TELECOM ACCESS STANDARDS NEWSLETTER NO. 89

April 1996
CONTENTS
1. NEW CHARGE STRUCTURE FOR TELEPERMIT APPLICATIONS
2. PTC 200 & TNA 102
3. NEW BUILDING CABLING STANDARD
4. USE OF RJ 45 PLUGS FOR CPE LINE CONNECTIONS
5. ELECTRICAL SAFETY TESTING
6. NEW AMPS ALL - DIGITAL CELLPHONE SPECIFICATION
7. TELECOM CELLULAR NETWORK INTRODUCING 7-DIGIT NUMBERS
8. CPE CALLER DISPLAY CAPABILITY
9. SPECIAL FACILITIES FOR THE DEAF AND HARD OF HEARING
10. NETWORK DIALLING TIMEOUT INCREASE
11. STAFF CHANGE
Attachments
RETURN TO MAIN INDEX



1. NEW CHARGE STRUCTURE FOR TELEPERMIT APPLICATIONS
As announced in November 1995 (Newsletter No. 85), we are revising our charging structure for Telepermit applications from 1 April. Rather than go into detail within this Newsletter, the full price schedule is published in Issue 18 of the "Telepermit Overview", a copy of which is provided with this Newsletter.

This latest edition includes a number of other additions and amendments to the main text, but only those relating to PTC and TNA Specifications are mentioned in the following article.



2. PTC 200 & TNA 102
The Overview includes references to the new specifications, PTC 200 and TNA 102. These are not quite ready for publication, but they are expected to be published in April. PTC 200 is listed in the Overview in place of the draft of PTC 202, which was issued in December 1994. PTC 200 also replaces PTC 211 and PTC 212 by incorporating their requirements within additional Sections of this new general specification. Sections of PTC 200 now cover requirements for Caller Display devices and Distinctive Ringing decoders, which were published as drafts last year. New Sections cover cordless telephones, telephone headsets, and other devices, formally publishing the processes and requirements that have evolved over the past few years. Few actual changes in requirements have been made and those that have been made have already been covered either in these Newsletters or in drafts already issued.

Although the new Specifications are not immediately available, we will accept orders for them now. Both are to be published in our new A4 loose leaf format. The individual prices will be $120 for PTC 200 and $60 for TNA 102. These will normally be supplied unbound.

Since both specifications are needed by Telepermit applicants and we are anxious to get them launched, we are making a "Special Introductory Offer" through till the end of June. The introductory price for the pair is $170, complete with one of the white Telepermit binders we offered for sale in March/April last year at $15 each. If the binder is not required, the price for the two documents is $160. Where a reader is replacing the draft of PTC 202, Issue 2, the combined price will be reduced by the $90 they originally paid. All the above prices include GST and postage.

The A4 binders we provide are large enough to fit the "Telepermit Overview" and several other PTC Specifications. These could include PTC 100 and PTC 101 when they are re-published. As such, readers

will be able to "customise" a package of Telepermit documentation within the single binder. Above all, the new system will avoid the drawbacks of the present amendment system. Future additions and amendments will be issued as complete replacement pages or Sections, as required. Handwritten or "glued-in" amendments should no longer be necessary.



3. NEW BUILDING CABLING STANDARD
AS/NZS 3080 is now available from Standards New Zealand at a price of $87.98 to SNZ members or $109.97 to non-members. As mentioned earlier, this standard is essentially ISO/IEC 11801: 1995, but with some Australia and New Zealand supplements.

The new standard complements other AS and AS/NZS standards on building cabling, some of which are already available. Others are due in the near future. The aim of the joint AS/NZS working group is a comprehensive set of cabling standards that cover everything from building accommodation, pathway and space provision at the architectural design stage, through cabling design, installation and testing, to ongoing recording and management.

