Subject: uk.telecom FAQ (version 1.5) Newsgroups: uk.telecom,news.answers From: ccs@aber.ac.uk (Christopher Samuel) Date: Wed, 25 Aug 1993 08:07:29 GMT Archive-name: uk-telecom/faq Version: 1.5 Last-modified: Wed Mar 31 09:28:33 GMT 1993 NOTE: I sadly no longer have the free time to maintain this FAQ, and so if there are any kind volunteers out there willing to take it over, I would be more than happy to pass it on to them. Sorry! [This version supercedes posting ] Frequently Asked Questions for uk.telecom Compiled by Christopher Samuel (ccs@aber.ac.uk) [Compilers Notes are in square brackets (like this)] [Comments / Contributions welcomed with open arms :-) ] Disclaimer: This information has been culled from postings to uk.telecom, mail and occasionally from files of the comp.dcom.telecom archive. I give no guarantees of its accuracy etc.. I also reserve the right to edit postings for length and relevance. Thanks: My thanks to all those who participate in the uk.telecom newsgroup, and to all those who have taken the time to correct and comment on the BETA version of the FAQ. [Notation - + is a new question, ! is an altered question] Questions: 01: What is uk.telecom ? 02: Okay, so tell me this. How do phones work ? 03: Why do we need another digit in the phone numbers ? 04: Who owns this numbering space ? 05: Is there a way I can pulse-dial a digital exchange number and then tone dial from there? 06: I want to get a BT Chargecard, the problem seemed to be that you need to be a current customer (have a phone) to be able to get one. Is this so? If it is why is it so? 07: Can you use your subscription to Mercury in the same way as a Chargecard? I think I read that you are supposed to use it from only one phone. 08: I've heard someone mention about Mercury's 0500 service, what is it ? 09: Why can't I direct dial with my BT chargecard on Cellnet ? 10: Why is there no 0345 access to PSS Dialplus ? 11: Say I want to access my University computer from home, using an ISDN connection, in order to get fast terminal access and file transfer. What would the full installation & rental cost be, both for me and the University Computing Service? What would I need to connect a PC to a Sun over this ? 12: Is it possible to set up a three way call, then have one of the other guys introduce another caller.. ad infinitum? 13: What *are* these Network Services that people keep mentioning? Are they a BT version of teletext or something? Do you have to pay for them? 14: I use Network Services to bar incoming calls, but when the barring is in force, the dialtone is different, and hence my modem won't autodial. Is there a way round this? !15: When I called 175 from home there was a message telling me my phone number, then when I hung up I was called back and offered a mysterious menu. Anyone know how to work it? !16: Is Caller ID available in the UK ? 17: Can I get a fully itemised bill from BT ? 18: How can I phone American 1-800 (toll free) numbers from the UK ? 19: How do I dial a number with a mnemonic in it ? 20: Where can I get an old style BT phone box from ? 21: What is the Mercury beep, and can I get rid of it ? 22: What types of exchange are there, and which can be digital ? 23: What is the difference between a System X and System Y exchange ? 24: When I use call waiting, and I hear the second caller incoming beep, and press R to get the dialling tone so that I can press 2 to get to the new caller, nothing happens i.e. no dialling tone. +25: What do PSDN and ISDN mean ? +26: How do I stop my answering machine recording the "Please replace the handset & Try Again" message when someone hangs up without leaving a message ? +27: Why are my Telecom Gold charges higher than I was expecting ? +28: Who or what are AT&T Direct ? +29: What is known about PIN-less Mercury ? +30: How do I get a guarenteed non-satellite circuit to the USA ? +31: How do I order BT's full price list ? +32: Why does my pre-socket phone 'tinkle' in the night ? +33: How does the BT Chargecard system work ? !34: Where can I get further information from ? ---- Question 01: What is uk.telecom ? Answer: It's the uk's own little newsgroup to discuss all sorts of topics related to telecommunications in Britain, including (but not limited to) technical matters, pricing, STD codes, equipment, BT vs Mercury, Network Services (nee Star Services), ISDN services, modems, etc. You get the idea.. It was born in August 1991 to cater for the large amount of telecoms related traffic in uk.misc, as UK specific enquiries in the InterNet newsgroup comp.dcom.telecom tended to be swamped by the vast number of other articles. ---- Question 02: Okay, so tell me this. How do phones work ? Answer: A very good question, that one, and for the moment the only answer I can direct you to is the file how.phones.work in the comp.dcom.telecom archives at lcs.mit.edu [18.26.0.36]. It is US orientated, but some of the general principles remain the same. [A UK version of this file would be gratefully received] ---- Question 03: Why do we need another digit in the phone numbers ? Answer: The existing numbering scheme is mixed 8, 9, and 10 digits (in all cases including the initial "0" - which isn't really part of the number. Theoretically, the maximum number of numbers is 900 million, excluding 00XX codes because by CCITT convention you can't have the same digit as the first digit of the NDC (National Destination Code, that's the STD code without the "0") as you have as national trunk prefix. 