TELECOM ACCESS STANDARDS NEWSLETTER NO. 88 FEBRUARY/MARCH 1996 CONTENTS 1. CORDLESS AND CONVENTIONAL TELEPHONES - SAMPLES FOR TESTING 2. TRUNK LOSS ADJUSTMENT FOR CPE 3. RINGING DECODER COMPATIBILITY PROBLEMS 4. CONNECTING "SERIES" CPE 5. ISDN CPE POWER REQUIREMENTS 6. ANALOGUE INTERFACE OR POTS LINE? 7. ISDN TERMINAL ADAPTER REQUIREMENTS 8. FRAME RELAY EQUIPMENT TELEPERMITS 9. TWO-WIRE TRIAL 10. BELL AND SOUNDER WIRING 11. ELECTRICAL SAFETY TESTING 12. "FAXABILITY" FAX MACHINES AND OTHER RINGING DECODER-EQUIPPED CPE 13. ORDERS FOR ACCESS STANDARDS DOCUMENTS RETURN TO MAIN INDEX 1. CORDLESS AND CONVENTIONAL TELEPHONES - SAMPLES FOR TESTING Telephone suppliers will be pleased to hear that we are reducing the number of samples required for testing conventional telephones from 20 down to three, as from 1 April 1996. On the other hand, we will also require three samples of each cordless telephone model, rather than the present one. The reasons for these changes are as follows:- Loudness rating testing Test results received over the past year or so have shown that close tolerances on loudness ratings are now being achieved by almost all manufacturers. Most telephones are chip-based rather than built up from a large number of discrete components, such that the send and receive loudness ratings are commonly determined by a couple of resistors. The transducers also seem to be of closer tolerance these days and we feel that there is now little additional risk if we accept products on the basis of a reduced test sample. We reserve the right, however, to call for a follow-up test of 20 samples if there is severe disparity between the test results on the original three samples or service problems are experienced once the product is in service. Using three CT samples will also allow a better level of assurance that cordless telephone transmission performance is within reasonable tolerances. Cordless telephone security In Newsletter No. 86 I mentioned a problem with cordless telephone security. We have had cases where single portables have been found to generate two simultaneous calls into the network by picking up a nearby base station in addition to their own. The exact cause is not yet proven, but it appeared that some models of CT could lose their security code if the batteries were removed or allowed to stay flat for a long time. As far as we can gather, reconnecting the portable to the base unit generates a new security code, but the algorithm used to generate that code may be common to all units of that model. This dual call problem generates two call bills and, of course, complaints from the customer who did not make the call. Even more seriously, the results of the second call can have financial or other liability implications for the customer affected. If so, this could also involve liability for the supplier. This situation will not be acceptable under the terms of PTC 200. We will require suppliers to either give a formal assurance that such duplicate security code regeneration cannot occur. Alternatively, where the supplier is not sure of the design parameters, we will have the test laboratory carry some simple tests as part of the compliance procedure. These moves will not absolve the supplier from potential liability if some other mechanism exists, but it should at least minimise the risk of the problem being worsened. These changes will be incorporated into PTC 200 when it is published. In the meantime, reasonable notice of the changes are being given so that suppliers can choose whether to provide the 20 samples for testing before 1 April or provide three samples and have testing done after that date. This notice will also give suppliers the chance to ensure that three cordless samples are available for testing and make enquiries regarding the nature of the security code allocation/regeneration process if one exists. 2. TRUNK LOSS ADJUSTMENT FOR CPE An increasing number of "complaints" have been received lately by our operations staff, where customers or CPE installers are demanding that Telecom makes switch adjustments to compensate for shortcomings in the customer's equipment. It appears that many customers think Telecom has some obligation to investigate and remedy another party's setting up problems if the products concerned are Telepermitted. This is, of course, not the case. In some cases, there is nothing actually wrong with the CPE concerned. It simply "sounds different" to what it replaced. No doubt the customers concerned would become accustomed to the new product in time, but first impressions result in requests for some amplification. I have dealt in the past with the problems of echo on long distance calls (Newsletters No. 56 and 57 included major articles). In the current cases, long distance calls are not the immediate problem. Typically, either the PABX or its terminal equipment has been incorrectly set up such that its transmission performance is seriously impaired on all calls, or the new system is significantly different to the older one and both were within the accepted limits. In general, Telecom does not engineer its lines to compensate for the characteristics of customer premises equipment. The main reason for this is that the products connected to a line are required to be Telepermitted. As such, they are expected to fit within the transmission level requirements of our