The overall outcome should be a building cabling infrastructure with at least a ten year service life, capable of supporting not only all current data and voice services, but also those new services currently under development. In fact, it is reassuring to hear that much of the new high speed LAN development is being based on the 100 MHz capabilities of the 4-pair Cat 5 UTP and multi-mode fibre cables specified by this Standard.

Standards New Zealand is proposing a series of public seminars to launch the new standard. Tentative timings are May 13 at Auckland, May 14 at Wellington and May 15 at Christchurch. The current plan is to have afternoon sessions only, probably with registration starting at 1.30, and the actual seminar going from 2.00 - 5.00 pm. There is considerable interest from the main cable and hardware suppliers and many of these organisations are assisting Standards New Zealand by sponsoring the seminars. Telecom and TUANZ will also be contributing.

The seminar will give an overview of the standard, and then go on to discuss the design, installation and testing of generic cabling. For details of the charges and actual venues for these seminars, telephone Seminar Services, Standards New Zealand on (04) 498 5990 or fax them on (04) 498 5994



4. USE OF RJ 45 PLUGS FOR CPE LINE CONNECTIONS
With the publication of AS/NZS 3080, the RJ 45 socket is formally defined as an accepted New Zealand Standard for commercial buildings. I should remind CPE suppliers that Telecom has no objection to 2-wire connected telephones, faxes, etc, being fitted with an RJ 45 plug. The only proviso is that the Telepermit holder for that product accepts that such a change does not conflict with product warranties or other Telepermit compliance requirements.

While there will be a tendency for some installers to do an "on-site" modification by simply chopping off a BT plug and connecting a 6-way RJ 11 or RJ 45 plug, this can prove unreliable. The preferred arrangement is for the CPE supplier to provide optional factory-assembled BT or RJ 45 plug-ended line cords, which are confirmed to suit the CPE concerned.

NOTE: There is considerable doubt as to the long term effectiveness if an RJ 11 6-way plug is used with an RJ 45 socket. The problem is that the outer shoulders of the RJ 11 plug can over-stress the outer springs of the socket. As a result, the socket may prove to be of doubtful reliability when it is finally needed for use with an RJ 45 plug. It is far better to fit an RJ 45 plug to CPE required for a modern generic cabling system using RJ 45 sockets.

3-wire connected CPE will need a suitable "master" adapter when used in a generic cabling installation, but this can be avoided by specifying 2-wire connected CPE from the outset.



5. ELECTRICAL SAFETY TESTING
The issue of electrical safety testing of modems and the interpretation of AS/NZS 3260 has been dealt with in the past three Newsletters. As mentioned in Newsletter No. 88, the modem itself is working at Safety Extra Low Voltage (SELV),usually at 12 V d.c. The separately enclosed computer power supply could be considered to provide the necessary isolation between the 230 V input and the SELV supply. Under the terms of our current standard, a key issue is whether modems are to be regarded as 230 V-powered devices or SELV-powered devices.

Since asking the Ministry of Commerce for a formal ruling on this matter, I have done further research on these safety and testing issues. I received valuable assistance from Standards New Zealand staff, who supplied me with copies of the latest IEC TC 74 working group papers, and the position is now becoming a little clearer.

Because this matter is of interest to most suppliers of modems and other PC card devices, I have gone to some trouble to explain the position in detail. This explanation is presented as an Appendix to this Newsletter, so that it can also be used as a "standalone" document.

The net result of this research is the proposal that, for Telepermit purposes, Telecom should again accept safety tests along the lines originally published in PTC 211 and PTC 212. In due course, these will be incorporated into the proposed 1996 edition of PTC 101. However, this proposal may be revised as the result of any rulings on safety requirements by the Ministry of Commerce. In the meantime, I would appreciate comments from the industry and test laboratories. While modems have been the primary issue of this investigation, the same principles apply to other products as regards separation of the network from SELV supplies in the CPE and separation of the network from the local earth at the customer's premise.