01XX has been cleared (solely to make the code change possible) and this reduces the total number of possible numbers to 800 million. Where the numbers are used for geographic areas, and users are offered the option to dial those numbers without a trunk code, then 201,000 numbers in each group of 1,000,000 become unusable. But other number ranges, such as cellnet, freefone, paging services and premium rate numbers are not limited in this way. So the real "supply" of numbers in the UK is about 650 million. Experience shows that allowing for the continuing process of number changing, and the fact that there will always be some numbers that cannot be allocated, about 60% of the supply can be utilised at any one time. This means that the present scheme restricts us to using no more than 400 million numbers at any one time. In fact the UK (plus the Channel Islands and the Isle of Man) is currently using less than 30 million numbers, which should allow plenty of room for growth. So why is there a problem ? Because the numbering ranges are tied to fixed locations by a formula that has no place in modern telecommunications, and which was originally introduced solely to enable fairly primitive mechanical equipment to route and charge calls correctly. As a result there is a serious imbalance in the distribution of numbers: one code, such as 0393, has only 25 numbers in use - while another, such as 0532, has over 300,000. The proposed extra digit will NOT solve the problem. Agreed it will create a lot more codes: but even now there are 56 codes that have no numbers on them, and that figure (surprisingly enough) is increasing, not decreasing ! But the extra digit won't provide any more numbers within each of those geographic areas served by individual codes, and that is where the brunt of the demand will be. Currently, growth is caused both by the need for more lines (particularly for fax) and by new operators taking blocks of numbers *within* the individual areas. Future demand will be driven by existing services such as DDI (Direct Dialling In to PABXs) which is a heavy consumer of numbers, and by new services such as Teenline, and Distinctive Ringing. The latent demand for DDI has been suppressed in the UK by both the lack of availability of connections, and by high tariffs imposed by BT. The arrival of DASS2 (the ISDN signalling system for digital PABXs) makes availability considerably easier, and Mercury and BT are now offering DDI at a much lower tariff. As demand grows, the larger cities will overflow their allocations of numbers and further complete changes will become necessary. It has recently been announced that five of those cities (Nottingham, Leeds, Sheffield, Leicester and Bristol) are to change to seven digit schemes in 1995: and looking at the list of codes vs numbering density in each (now, I believe, in the uk.telecom archives) it is clear that further places, including Brighton, Belfast and Bournemouth, are also likely to run out of numbers in the next few years. London's 071 was not expected to last beyond 2005 at the previous growth rates; however allowing for the greater demand caused by DDI and new services, the 071 number range is likely to be exhausted by the end of this decade. At that stage the two options will be either to split the 071 area into two codes, or to convert all of London to an eight digit scheme. This is not a new phenomenon ... even before London split into 071 and 081, two other capital cities (Paris and Copenhagen) had each tried an identical scheme. Those schemes failed, mainly because of confusion between "inner" and "outer" zone numbers, and each was superceded by an eight digit scheme which is reported to have been very successful. So we don't need an extra digit. And the extra digit (if we get it) won't solve any problems. We do need a complete overhaul of the numbering system, whether we have the extra digit or not. As that overhaul will have to come, it would be far better if we waited - and planned a single change that would solve all the problems, rather than have a hotchpotch of further changes. But - while the extra digit won't achieve anything for the customers, it will have an interesting effect on BT's sales figures. As soon as the extra digit is imposed, all Mercury Smart Boxes, SmartSockets, and compatible PABX and key systems will stop working unless they have been modified (at the user's expense) because they will be unable to recognise the longer codes. With the reduced differentials between Mercury's tariffs and BT's "options", some users may find it uneconomical to pay the charge for the modifications. Similarly, payphones supplied before 1992 by BT's competitors will be unable to charge correctly for calls. Some will have to be modified, at a cost, while others, that cannot be modified, will have to be scrapped. Some of those payphones are still on sale to unsuspecting members of the public without any warnings being given as to what is in store. ---- Question 04: Who owns this numbering space ? Answer: The numbering space is owned by the nation, and (technically) Oftel is its custodian. But in practise Oftel delegates the majority of decisions to BT, and takes advice from BT (and sometimes other