ISDN's days are numbered: What should you do? [telecom]

I was talking to an old friend yesterday, and he told me that he's been working from home for a while now, and the conversation turned to ISDN phone service, which I recommend to anyone who can still obtain it.

This morning, while searching to find out which states, if any, still offer ISDN Basic Rate Interface (BRI) phone lines, I came across a story from 2016, which predicted that "BT" (I assume that's British Telecom) would discontinue "PSTN" service in 2025.

So, I have some questions:

  1. Which states still have tariffs for ISDN BRI lines?
  2. Which countries still use the technology?
  3. Is "BT" really going to turn off dial tones in 2025?

Curious people want to know!

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Reply to
Bill Horne
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Am Donnerstag, 19. Mai 2022, um 13:05:58 Uhr schrieb Bill Horne:

British Telecom at least says that:

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|We're moving all our customers from the old analogue public |switched telephone network (PSTN) to a fully digital network. We've |already started. We plan to have moved everyone over before |Openreach stop the PSTN (and ISDN) service in 2025.

Rather interesting - they still gave offers for ISDN on their website:

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They also seem to switch off the analog lines (PSTN).

In Germany, Deutsche Telekom already switched off ISDN. The old PSTN network has been replaced with ISDN equipment in the 90s and analog lines were only available from the switching system to the customer. They are still, but the backbone is IP-based and new contracts aren't possible.

I don't know how PSTN is currently handled in the UK.

***** Moderator's Note *****

I'm assuming that "the old PSTN network" means "the old analog central offices and tandem switches (e.g., Step-by-step or crossbar)," because I think of ISDN as a "link" protocol that is served via digital switches and tandems which carry the "Bearer" channels to their destination in digital form, without any A-to-D or D-to-A conversions. I think, at least in the U.S., that each Bearer channel is still assigned to a virtual-circuit switched connection during a phone call.

If I'm wrong, *please* post a correction!

Bill Horne Moderator

Reply to
Marco Moock

I see two very key take aways from BT's statement;

1) "old /analogue/ public switched network" -- I often see "analog" omitted and people just referring to the PSTN without qualification. 2) "and ISDN" -- Seeing as how ISDN is /digital/* it's nice to have it called out in addition to the /analog/ (part of) the PSTN. *Yes, I know that digital eventually depends on the analog domain.

I'm seeing effort to switch of analog lines and ISDN in a lot of places. Many places have a concerted push to eradicate POTS and / or ISDN. -- I'm using POTS in lieu of "analog PSTN".

I'm also seeing lack of effort / unwillingness to maintain POTS and / or ISDN more places.

I think that it's more than just Step-by-step and crossbar. I think it's better summarized by thinking about what's connected to the copper outside plant that xLECs can viably get rid of / stop maintaining. DSL being one of the last bastions that depends on at least /some/ copper last mile. Even that is being transitioned to fiber in many places.

TL;DR: My opinion is ... If it depends on copper last mile, it's probably on the chopping block. It's only a matter of how long before it gets chopped.

Reply to
Grant Taylor

I'm not entirely sure how to read this list, but AT&T keeps updating it. It seems they have a strong push to de-regulate and remove tariffs from as many regions as possible. It's been explained to me that some of these listings are "legacy" services, possible ISDN service.

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Reply to
Michael Trew

The acronym "ISDN" doesn't appear when I search that file, but almost all the references are to services defined in other places.

I hope some of the SME's who read this can provide both specifics and the reasons for the "services" being removed/discontinued.

Just as one example:

- - - - - - - - - - - - -

North Carolina

All services provided under the General Subscriber Services Tariff

All services provided under the Access Services Tariff

All services provided under the General Exchange Guidebook

All services provided under the Private Line Guidebook

All services provided under the Access Guidebook, except AT&T Switched Ethernet Service and AT&T Dedicated Ethernet Service found in Section E30

- - - - - - - - - - - - -

While we're at it, someone please explain to me how "Ethernet" can be considered a "switched" service - assuming that Winston Smitch hasn't amended the definition of the word yet.

Bill Horne

Reply to
Bill Horne

ISDN Basic Rate Interface (BRI) is generally no longer available in the US. Verizon and I think ATT long ago gave formal notice of discontinuance or grandfathering. Maybe Qwest, pre-Century, didn't bother, so it may still be on the books there. But few know how to provision it. Many of the switches that provided it (mainly 5ESS and DMS-100 in the US) no longer are in service. It was useful, especially for broadcasters doing remote feeds. It was better than a modem for Internet access, and that's what killed it as it was coming out in the early 1990s -- the Bells hated the Internet, which broke their locality-based business model, and while they couldn't attack modem users per se, they could at least attack the most obvious Internet user group, non-Centrex ISDN BRI users. Bell Atlantic l/k/a Verizon was also fanatical in those days about selling Centrex, and saw ISDN BRI as a tool for Centrex feature phones, but that was about it. That business has faded out too.