6. NEW AMPS ALL - DIGITAL CELLPHONE SPECIFICATION
The dual mode analogue/digital cellphones currently in service on the Telecom cellular network use the same analogue control channel as the all-analogue telephones even though they digitally encode speech signals. Developments in the AMPS mobile world have now led to the publication of EIA/TIA specification IS 136. This covers cellphones which digitally encode speech and also use a digital control channel.

Telepermit requirements for the "all-digital" product will generally follow the lines already published in specifications PTC 252 and PTC 254. We will shortly be publishing PTC 255 to specifically deal with issues raised by this new class of product. All three specifications are based on the need for a local supplier to submit FCC test reports, the name of the manufacturer, the FCC ID, software version equipped and other details. Samples of the product are then field tested by Telecom and, if all goes well, a Telepermit is granted.

As with the present generation of AMPS cellphones, we are particularly keen on having CTIA (Cellular Telephone Industry Association) Certification as an endorsement of a product. This certification provides an assurance that adequate security and other features have been incorporated into the design. Partly to encourage suppliers to gain CTIA Certification, field testing of samples by Telecom cellular network engineers is currently set at $500 for cellphones with that certification, but $5000 for those without it. This difference in fees also reflects to some extent the amount of additional field testing needed to prove compliance with our network.

We intend to follow this established practice with the new all-digital models. However, we have no field experience of the particular characteristics of IS 136 mobiles at this early stage. For assured performance, test arrangements need to be defined along the lines of those of the CTIA. The test programme will take some time to organise. It is also expected to involve a good deal more testing than we currently carry out. The CTIA currently charge around US$ 30 000 for their tests and our programme could end up at a comparable level. In the meantime, if any local suppliers do have IS 136 cellphones available, we would be keen to do some initial trials with them on the Telecom network.

For IS 136 mobiles, PTC 255 will provide the options of either gaining CTIA Certification before applying for a Telepermit and paying the $500, or waiting for the Telecom test programme to be defined and paying an as yet undefined charge. Needless to say, we strongly recommend that manufacturers of these products go for CTIA certification, as this is recognised by AMPS network operators worldwide.

We will issue PTC 255 as a "draft for public comment" in the usual way. This will give local suppliers the opportunity to provide their input. It will also give Telecom the opportunity to get some field experience with the first product samples before we publish the confirmed Issue 1 version.



7. TELECOM CELLULAR NETWORK INTRODUCING 7-DIGIT NUMBERS
Telecom's mobile network will soon be providing new customers with 7-digit cellphone numbers. These will be in the "025 2xx xxx" series. All of Telecom Mobile's existing 6-digit "025" numbers will remain unaltered.

This information is published for CPE suppliers and their service staff, in case this new number group affects existing installations. Some PABX systems may include cellular network numbering details in their programming. A test number has been allocated for checking system programming. The test number is "0252 220 000". Test calls are charged at normal PSTN - cellular rates.



8. CALLER DISPLAY CAPABILITY
Further to the article in Newsletter No. 88 concerning claims that fax machines are "Faxability" capable, I note a recent advertisement for a fax machine claiming to be "Caller ID" ready. The same basic principles apply - before making such claims to be compatible with new Telecom services or implying such compatibility with our network interface, we require suppliers to show us test results to confirm this capability under our network interface conditions.



9. SPECIAL FACILITIES FOR THE DEAF AND HARD OF HEARING
Quite a large number of telephones, including Telecom's payphones and new rental phones, now provide inductive couplers for hearing aids which have a "T" setting. Unfortunately, the availability of this coupling facility is not always apparent to users. A standard symbol was adopted by the World federation of the Deaf during their meeting in 1980. This is now published in ITU (CCITT) Rec. E.121, in NZS 4121: 1985 and in AS 1428.2: 1992.

It consists of a stylised ear with a diagonal slash on a plain square background. Preferably, the ear and bar are to be shown in white, with the square background in blue. The blue is colour B21, Ultramarine, to AS 2700. The symbol is already used on Telecom's public payphones and by TV New Zealand to indicate that a programme has teletext sub-titles provided to assist the hard of hearing. Although the colours are defined in the Standards, for telephones and other CPE items, it will generally be more convenient to have the symbol in white or black with the plastic colour forming the background.