operators) on major issues. If Oftel owned the numbering space and managed it effectively, Mercury would have been allocated 0800 and 0345 numbers to issue to their customers, rather than having to use new codes (0500 and 0645) which are still not recognised by some BT (and private) payphones. ---- Question 05: Is there a way I can pulse-dial a digital exchange number and then tone dial from there? Answer: Well, if you are not in an area served by Mercury, I would think the only way to do this would be with a BT ChargeCard - you pulse dial the "144", and can tone dial from then on. The main snag, (apart from the extra delay caused by entering your ID and PIN), is that you then have to pay for your call at call-box rates (10p/unit instead of about 6p). ---- Question 06: I want to get a BT Chargecard, the problem seemed to be that you need to be a current customer (have a phone) to be able to get one. Is this so? If it is why is it so? Answer: Sorry, but charges incurred on your Chargecard are put on to your phone bill. No phone -> no bill -> no chargecard. This should be catered for, in my opinion, but isn't. ---- Question 07: Can you use your subscription to Mercury in the same way as a Chargecard? I think I read that you are supposed to use it from only one phone. Answer: [There seems a little confusion over this, I'll leave both these answers in until I get some more information in...] It is I believe, strictly illegal to use your Mercury Code from other than your designated phone number. However, it may well be possible to to use it from any line on the same exchange as you. If I were you, I would wait until Mercury bring out their forthcoming Chargecard service, as I think they are unlikely to restrict this to existing BT subscribers only. Some time ago I asked Mercury whether they had/would have a chargecard scheme: they said no, but your mercury code can be used from any phone in your area code. So this would suggest its not illegal. ---- Question 08: I've heard someone mention about Mercury's 0500 service, what is it ? Answer: This is Mercury's 'freecall' service introduced at the end of 1992 and is their equivalent of BT's 0800 service. Similarly Mercury 0645 service, called 'localcall' is the equivalent of BT's 0345 service. ---- Question 09: Why can't I direct dial with my BT chargecard on Cellnet ? Answer: Apparently BT have not yet put the infrastructure in for direct-dial from any Cellnet phone, though operator calls are possible. Funny thing is, you can't make even operator calls from Vodaphone phones, even though you can supposedly make them from any country in the world with a BT Chargecard. ---- Question 10: Why is there no 0345 access to PSS Dialplus ? Answer: Two answers to this one : Although I work for BT the following can in no way be construed as an official BT response. Disclaimer out of the way, here goes: There are probably two main reasons why this is not done. 1) 0345 services (and 0800, 0898, 0891) were designed to give country-wide access at the appropriate charge rate to a specific number in a specific area of the country. There is probably also a method of directing calls originating in a specific area to a regional number - eg - 0345 123456 dialled in Brighton would route to a number somewhere in South East England, and the same number dialled in Scotland would route to a number in, say, Glasgow. In both cases the renter of the 0345 number pays for the trunk call part of the charge. The PSS service has PADs all over the UK, ie dozens of them, so that PSS traffic is not tying up trunk circuits. That would negate the whole point of the service!. The complexity of determining the 0345 routing to all these local PADs is probably not worth it. 2) The services are currently carried on an overlay network with its own exchanges. By their nature, most of these services are short holding time calls (despite the incidence of children spending long hours on chat-lines & pop music feeds), and the network is dimensioned for this. It is certainly not designed to carry relatively long holding time traffic to PADs! Perhaps, in the future Intelligent Network Databases will allow this sort of universal number access to lots of local nodes using the existing local network, but that's not imminent as far as I know. [However, another explanation has been proffered - Ed.] This question was asked, some years ago, at a `Character Terminal Implementors Group' meeting (a UK group which inputs to CCITT on the X.3, X.28 and X.29 recommendations, now defunct). The representatives from BT Network Services said that since BT was split up into different commercial divisions, BT Network Services would have to pay the full going rate for an 0345 (or 0800) number. That charge would obviously have to get passed on to the PAD user, and on average it would be higher than that of the phone calls made by the PAD user since the majority of them could make a local call. That's not a full answer, as there are bound to be savings in reducing the number of locations where PAD lines are located (be they real, or out-of-area lines to a PAD somewhere else), but it seemed as though BT Network Services were well aware of the possibility, and would take decisions on cost grounds. A factor which is obviously difficult to quantify is the value of having a single number which PAD users can call. One slight