relevant PTC Specification. If one item of CPE is "wrong" and we were to compensate for it, then problems would arise from over-compensation as soon as the customer used CPE that does comply with PTC Specifications on that same line. Assuming that the CPE concerned does meet our transmission requirements, the overall transmission performance is dependent only on the characteristics of the analogue line used by the customer concerned. We compensate for line loss in extreme circumstances, but any gain must be very sparingly applied as it has a "doubling effect" on the echo performance for calls to or from that line. Echo problems usually affect only the distant party on a call, not the customer who has requested the adjustment. Where a customer experiences difficulty with newly installed CPE, it is up to the supplier of that CPE to properly set up any variable transmission parameters and to confirm that the equipment is not faulty. 3. RINGING DECODER COMPATIBILITY PROBLEMS Recently, a case arose whereby some non-Telepermitted ringing decoders were released to the market. These particular decoders were line polarity dependent. As such, they conflicted with a fundamental PTC requirement, which was explained in Newsletter No. 85. To get over this problem, the supplier had fitted a switch to be operated by the customer according to the polarity of the line to which the particular decoder was connected. A high proportion of our lines are no longer simple copper pairs. Instead, they are derived from various types of subscriber PCM systems, radio and carrier links, etc. One widely used variety of subscriber PCM changes the line polarity during its call set-up and release procedures. We received a customer complaint and our serviceman found that the customer had recently connected a decoder to one of these lines. The problem was that the two systems were simply incompatible. The polarity changes caused the decoder to drop the call and the customer could not be expected to manipulate the switch during call set-up. Suppliers are reminded that Telecom has every right to charge customers for service calls if they have connected non-Telepermitted equipment in breach of their service contracts. In turn, those customers have the right, not only to return the goods as "unsuitable for their purpose", but also to demand that the retailer compensates them for Telecom's charge under S.18 of the Consumer Guarantees Act, 1993. The Ministry of Commerce publishes a number of information booklets on these legal issues. Suppliers and retailers who are not yet familiar with the provisions of the Consumer Guarantees Act should find these to be very helpful. 4. CONNECTING "SERIES" CPE A recent service problem should be of interest to suppliers of "series-connected devices", i.e., those that physically connect from one CPE to another, rather than direct to the jackpoint. These include Ringing Decoders and, later, Caller Display units, some of which use the same RJ plug as the phone end of the line cord. The intended means of connection was to remove the telephone plug from the jackpoint, plug in the series unit and then plug the telephone into the series unit. All very simple and straightforward - in theory. What happened was that some customers unplugged the telephone line cord at the telephone and connected the line cord into the series device. The series device was then plugged into the telephone. Unfortunately, the customers concerned were able to make the physical connection without difficulty. There are crossovers in the pin wiring when a cord has a BT plug at one end and an RJ at the other. The connections at the RJ plug end and the crossovers are not standardised. As a result, some customers found the telephone did not work with the series device provided. The moral of this story is that the connection arrangements should be made absolutely clear to the customer - preferably via pictures of the connections. If this is not done, everyone concerned may be put to a lot of unnecessary trouble. 5. ISDN CPE POWER REQUIREMENTS As mentioned in Newsletter No. 85, Telecom uses several different models of Network Terminating Equipment (NTE) for its ISDN service and further versions are bound to be used in the future as the technology advances. NTE's vary in their power supply characteristics, some providing only "restricted" power, while others provide "normal" power capability. There are also variations as to whether Power Sources 1, 2 or 3 are provided. This arises because Telecom tends to purchase standard overseas hardware, rather than demand special versions for our relatively small market. Most ISDN CPE to date has been mains-powered, but line-powering is likely to become more popular as power loads drop. Even some mains-powered types depend on the presence of the NTE power supply as a means of detecting that the line is in service. The type of NTE used can thus be critical. We are working on the preparation of PTC 231 to improve the present definition of ISDN terminal equipment requirements and one of the changes will be that the Telepermit applicant will be asked to state the NTE power requirements. Also, where specific NTE conditions are necessary, the supplier is to advise customers to inform Telecom of these requirements when ordering ISDN service. This will apply to new connections of the CPE concerned and where existing CPE is to be relocated onto a different line. Telecom will then either be able to provide the appropriate NTE or advise the customer to arrange special powering with the supplier concerned. By communicating requirements fully, we should be able to avoid unnecessary delays for the customer and suppliers should be able to avoid unnecessary complaints that the CPE does not work correctly. 