Unlike those of the FCC and AUSTEL, Telecom PTC specifications do not mandate the provision of hearing aid coupling facilities. We regard these as marketing features and consider it would be unreasonable to make them a condition for the grant of a Telepermit for all types of telephones. Nevertheless, their provision is recommended, especially for any models of telephones which are expected to go into widespread use.



10. NETWORK DIALLING TIMEOUT INCREASE
The interdigital timeout in our NEAX exchanges was changed from 4 to 10 seconds some months ago. With a 10% tolerance, this means that a caller could pause for up to 11 seconds between dialling successive digits. This was done so that callers could pause while dialling a long number without having the call dropped. The change was not announced at the time, as it was not seen as relevant to CPE operation.

It has recently been reported that some call loggers or call detail recorders used with PABX installations have not been recording calldetails correctly. This can arise where their inter-digital timeout or total time to monitor all the digits dialled is shorter than the network timeout. As a result, the logging device may wrongly assume that the call was not completed.

Those parties maintaining or managing call loggers or call detail recorders are advised to ensure that their equipment is set to ensure accurate data collection for all dialled numbers, whether they are dialled quickly or slowly. This means that they must accept DTMF interdigital pauses in the range 40 ms to 11 secs. The same maximum applies to decadic dialling.



11. STAFF CHANGE
I am sorry to report that Jenny Hok is leaving us in mid-April. Jenny has served Access Standards well over the past seven years and we will miss her cheery smile. We are currently looking for a replacement. In the meantime, correspondence can be addressed to Access Standards rather than direct to Jenny.




DOUG BURRUS
Manager
Access Standards



Attachments:

Appendix No. 1 "Electrical Safety Testing of PC Card Modems"

"Telepermit Overview" - Issue 18

APPENDIX No. 1

ELECTRICAL SAFETY TESTING OF PC CARD TELECOMMUNICATIONS DEVICES

INTRODUCTION
The following Appendix covers the issue of electrical safety testing for modems and other devices which are connected to the Telecom network, to CPE SELV power supplies and/or to a customer premises earth. NZECP 3 specifies AS/NZS 3260: 1993 with Amendments 1 & 2 as the appropriate safety standard for such information technology equipment. For New Zealand applications, this Standard is essentially equivalent to the international version, IEC 950: 1991, with its Amendments 1, 2 and 3.

There has been a lot of concern about the interpretation of AS/NZS 3260 in relation to New Zealand regulatory requirements and Telecom's Telepermit requirements. Work done by AUSTEL and by the testing laboratories in Australia came to the conclusion that PC card modems should be classed as "Pluggable equipment Type A". As a result, they should be regarded as 230 V-powered devices for compliance testing purposes. However, most modems sold and used in New Zealand were originally designed for use on the North American market, which uses 110 V power systems. As a result, they do not meet the current Australian safety requirements. The question is whether such devices provide the required level of safety in accordance with the New Zealand Electricity Regulations.

TELECOM'S POSITION
In researching this issue, I have been very conscious of the fact that Telecom's safety requirements have never complied with the current Australian interpretation of AS/NZS 3260. Notwithstanding this, hundreds of thousands of modems have been put into service without any significant problems. This practical experience indicates that these devices do meet the requirements of Electricity Regulation 59. This requires that "there is no significant risk of injury or death to any person, or of damage to any property, as a result of the use of electricity".

Earlier products complying with PTC specifications, but not meeting the current Australian interpretation of AS/NZS 3260 are still on sale and connected in large numbers to Telecom's network. To refuse Telepermits to new products which meet the same PTC requirements would be unfair to the suppliers concerned. Around a hundred modem Telepermit applications alone are being received each year and strict adherence to the Australian interpretation would block a wide range of new products.