technical hitch is that an NUI is not necessarily known at all PAD centres. ---- Question 11: Say I want to access my University computer from home, using an ISDN connection, in order to get fast terminal access and file transfer. What would the full installation & rental cost be, both for me and the University Computing Service? What would I need to connect a PC to a Sun over this ? Answer: For ISDN2 (Basic Rate Access), the connection charge is #400.00 and the quarterly rental is #84.00. Call charges are the same as the normal PSTN. You will need a terminal adaptor at the Unix end, and a PC card in the PC. Terminal adaptors are around #1000. Software is dependent upon what you wish to run over the link. An async terminal connection will probably not utilise the full bandwidth available. It is possible to run IP over the link. ---- Question 12: Is it possible to set up a three way call, then have one of the other guys introduce another caller.. ad infinitum? Answer: Yes and no. With Network Services three way calling, it is possible to introduce a third caller. There is supposed to be a facility (it was mentioned in one of the BT network guides) to introduce 8 callers. However, if you have a PABX, you may be able to do this anyway using the conference call facility. ---- Question 13: What *are* these Network Services that people keep mentioning? Are they a BT version of teletext or something? Do you have to pay for them? Answer: Culled from information provided by P.K.Chawdhry@newcastle.ac.uk (Pravir K Chawdhry), clive@x.co.uk (Clive Feather) and pkh@cs.nott.ac.uk (Kevin Hopkins). Network Services are available on BT's digital exchanges (System X and System Y) and are usually available on the payment of a quarterly rental, though some are available solely on the payment of a per usage charge. [PLEASE NOTE: This is just a summary, for a full list and charges please] [ see the seperate posting "BT Network Services information"] Set up features: 5 == Retry When Not Busy (when busy tone heard) [System Y] *21*number# Call Diversion (all calls) *261# Call Barring (incoming) *34bar# Call Barring (outgoing) *40*number# Call Charge Advice [System X] *40*number Call Charge Advice [System Y] *411# Call Charge Advice on all calls *43# Call Waiting *51*code*number# Code Calling *55*time# Reminder Call *56*time*programme# Reminder Programme [System X] *61*number# Call Diversion (no reply) *61*number*wait# == Call Diversion (no reply) [Extra System Y facility] *67*number# Call Diversion (on busy) Calling code calls: **0 Repeat Last Call (excluding Calling Code calls) **code Code Calling call Status checks on settings: *#001# Check which services are active [System X] *#21# Call Diversion (all calls) *#261# Call Barring (incoming) *#34# Call Barring (outgoing) *#411# Call Charge Advice on all calls *#43# Call Waiting *#51*code# Code Calling *#55# Reminder Call *#56# Regular Programme [System X] *#61# Call Diversion (no reply) *#67# Call Diversion (on busy) Cancel features: #21# Call Diversion (all calls) #261# Call Barring (incoming) [System X] #261*keyword# Call Barring (incoming) [System Y] #34bar*keyword# Call Barring (outgoing) #37# == Retry When Not Busy [System Y] #411# Call Charge Advice on all calls #43# Call Waiting #51*code# Code Calling #55# Reminder Call #56*time*programme# Reminder Programme [System X] #56# Reminder Programme [System X] #61# Call Diversion (no reply) #67# Call Diversion (on busy) ---- Question 14: I use Network Services to bar incoming calls, but when the barring is in force, the dialtone is different, and hence my modem won't autodial. Is there a way round this? Answer: With most Hayes compatible modems you can use the ATX command to prevent the modem from looking for dialtone before it dials. This solves the problem of having to worry about it finding the dialtone. ---- Question 15: When I called 175 from home there was a message telling me my phone number, then when I hung up I was called back and offered a mysterious menu. Anyone know how to work it? Answer: 1. Dial 175 2. Exchange answers and says "You are connected to . Start test." 3. Hang up 4. Exchange calls back and says "line testing ok" (assuming it is ok, of course). Then it enters a loop, inviting you to "dial next test" and performing a test based on the single-digit code you give it. From memory, test 1 is the keypad test (dial 123456789*0#) and 3 is the coin pulse test. [This is the fullest list available so far - Ed.] System X Subscribers Apparatus Line Test (SALT) facility DIGIT 1 (Dial Test) - Expects "123456789*0#" to be dialled DIGIT 3 (CCB Test) - Sends 'open slots' + pay tone to line under test Expects coin insertion indication from line (Measures coin insertion signal characteristics and checks result) Sends coin pulse ACK signals to line DIGIT 4 (SPM Test) - If SPM is provided on the line 50Hz SPM 5 long SPM pulses sent to line followed by NU tone. 1 second timeout then 5 short SPM pulses. 