ISDN Primary Rate Interface (PRI), which runs over a DS-1 ("T1") channel, is still out there, though again its number are in decline. It is a very good trunk interface for PBX systems, and many different 1995-2010 vintage switching systems support it, as it handled the dial-up era's modem pools. But most newer systems use SIP trunks instead. PRI has higher quality of service than SIP/RTP/IP, but the industry has moved away from it, as the higher-volume IP services usually have a lower price tag.

Reply to
Fred Goldstein

[snip]

I'm going to have to descend from whatever foothold I used to have on Mount Olympus, and admit that I don't understand how you could "nail up" two bearer channels without disabling the ISDN line's capability to carry phone calls. Were the ISDN lines used only for data service, or could the Bearer channels be divorced while a phone call was in progress?

Reply to
Bill Horne

This is twice in one day that I've had to take a step downward from my place on Mount Olympus, and I fear I might turn into Sisyphus if I don't - pun intended - watch my step. ;-)

Why would the bells hate the Internet? To be sure, their business model was built around central offices which each served a rate center, but how could they have predicted and/or anticipated the development of VoIP? Did Mother Bell see /any/ data transmission method as a threat? Why?

The Baby Bells knew that Cellular was coming, and I'd bet they knew it would displace copper-served POTS within time we've had to see it happen. Still, I just don't remember the leaders of the Baby Bells as being such long-term thinkers. The Internet hasn't replaced their locality-based feeding trough: we still have and use phone numbers, and even if a cell call has to be routed using VoIP and/or SIP trunks, the savings in billing offered by "Free" long-distance would have more than offset the cost of adapting to new trunking paradigms.

I wonder why? What was so different between the business models of the

1990's and those of the 2020's that Centrex would no longer be a cost-saver for firms which chose to use it? Granted, the Coronavirus has caused a reexamination of work-at-home as a viable real-estate strategy, but I think the /time/ spent on dialing, connecting, and suffering with the shortcomings of cellular calls, like picket-fencing, fading, disconnecting, and - last but far from least - being easily tapped by anyone with an antenna ana a few items of listening equipment.

I'm afraid comparing IP-based telephony to ISDN PRI links is the ultimate race-to-the-bottom in voice communicaiton. As far as I can tell, the only thing that makes SIP or VoIP or /any/ Internet-based real-time service - don't forget streaming video - viable is a surplus of bandwidth which will, inevitably, decline as paid-prioritization methods and equpment take hold.

Bill, who is feeling old and out-of-step.

Reply to
Bill Horne

No per minute charges (other than what they could try to get for ISDN calls), no separations, no "value" pricing. It totally broke their business model. This was way before VoIP, they wanted data to pay by the minute too.

Phone switches have gotten a lot cheaper, wires haven't. Putting a PBX in the customer's office is a lot cheaper than running every extension back to the CO. I realize there were versions of Centrex that put the switch on the client's premises but now it's just an expensive telco managed PBX.

R's, John

Reply to
John Levine

First, my source was a VZ employee who accepted their buyout offer to reduce manpower, and left. Second, the charges he mentioned are the ongoing application software (called a "Generic") license fees on a

5ESS. The operating companies didn't just pay WECO to buy the hardware, they also had stiff ?monthly/yearly? license fees to use the 5ESS Generic that made them work.

The Bell's were welded to their "If only we can charge local calls by the minute, it would be great..." thinking.

They hated dialup, be it POTS or ISDN, because it shredded their predicted call durations, utilization of switch resources and interoffice trunkage.

People like me would make one 9c call, and leave it up. I had calls that would stay up for 999 hours before my router would drop the call when it reached 1000.

PLUS: Ma Bell had anticipated that CLEC-fed businesses would call LEC-served residences. Under Her insistence, the originating {C}LEC would pay the terminating {C}LEC compensation per minute.

But the ISP's, soon tired of dealing with LEC's unwilling/unable to make large dial-in modem pools function, switched to CLEC's who would help them. So instead of an income stream, it was a huge drain. Fred Goldstein can likely comment on the ensuing legal fights.

Centrex: I don't know if is less popular it is now than it was, but in the DC region, it was a major LEC income stream. The reason is only the tiniest USGovt agency fits into one building; most are spread out between many, often scattered between DC, MD & VA locations. Centrex gave them 4 or 5 digit calling between all their offices. Further, ISDN Centrex gave the boss a fancy feature phone with many buttons, vs. a POTS 2500 set.

Reply to
David

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