5:07 
GeneralRe: So They Wanted Training Certificates Pin
OriginalGriff8-Jul-20 4:36
mveOriginalGriff8-Jul-20 4:36 
GeneralRe: So They Wanted Training Certificates Pin
Kornfeld Eliyahu Peter8-Jul-20 4:21
professionalKornfeld Eliyahu Peter8-Jul-20 4:21 
JokeRe: So They Wanted Training Certificates Pin
W Balboos, GHB8-Jul-20 4:24
W Balboos, GHB8-Jul-20 4:24 
GeneralRe: So They Wanted Training Certificates Pin
Johnny J.8-Jul-20 4:31
professionalJohnny J.8-Jul-20 4:31 
GeneralRe: So They Wanted Training Certificates Pin
Sander Rossel8-Jul-20 4:34
professionalSander Rossel8-Jul-20 4:34 
QuestionLet's twist again Pin
RickZeeland8-Jul-20 2:51
mveRickZeeland8-Jul-20 2:51 
AnswerRe: Let's twist again Pin
Greg Utas8-Jul-20 2:57
professionalGreg Utas8-Jul-20 2:57 

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