16KHz 10 pulses of nominal characteristics sent to line without burst on NU tone DIGIT A (MF4 extra) - Expects "ABCD" to be dialled. ---- Question 16: Is Caller ID available in the UK ? Answer: It is available as a trial service in the Keith/Elgin areas of Scotland, and the full roll-out is expected in very early 1994. Mercury do not presently offer CLI on their directly connected lines, but it is understod that they will in future. The almost definitive CLI statement from a source in BT Networks... The Calling Person's Number is carried in the MTS C7 header along with a flag to indicate if the CLI information is free for release. Currently this flag is only set for calls originating from ISDN where the customer has opted for its release. The CLI information, however, will be there for all calls that originated from customers at System X, AXE10 or enhanced TXE4 exchanges - although there are currently some problems with the AXE10s. CLI is always sent to 999 and other operators regardless of the release flag. ISDN customers who have opted to receive CLI will receive it only from those who have the release flag set - currently only other ISDN customers. ISDN users in other countries will again receive it only if the release flag is set and the call has been routed over one of the ISDN-friendly digital paths - international ISDN costs more than normal international calls so customers can opt to choose a standard path for their call which is not guaranteed to work on non-voice calls. For most non-ISDN international calls, the CLI information is stripped from the header regardless of the flag and not passed on to the other telco. Releasing the CLI to ordinary lines: This is to be supported via frequency shift keying techniques, sending the CLI to line prior to ringing. You will need a 'decoder' on the other end of the line to display the digits. System X exchanges do not currently support the release of CLI via FSK although they will do in the very near future. The actual sequence (greatly simplified!) is as follows: A - Calling subscriber B - Called subscriber SUB A ORIG EXCH DEST EXCH SUB B A dials PSTN number of B -------------------------------------------> Ringing Tone Line reversal <------------------------------------------- ------------> FSK (calling number) ------------> Ringing Current ------------> I.e. the "awaiting answer" indication (ringing tone) is sent prior to actual ringing current being applied to the called subscriber. This is because the calling number delivery may actually take up to 2 seconds before ringing is applied. So you will continue to get the ringing tone very quickly, but the phone on the other end may lag behind by a second or two (in terms of the ringing, of course). ---- Question 17: Can I get a fully itemised bill from BT ? Answer: rom: roy@harlqn.co.uk (Roy Badami) Yes, with the proviso that you are on a System X or Y exchange. Continuing with the general paranoia of the previous answer... : It's been claimed on this group before that modern exchanges record time, duration and destination of _all_ calls, regardless of duration. (And keep them rapidly accessible, if not actually on-line, for 6 months.) I've always assumed that the notion of `meter reading' is just notional, to avoid having to record all the calls on the bills they send out. I've heard it said that if you dispute the number of metered units you've used, BT will send you a fully itemized bill, which includes all calls -- not just those of 10 units and over. ---- Question 18: How can I phone American 1-800 (toll free) numbers from the UK ? Answer: [Distilled from an article forwarded onto uk.telecom from comp.dcom.telecom by gtoal@robobar.co.uk (Graham Toal) by ccs@aber.ac.uk (Christopher Samuel) ] I'm afraid the answer is no. The service which has been mentioned a few times turned out to be illegal and was defrauding the PTT for a large sum of money ("several thousand dollars" cropped up). Persons outside the of the United States are generally not able to call US 800 numbers for technical and billing reasons. The number was probably an unrestricted DISA (Direct Inward System Access) port, and resulted in the use of phone lines without the companies knowledge or permission. ---- Question 19: How do I dial a number with a mnemonic in it ? Answer: Here's a letter to number mapping; this is particularly useful because many 1-800 numbers have mnemonics in them. I got these from a request in uk.telecom round about the end of September last year. Num UK USA 1 2 ABC ABC 3 DEF DEF 4 GHI GHI 5 JKL JKL 6 MN MNO 7 PRS PRS 8 TUV TUV 9 WXY WXY 0 OQ Operator There is no 'Z' in either system, and there's no 'Q' in the States. ---- Question 20: Where can I get an old style BT phone box from ? Answer: A couple of people suggested looking in small ad's in Sunday newspapers, Private Eye or Exchange and Mart. One or two people suggested contacting BT directly, but nobody claimed to have tries this or gave any suggestions as to which bit of BT to try. Mark Whidby (M.Whidby@mcc.ac.uk) remembers seeing a company with a yard full of 'phone boxes near Staleybridge. I looked for the adverts and found a couple in Exchange and Mart. One company in Essex (0277 899 495, Michael Smith) does them in off-street condition for UKL350+delivery+VAT or reconditioned at around UKL975+delivery+VAT. Another company (061 767 9259) does them for UKL375+delivery (off-street) or UKL1250+delivery reconditioned. They said that there was no VAT (presumably they're a smaller company who aren't VAT registered?). They told me that customers usually found it cheaper to buy them reconditioned than to resort to DIY. Reconditioning includes stripping, filling and repainting the cast iron frame, replacing glass (including the `Telephone' signs), guilding