6. ANALOGUE INTERFACE OR POTS LINE? With the growing use of ISDN, there is also increasing use of terminal adapters to produce an analogue interface. Customers do not usually recognise that there is a subtle difference between such interfaces and what might be termed a "standard" Telecom PSTN line. This is commonly referred to as a "POTS" line, although the increasing range of supplementary services is tending to weaken the traditional definition of "POTS". For example, with Distinctive Alert ringing cadences and Caller Display functions appearing on the analogue telephone network, customers will be purchasing the necessary CPE to support these services. However, should they later take ISDN service and use a terminal adapter, these supplementary services will almost certainly be provided in a different way. The customer's PSTN CPE may not function when connected to the analogue port of the terminal adapter. Part of our PTC 231 work is endeavouring to recognise and take account of these constraints. In the meantime, it would be helpful if suppliers of terminal adapters would make such distinctions clear to their purchasers by explaining that the two interfaces are not necessarily exact equivalents . 7. ISDN TERMINAL ADAPTER REQUIREMENTS We are currently working on the preparation of a set of requirements for ISDN terminal adapters. The draft document concentrates on the analogue interface, as described above. Adapters specific to other interfaces are not covered, and they need to be dealt with by ensuring compliance with the specifications of the particular interface they provide. In line with recent practice, these requirements will be published in the form of a "Draft for Public Comment" in the next month or so. This approach is being used now that we are aiming for a set of "loose leaf" specifications, which can be considered in separate modules, as and when the need for publication arises. The final requirements are expected to be incorporated into PTC 231. 8. FRAME RELAY EQUIPMENT TELEPERMITS It has come to our notice that some Frame Relay link multiplex equipment is also being used for voice calls connected to or from the PSTN. The requirements for equipment having this capability are covered in Specification PTC 217, which also applies certain conditions on its use for PSTN calls. Some of these devices concerned have not been Telepermitted. Others have been Telepermitted on the basis that their primary function is the transmission of data, so voice quality has been ignored or overlooked. This arose where the voice facility was not stated on the initial application, or it was regarded as a secondary function used only for point to point communication between the two specific data terminals. We have not been concerned about the quality of the voice transmission on private links, but we are concerned if the voice link is connected via the PSTN for calls to or from another party. The conditions for voice connection given in PTC 217 must be applied in such cases. It must be stressed that when Telepermit applications are made, ALL facilities that affect the assessment must be stated. Certain companies are being contacted directly on this matter, but the purpose of this article is to ensure that all readers concerned with this market are aware of the PTC requirements. This class of equipment can directly affect the service provided to our customers. If it imposes inferior speech quality on their calls, they need to be warned of this as part of any offer to sell it to them. 9. TWO-WIRE TRIAL In Newsletter No. 81 I outlined our proposals to convert premises fixed wiring from 3-wire to 2-wire connection and described the proposed new 2-wire jackpoint. Since that time, Telecom has been studying the design issues and arranging for an initial batch of jackpoints to a new design. These will be used in a trial which will cover only a few hundred installations. This is expected to start within the next week or so. Our aim is to confirm the effectiveness of the new system and determine whether further design improvements are justified. We will then finalize the PTC requirements and publish a new specification so that supply of these jackpoints can be opened to competition. The timing for this final stage will not be known until the trial results are available, but we are hoping we can get the system into full-scale use by mid-year, if not a little earlier. For the information of jackpoint suppliers, the basic parameters are very much what was described in Newsletter No. 81. We had initially proposed a heavier protective nickel and gold plating on the socket springs, but tests revealed this was not as successful as we had hoped. The thicker plating was prone to cracking and this meant the additional protection was largely ineffective. As a result, we are currently basing the jackpoint design on the use of the "tropicalised" socket manufactured by Pre-Met in the UK. This particular socket is already widely used by local importers and