Path: utzoo!attcan!uunet!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!wuarchive!decwrl!hayes.fai.alaska.edu!accuvax.nwu.edu!nucsrl!telecom-request From: aspect!kevinc@uunet.uu.net (Kevin Collins) Newsgroups: comp.dcom.telecom Subject: Re: An Introduction to ISDN From the CERFnet News Message-ID: <12979@accuvax.nwu.edu> Date: 3 Oct 90 23:53:51 GMT Sender: news@accuvax.nwu.edu Organization: Aspect Telecommunications, San Jose, Ca Lines: 185 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 10, Issue 708, Message 2 of 8 In-Reply-To: article <12768@accuvax.nwu.edu>, by Dory Leifer, sent in by Jody Kravitz: The article was very informative, but it left out a few items that I spotted, so here goes ... First of all, the article mentioned Basic Rate Interface (BRI), which is the local connection between the CO (or PBX) and the end user. It did not mention, however, Primary Rate Interface (PRI), which is the LD connection between CO's. PRI (in the US) is 23 data (B) channels and 1 control (D) channel, with all channels, both B and D, running at 64Kb/second. PRI and BRI use the same call control messages (Q.931). [Article talks about Europeans and Japanese implementing ISDN standard] Yes, they are implementing the standard, but they are doing some things differently than US manufacturers. Case in point: ISDN PRI here is 23B+D, in Europe, China, and Japan(?) it's 30B+2D. There are even differences between MCI's implementation of PRI and AT&T's implementation. Oh well, typical standard :-). [Future bank credit card service example, service rep gets customer's info from calling number, bill appears on both the rep's screen and the customer's screen, etc.] The part concerning the service rep being able to access the customer's data from the calling number is possible NOW, with PRI ANI and a link between the bank's ACD and their computer. Both BRI and PRI would be needed for the entire example to work. The customer's billing data would go over BRI from the bank to the bank's CO, over PRI from CO to CO, and over BRI from the customer's CO to the customer's BRI device, where it would be displayed. [Lack of current broadband standard] The current version of the standard has provisions for using 6 PRI B-channels together (called an H0 channel, 384 Kb/sec) and using 24 B-channels together (H11 channel, 1.536 Mb/sec [this is AT&T's number, don't know why it's not 1.544Mb/sec]). AT&T offers a "Switched 384" service (the H0 channel), but I don't think they offer the H11 channel service yet. I don't know what services of this nature MCI or Sprint offers. Kevin Collins Aspect Telecommunications USENET: ...uunet!aspect!kevinc San Jose, CA ------------------------------ From: Julian Macassey Subject: Re: Question About "Point of Demarcation" Date: 3 Oct 90 17:19:22 GMT Organization: The Hole in the Wall Hollywood California U.S.A. In article <12849@accuvax.nwu.edu>, dgc@math.ucla.edu (David G. Cantor) writes: > In TELECOM Digest, V10, No. 693, Roger Clark refers to new FCC > regulations concerning inside wirng rules and, in particular, refers > to "the point of demarcation" between the telco's wiring and the > subscriber's wiring. > Does the FCC require that there be such a point of demarcation? I > live in GTE country and neither I, nor my neighbors, have such a > point. Does this point (which I assume is a modular jack and plug) > have to be accessible without entering the subscriber's premises, or > at least without passing through a locked gate or door? You, your neighbours and everyone in Southern California have had such a point for some years. In fact you may be paying $0.50 a month or so for "free" maintenance of your inside wiring - check your phone bill. This wiring you are paying to have maintained starts at your demarc'. The demarcation point which is the physical location where the telco responsibility for wire ends and yours begins. This is similar to the electric meter, everything after it is your wire and everything before it is Edison's wire. You can mess with your wire, you can't mess with Edison's wire. But, yes they meter your calls at the CO, not at your demarc