the crowns and refurbishing the doors (which were apparently made of teak; I'll check this out with a magnet sometime). Customers who did their own refurbishment usually did it for pleasure or sentimental value rather than to save money. Delivery would cost UKL125 (from their Birmingham depot to me in Essex), or I could collect if I happened to have a lorry and a fork-lift. Suggestions for uses were showers, drinks cabinets, fish tanks, to grow plants in, to house a telephone, ... ---- Question 21: What is the Mercury beep, and can I get rid of it ? Answer: The answer beep can annoy customers, if it occurs once the person has started speaking. In some areas, it is immediate on answer and therefore no problem. It *can* be removed for specific accounts on request although Mercury are reluctant to do this unless essential. The beep triggers call logging/charging equipment, such as hotel switchboards and payphones, and although it is currently applied to all indirect calls via Mercury (except where the customer has requested its removal), Mercury are planning to withdraw it from all those customers that do not specifically require it. ---- Question 22: What types of exchange are there, and which can be digital ? Answer: The types are: a) Strowger - rotary switches, etc (UAXs, SAX, TXS) b) Electromechanical crossbar (TXKs) c) Electronic-control reed-relay switches (TXE2) d) SPC non-digital (TXE4*) e) Digital (Systems X and Y: may be further categorised as to whether they're ISDN-capable, I suppose) Now, type (a) accepts your dialling at the point in the switching matrix that your call has so far reached. Every switch has its own dial pulse decoding and routing intelligence. Short of generating the dial pulses at the MDF (where the lines come into the exchange), there's no way to convert them to DTMF. And what would be the point? - pulsing dial pads are _so_ cheap that pretty much everyone's telephone can do the job. All but type (a) accept the digits you dial into a register, and make the routing decisions centrally based on the contents of the register. In principle, any such exchange can easily be converted to accept DTMF: it simply requires a different input box for the register. (Historical note: the first electronic research exchange to hit public service in the mid-60s, the TXE1 at Leighton Buzzard [RIP] was DTMF capable. As a person involved with fiddling 'phones at the time, I arranged to go round it with some like-minded friends: we were shown a DTMF 'phone in the exchange manager's office, and were told that there was precisely one `public' user of the service.) Pretty much any SPC exchange (types (d) and (e)) can in principle offer network services. We know that type (d) can in some cases, since we've had a post to that effect from someone at STC (was it - sorry, I've forgotten your name). We know that type (e) can do it, since they all do... So there we are: since the advertised date for upgrade is 1998 (that'll teach you to live in Scotland!) I would guess that the original exchange is a late-model TXE2, and that the provision of DTMF was a sop to the punters... ---- Question 23: What is the difference between a System X and System Y exchange ? Answer: Quoting Raymond Okonski (known in the business as "Buzby"): Post Office Telephones designed a modular, digital telephone system with Plessey. Other manufacturers complained that it was unfair a monopoly was abusing its power by precluding other suppliers. A complaint was made to the Government and they agreed - at least TWO suppliers to the PO/BT would be required. Ericsson's made the AXE10 which offered practically the same flexibility in a smaller box - mainly because System X was designed by a committee, it was already old before the first release model was available. The AXE10 was renamed by BT to 'System Y' just to keep things 'simple'. If anything the AXE10 is more fully featured than the 'X' but BT only took the basic software package one each, so both offer practically the same. Incidentally, Cellnet tried to use System X as their mobile switched but dumped it as it was very old tech. Vodafone tried Ericsson, and that is why Vodafone runs totally on AXE10's! ---- Question 24: When I use call waiting, and I hear the second caller incoming beep, and press R to get the dialling tone so that I can press 2 to get to the new caller, nothing happens i.e. no dialling tone. Answer: You may have switched your phones to tone dialling but there should be a separate switch to change the type of recall from Earth Loop to Timed Break (which is essential to use Call Waiting fully). Sometimes there is only one switch, three position (LD/MFE/MFT) in which case you want MFT. Some MF phones do NOT have the Timed Break (MFT) option - in which case you would need a new phone to make full use of the service. ---- Question 25: What do PSDN and ISDN mean ? Answer: PSDN Public Switched Data Network ISDN Integrated Services Digital Network In this country, PSDN exclusively refers to BT's PSS (and any Mercury competitor?), which is(are) an X.25-based network(s). From BT you can buy (at exorbitant cost) leased-line connections to PSS at various speeds - contact their sales people. Simply speaking, ISDN provides the customer with the 64kbit/s that PCM digital representation of speech occupies, but doesn't insist that it be used for