by Telecom's own contractor. The capacitor will be a 1 µF polyester type, rated at 250 V d.c continuous, 400 V peak. Other than for its capacitance value, the component is the same as that currently used in "Master" jackpoints. The circuit board layout is essentially as I sketched out in the original article, with maximum practicable clearances between tracks. The original Krone IDC strips will be retained, but there is no surge suppressor or resistor and, of course, no separate master and secondary versions. One significant difference between the old and new designs is the use of a protective coating over the entire assembly. This involves a "dipping" process and the use of "Fluorad FC 722", a special protectant material manufactured by the 3M Company. Unlike the conventional conformal coatings, which cover only the board and component outer surfaces, Fluorad also coats the Krone IDC contacts and the socket contacts. Its "special" characteristic is that it "wipes off" the actual contact points as a plug or a wire is inserted and gives a good reliable contact. The remaining coating protects the backs of the springs and otherwise exposed metal from corrosion. Coatings of any type, conformal or Fluorad, are ineffective if they are used over contaminated surfaces. In principle, this is like painting over rust without first removing it or curing it. It is a very short term solution. A key part of the manufacturing process is that thorough cleaning of the whole assembly is needed before the coating is applied. This means that factory processing needs to be well controlled. Needless to say, the overall aim is to improve the reliability of our customers' services. Customer premises wiring faults are one of the most common causes of problems for our customers and jackpoint corrosion is, in turn, one of the most prevalent causes of these wiring problems. Going to 2-wiring and avoiding the line impedance imbalance of the third "ringing" wire is practicable now that we have little or no decadic dialling and relatively few over-sensitive bellsets. Our aim is a set of reasonably simple and low cost improvements which can be expected to have significant benefits in the long term. I hope to be able to announce the availability of the draft PTC specification, PTC 223, with the next Newsletter. In the meantime, the above progress report will be of assistance to line hardware suppliers. Hopefully, it will allow them to reduce their stocks of existing product and phase in 2-wire hardware to match Telecom's own installation programme. 10. BELL AND SOUNDER WIRING The conversion to 2-wire operation will enable a general tidy-up of customer wiring. One of the aims is the progressive replacement or retermination of all earlier mixed wiring systems which resulted from partial jackpointing of pre- 1980's fixed wiring to 100-type telephones, bellsets, terminal blocks, etc. With the 2-wire system, we are hoping to go over fully to jackpointing. This includes connections to fixed bellsets and electronic sounders, most of which are currently connected via screw or IDC terminal blocks. Ringing compatibility problems have been discussed in earlier Newsletters, but customers cannot easily disconnect these fixed wired items to check whether they are the cause when other less sensitive CPE fails to respond to ringing. By installing a jackpoint adjacent to each bellset or sounder and providing for easy disconnection, we hope to make it easier for customers to check out ringing problems for themselves and so avoid risking a call-out charge. It is recommended that all suppliers of bellsets and sounders make available suitable BT plug-ended connection cords as the preferred means of connection of their products. Customers purchasing them will then be able to plug them into any available socket without having to install additional wiring, as at present. This might lead to increased sales of sounders (and properly wired cordage), as a side benefit. However, when making such a change, remember that the plug wiring is connected to pins 5, 4 and 2 (there is a reversal within the jackpoint, which is connected at IDC terminals 2, 3 and 5). To minimise the risk of wiring faults being caused by the third wire, two wires only should be used. These are connected to pins 2 and 5 if a capacitor is fitted, or to pins 2 and 4 if no capacitor is fitted. Our preference is that all new bellsets and sounders be fitted with a series 1 µF capacitor so they can be plug-connected via pins 2 and 5 only, as for any other 2-wire CPE. 11. ELECTRICAL SAFETY TESTING As advised earlier, compliance with AS/NZS 3260 is the basic measure of the electrical safety of 230 V-powered CPE for Telepermit application purposes. AS 3108 is the appropriate standard for plug packs. The definition of modem safety testing requirements continues and, until the intention of AS/NZS 3260 and its impact under the Electricity Regulations are clarified, test laboratories are asked to carry out the full tests as advised in Newsletter No. 87. Test results will show which products do not meet the full requirements of this standard and we will have a better idea of how the industry is reacting to these issues. PTC 101: 1987 is now well out of date and Clauses C3, C4 and C5 of this specification are cancelled pending the imminent publication of the draft for comment of PTC 101: 1996. I expect