point. The demarc is not always easy to get to. Especially if in a basement which is usually locked. To save the subscriber the grief of having to be home when the telco drops by, it is convenient to have an accessible demarc, but not essential. So where is your demarc point? In Southern California, it is usually in a little box on the wall of a house with an aerial wire leading to it. Inside the box is a device called a protector, it looks like two nuts and a ground wire, this is where the house wire connects to the telco "drop wire". Some houses have the demarc in the crawl space - many of these in West LA, Beverly Hills. Modern Demarc's are called Network Interfaces and besides the protectors they also have an RJ11 jack so that you can separate house wire from the drop so you can plug a phone in there to determine if your wire is bad or the telco circuit is bad. Apartment houses usually have all the demarcs in an easily accessible closet. Finding the right one for an apartment can sometimes be a challenge. Office buildings usually have them in the "telco closet", at least one on each floor. The demarcs are usually orange covered punch down blocks with the subscribers name on them, they are loosely referred to as the "RJ-21X". In those parts of the US that have real basements, the residential demarc is usually in the basement. Julian Macassey, n6are julian@bongo.info.com ucla-an!denwa!bongo!julian N6ARE@K6IYK (Packet Radio) n6are.ampr.org [44.16.0.81] voice (213) 653-4495 ------------------------------ Date: Wed, 3 Oct 90 13:20:45 edt From: Bob Goudreau Subject: Re: Which Came First? Reply-To: goudreau@dg-rtp.dg.com (Bob Goudreau) Organization: Data General Corporation, Research Triangle Park, NC In article <12879@accuvax.nwu.edu>, jwb@monu6.cc.monash.edu.au (Jim Breen) writes: > As I have heard it, the ISO standard for numeric keypads antedated the > CCITT recommendation. When CCITT "studied" the keypad layout, AT&T > representatives refused point-blank to compromise, and CCITT > (cravenly) gave in. Hmmm. So making AT&T switch to the 7-8-9 layout would have been mere "compromise", but having CCITT adopt the 1-2-3 layout (which was found to be superior in human factors experiments run by both AT&T and CCITT) was "cravenly" giving in. Odd, that. > All praise to those (few) PTTs which held out and adopted the ISO > version. Au contraire; all praise to those (many) PTTs which adopted the CCITT recommendation. Standardizing inferiority is certainly not progress. Bob Goudreau +1 919 248 6231 Data General Corporation 62 Alexander Drive goudreau@dg-rtp.dg.com Research Triangle Park, NC 27709 ...!mcnc!rti!xyzzy!goudreau USA ------------------------------ From: Rop Gonggrijp Subject: Re: Equivalents of 800/900/976/911 Numbers in the Netherlands Date: 3 Oct 90 18:18:39 GMT Organization: uvabick hansm@cs.kun.nl (Hans Mulder) writes: >In the Netherlands PTT Telecom has managed to confuse everybody by >creating a single new area code (06) containing the equivalents of >both 800 and 900 numbers. The Consumers' Association has demanded >that the toll numbers be changed into 07 numbers, but since all 07X >area codes are already in use, this is not possible. >There is no 06-[3589] blocking for residential customers. They do >provide 06-blocking for PBXs. This also blocks 06-11. No no, not true: on one of my residential phone-lines I have outgoing call blocking ONLY for 069 and 063. They even offer this service on old stepper-switches (by adding a piece of hardware between the switch and your wires). >Next time I'll tell you about the night when PTT Telecom intended to >demonstrate that 06 was also usable as the choke exchange and found >out the hard way that it was not. Oh yeah, I had fun that night waiting for a dialtone for up to twenty minutes! By the way: a lot of the numbers in the FREE series 06-022XXXX end up outside of Holland (like 06-0229111 for AT&T USADirect) and some of them route over lines with IN-BAND signalling systems. Have PHUN! Rop Gonggrijp (ropg@ooc.uva.nl) is also editor of Hack-Tic (hack/phreak mag.) Postbus 22953 (in DUTCH) 1100 DL AMSTERDAM tel: +31 20 6001480