speech. The simplest connection you can buy offers `2B+D', which is 2x64kbit/s with a 16kbit/s signalling channel. In principle, you can send rather wimpy video with 128kbit/s, but it would have to be highly compressed, at low resolution and with a low frame rate (like in a picture-phone). Some BT exchanges offer ISDN (to find out whether _your_ exchange can offer it, you need to talk to their sales droids again), and it works out rather more expensive by way of line rental than does an ordinary line, but call rates (apart from special offers) are the same. At least some other carriers also offer ISDN - try asking those that are to be found in your area (for example, I believe Cambridge Cable do round here). Note that an ISDN connection to Mercury via 131 (even if Mercury have ISDN capability) is probably a no-hoper. ---- Question 26: How do I stop my answering machine recording the "Please replace the handset & Try Again" message when someone hangs up without leaving a message ? Answer: Ring BT on 150 or 152 if this happens. They have a VERY simple way of turning off that recording so that it doesn't happen again ! ---- Question 27: Why are my Telecom Gold charges higher than I was expecting ? Answer: In the New Scientist 6 Feb 1993 p84 there is mention of: ".... Telecom Gold, automatically takes old messages, and without warning.... stores them away and charges over 20p a month for every 200 words of text..... ..... To check for hidden mail, when you get the main prompt, key in: MAIL QSC FI *READ...... this reveals what there is there. Then use the standard delete commands so that BT can no longer charge you for keeping it there". ---- Question 28: Who or what are AT&T Direct ? Answer: AT&T Direct is a way to contact the AT&T operator in the USA without having to ring any operator in the UK (or whichever country you happen to be in). You can contact AT&T in the UK, on 071 355 6000 or via AT&T direct itself on 0800 890011. You would need an account with AT&T to use it to call the USA: it *may* be cheaper than dialling via BT but don't bank on this. Other phone companies in the US, such as Sprint on 0800 890222, offer similar services. [Someone else proffered this information - Ed.] When I last compared rates between AT&T, SPRINT, MCI, BT & Mercury (I have accounts with all five...don't ask why). Mercury seemed to be about the cheapest, but had the poorest quality connections. The real killer with all US carriers is the 1st minute charges. I think it costs over $3 for the first minute. It's not too bad averaged out over a long call, but if you get an answering machine on the other end you are stuffed. With Mercury if I get an answering machine it costs 10-20p for the call. I know MCI has a scheme that will allow UK residents to have MCI cards, I don't know about SPRINT and AT&T. Here are the UK numbers for: MCI: 0800 89 0222 SPRINT: 0800 89 0877 ---- Question 29: What is known about PIN-less Mercury ? Answer: The code will be 132. Users will have to register their calling lines with Mercury (the system uses the Caller-ID of the calling line) and the service should be on trial very shortly in Reading. Later it should be rolled out to the rest of the UK. ---- Question 30: How do I get a guarenteed non-satellite circuit to the USA ? Answer: To get a guaranteed non-satellite circuit to the USA, useful for certain data transmission requirements which involve a lot of handshaking, dial 0101 83 + area code + number. The code 84 allows you to obtain a satellite link, if you really want one for any reason. And before someone asks -- no, it doesn't allow you to dial 800 or 900 numbers. I believe it did once. ---- Question 31: How do I order BT's full price list ? Answer: >> The BT price list I ordered finally turned up... it wasn't what I >> expected - it's a thin leaflet with basically little more information >> than the residential price guide you get with your bill. Then it simply isn't the *price list*. It may be what BT try to fob you off with when you ask for a copy of the price list. Now ring them back and insist on the REAL THING ! (BT reference is TRF/BTP/A100 et seq.) ---- Question 32: Why does my pre-socket phone 'tinkle' in the night ? Answer: There have been postings regarding telephones `tinkling'. It has also been posted in reply that this is attributable to line testing. Apparently lines are now tested every hour or so. They are tested by detecting the capacitor in the phone socket. Pre-socket phones are still tested OK, but the capacitor is actually in the phone. Hence it tinkles when tested. My friendly engineer told me that when BT get complaints about this, they just tell the customer 'We are just testing your phone line automatically to ensure continued good service, etc..' then follow with 'Your equipment is out of date, how about us coming round so that we can offer you an improved service, it will cost you... etc.' ---- Question 33: How does the BT Chargecard system work ? Answer: This may interest those who are trying to guess how Chargecard works. It is wholly cribbed from "The Cashless Services System" by N.G. Pope in "British Telecommunications Engineering" Vol 9, July 1990. Customer dials 144. The call is routed to the nearest digital exchange, which adds 3 digits identifying the charging area of the caller. It routes it to the trunk exchange (Digital Main Switching