this to tidy up testing and standards interpretation issues. A formal amendment to PTC 101, Issue 1, is not being issued at this late stage. While full compliance with creepage, clearance and insulation for 230 V operation would provide the maximum level of safety, the combination of conditions which could result in a hazard to the network or to a user are very improbable if the electrical strength of the device meets the 1500 V test. Certainly, there could be some degradation over time and this is mainly what the creepage and clearance requirements protect against. Nevertheless, the modem itself is working at Safety Extra Low Voltage (SELV), usually at 12 V d.c. It can be argued that the separately enclosed computer power supply is there to provide the necessary protection and isolation of the 230 V input. For electrical safety issues such as this, the Ministry of Commerce make the rules. I have thus asked them for advice on whether card modems should be regarded as 230 V-powered devices or SELV-powered devices. This is the key issue behind the varying interpretations of AS/NZS 3260 requirements. 12. "FAXABILITY" FAX MACHINES AND OTHER RINGING DECODER-EQUIPPED CPE I note that several fax suppliers are now advertising their products as "Faxability" capable. This applies to models which were Telepermitted before the service was introduced. While these machines no doubt operate to DA-4 ringing when it is received exactly at the specified cadence, this new feature is clearly a change in the network interface design. We thus require these machines to be tested under the defined tolerances of ± 10% on the nominal cadences and confirmation that they do not also react to the DA-2 and DA-3 cadences, which are to be introduced later this year. We are concerned that customers are not misled as to the capabilities of these machines or of any other decoders offered for sale to Telecom customers. If these devices do not detect distorted ringing or they fail to discriminate on other ring cadences, we are likely to suffer unnecessary customer complaints. In any cases where the CPE is found to be incapable of the necessary discrimination, the customer could face a call-out charge. If so, this is likely to be passed back to the retailer by the unhappy customer. We are reluctant to have our staff involved in arguments with customers about who is responsible for such problems and we certainly don't want our staff to spend a lot of time sorting out why a product is not working when the actual design was never proven capable of working to a particular cadence. Our aim is to show the actual cadences which a device is able to decode on the Telepermit label. This means that retailers, customers and staff are all aware of what that device is intended for, even if a problem arises at some time in the future when the User Manual is no longer available for reference. In the circumstances, those suppliers who have advertised or intend to advertise their products as capable of decoding our Distinctive Alerts are asked to arrange testing and submit their test reports to Access Standards. As an incentive to suppliers to sort this matter out quickly, those test results which are submitted for already Telepermitted products before 1 April will not be subject to a Telepermit variation charge by Access Standards. We will also provide the revised Telepermit label artwork free of charge for use on further production units and, where practicable, for fitting on units still held by retailers. 13. ORDERS FOR ACCESS STANDARDS DOCUMENTS We have had a string of "bad debts" recently where we have accepted telephone orders for PTC specifications and other documents in good faith, only to have them returned a few weeks later. We have also been told that documents were never received, or that no one in the company concerned had any knowledge of the matter. While we have been able to work on trust for many years, the problems caused by these claims are leading to a lot of extra work for our staff and for Telecom's accounts people. Even more annoying is to have documents returned after a few weeks, with the claim that they were ordered in error, when it is obvious that they have been pulled apart and then badly reassembled. We can't even re-sell the documents in these cases. We publish the titles and application of our PTC Specifications free of charge in our "Telepermit Overview". We also answer many questions from new "entrants" before an order is placed. It is thus usually quite clear to a potential Telepermit applicant what is required before a specification is ordered. We are therefore very reluctant to accept returned specifications and the need to go to the extra effort of arranging the necessary accounting adjustments. In the circumstances, we must now insist that telephone orders are followed up with a fax request. This request is to include a company order number and/or the name of the authorizing person so that should our Accounts people need to deal with other parties within the ordering company, there is a clear reference to the original order and the person concerned. As stated in clause 5.4 of PTC 100, we retain the right to decline a Telepermit if the applicant has outstanding debts. As far as possible we try not to apply this provision, but it is available where we get repeat or prolonged problems. DOUG BURRUS Manager Access Standards