Unit or DMSU) which routes it to one of 30 Cashless Services Processing Units (CSPUs) where it terminates. As far as conventional charging is concerned it is effectively a free call. There is now a through transmision path from telephone to CSPU. Payphones are (internally) programmed to switch to MF after receiving 144. The CSPU sends a burst (1 second) of 1600Hz tone. If the originating phone is a payphone it will send its identity (9 MF digits) to the CSPU - (for stats on public payphone usage perhaps, it doesn't say?). Ordinary phones will not respond to the tone. CSPU returns prompt to dial a/c number and PIN. 12 MF digits are received and stored. An X25 link connects CSPU to the Cashless Services Database (CSDB), and the incoming PIN is encrypted and compared with the encrypted PIN on the CSDB stored against the customer's actual record on the database. Validation takes about 100ms. CSPU returns a message to the caller to enter the required telephone number. The CSPU stores enough digits to route the call which is routed back to the DMSU and on through the PSTN (Public Switched Telephone Network). The CSPU remains in circuit throughout the call. At the end of the call the CSPU sends an itemised billing record (from where to where, start time, duration etc) to the CSDB which then performs the billing calculation and passes it to the telephone input billing system (TIBS). The article goes on to explain the hardware etc. Earlier on it says "There are various ways in which an automatic Chargecard service [could] be introduced into the network. Ideally the software would be built into the software of an intelligent local exchange with account number/PIN validation being carried out in an intelligent network database (INDB). This is considered to be the ultimate solution to the problem of providing the service. However in 1986 [when the service was envisaged] this solution was not a practical proposition and so an alternative had to be found. [The present system]" (All information is from the public domain) ---- Question : Where can I get further information from ? Answer: ONLINE: There are two other telecoms related newsgroups which I am aware off. They are comp.dcom.telecom and alt.dcom.telecom, but be warned, they tend to be dominated by US specific items, and the comp hierarchy one is moderated as a gatewayed digest, so articles MUST be submitted to the moderator for approval. (Submissions: telecom@eecs.nwu.edu, requests to telecom-request at same address) FTP: There is now a uk.telecom archive at Imperial College in: src.doc.ic.ac.uk:/usenet/uk.telecom It contains both an 'rkive of the group in volume92/, volume93/, etc with an index by subject in the file Index, and a small archive of useful files in the 'archive' directory, including the latest versions of the FAQ and the network services posting. For anonymous FTP, the Usenet newsgroup comp.dcom.telecom has an archive site at lcs.mit.edu [18.26.0.36], with a quite comprehensive suite of files, including some UK specific stuff. DIRECT CONTACT: You could try BT, or Mercury direct, if you really want to. [My thanks to Kevin Hopkins for these numbers] For BT enquiries the phone numbers are: BT Line Any Line Residential General Enquiries 150 0800 800150 Residential Fault Reports 151 0800 800151 Business General Enquiries 152 0800 800152 Business Fault Reports 154 0800 800154 There is also the BT news line: --- 0800 500005 For Mercury enquiries the phone numbers are: General Enquiries 0800 424194 Fault Reports 0800 424193 Billing Enquiries 0800 424196 For some of the other carriers: AT&T Direct: 071 355 6000 or: 0800 890222 MCI: 0800 89 0222 SPRINT: 0800 89 0877 Another source of information are Mandarin Technology, who have told me that they do try to help anyone needing more telecom-based information, especially in the regulatory fields, and are equally happy to respond to enquiries received by voice, fax or email. Details (pinched from Richard Cox's .signature): Mandarin Technology, Cardiff Business Park, Llanishen, CARDIFF, Wales CF4 5WF Voice: +44 222 747111 Fax: +44 222 711111 VoiceMail: +44 399 870101 E-mail: mandarin@cix.compulink.co.uk Wish List: 1) UK versions of comp.dcom.telecom archive files. Thanks section This FAQ would not have been possible without contributions, help and support from the following people: mandarin@cix.compulink.co.uk (Richard Cox), keith@unipalm.co.uk (Keith Mitchell), tjo@its.bt.co.uk (Tim Oldham), gta@uk.ac.st-andrews (Graham Allan), jcs@zoo.bt.co.uk (John C Sager), cudac@warwick.ac.uk (Tim Clark), cc_s425@kingston.ac.uk (Syngen Brown), brian@rtf.bt.co.uk (Brian N Butterworth), malcolmr@sun.pcl.ac.uk (Malcolm Ray), mandarin@cix.compulink.co.uk (Richard Cox), steveh@orbital.demon.co.uk (Stephen Hebditch), chris@visionware.co.uk (Chris Davies), ags@uk.co.gec-mrc (Gavin Spittlehouse), rf@cl.cam.ac.uk (Robin Fairbairns), ranald.mcintyre@almac.co.uk (Ranald Mcintyre), mcneill@devon.co.uk (Keith McNeill), mark@mozart.demon.co.uk (Mark Whalley), fisher@minster.york.ac.uk (Tony Fisher), shakib.otaqui@almac.co.uk (Shakib Otaqui), gdk@ipg.ph.kcl.ac.uk (Gary Kendall) -- Christopher Samuel, Computer Unit, U.W Aberystwyth, Aberystwyth, WALES E-mail: ccs@aber.ac.uk PGP 2.3 public key available on request "Some say the gods are a myth, - The Waterboys but guess who I've been dancing with." "The Return of Pan"