OUTLINE OF CURRENT STANDARDS ISSUE
A PC card modem operates primarily at Safety Extra Low Voltage (SELV). The separately enclosed computer power supply is intended to provide the necessary isolation between the 230 V input and this SELV supply. In addition, the network connection of the modem operates at Telecommunications Network Voltage. Safety isolation is required between the network voltage and SELV, and between the network voltage and the computer earth. This isolation has to satisfy the requirements of Reg. 59.

The associated computer is connected to the 230 V supply and its power cable could be incorrectly terminated, such that the phase and earth are transposed. This would result in 230 V being applied to the earth and SELV supplies. This scenario supports the Australian decision to also class the modem as "Pluggable equipment Type A". Countering this, the computer would not be operational, so such a transposition would be immediately apparent. Also, most computers use moulded plugs and the cables are not subject to regular movement or rough usage. Plug replacement is thus not a common event.

If it is classed as "Pluggable equipment Type A", the modem has to meet the "creepage, clearance and thickness of insulation requirements of Supplementary insulation for a 230 V primary circuit". These requirements are in addition to the electrical strength or impulse test that would otherwise be required to confirm adequate isolation between the TNV and SELV/local earth. Clause 6.3.3 of AS/NZS 3260 refers.

INTERNATIONAL STANDARDS DEVELOPMENTS
Since AS/NZS 3260 was published, the IEC TC 74 committee has been working on Amendment No. 4 to the base standard, IEC 950: 1991 (this is now close to publication). Concurrently, they are also working on the next edition - currently termed "Issue 3". However, this might not be published for some time.

Amendment No. 4 incorporates several amendments to Section 6 of IEC 950, which deals with "Connection to telecommunications networks". The working group papers for Amendment No. 4 are now at the public discussion stage, so the changes are very likely to be adopted by the IEC. Changes which relate to safety requirements for card modems are as follows:-

The category "TNV" is to be divided into three separate classes:-

TNV-1 covers circuits whose normal operating voltages do not exceed the limit for an SELV circuit under normal operating conditions, but which may be subject to transient overvoltages from a telecommunications network.

TNV-2 covers circuits whose normal operating voltages exceed the limit for an SELV circuit under normal operating conditions, but which are not subject to transient overvoltages from a telecommunications network.

TNV-3 covers circuits whose normal operating voltages exceed the limit for an SELV circuit under normal operating conditions, and which may be subject to transient overvoltages from a telecommunications network.

By way of explanation, an SELV circuit is a secondary circuit (one isolated from the mains supply by a transformer) so designed and protected that, under normal and single fault conditions, its voltages do not exceed a safe value. In this respect, any voltage not exceeding 42.4 V peak or 60 V d.c. can be considered to be within the SELV range.

Analogue terminal equipment connected to Telecom's network can be considered to be working at TNV-3.

Clause 6.2.1.2 and Table 19 of Amendment No. 4 requires that SELV circuits be separated from TNV-3 circuits by Basic Insulation and by the tests defined in clause 6.4.1, although other solutions are not excluded. Clause 6.4.1 calls up the electrical strength or impulse tests of clause 6.4.2. As a result, PC card modems need to be tested either with 1.5 kV d.c. impulse test to clause 6.4.2.1, or by a 1.0 kV a.c. rms voltage electrical strength test for 60 seconds in accordance with clause 6.4.2.2. In neither case is breakdown permitted, nor shall the current flowing exceed 10 mA. "Breakdown" is considered to have occurred when the current which flows as a result of the application of the test voltage rapidly increases in an uncontrolled manner.

The separation between TNV and earthed conductive parts required by AS/NZS 3260 is one of the current interpretation problems, but Amendment No. 4 drops the present clause 6.3.3 requirement for Supplementary insulation. This clause also clarifies the position with respect to surge suppressors that bridge the insulation. These are required to have a minimum d.c. sparkover voltage of 1.6 times the upper voltage of the working voltage range of the equipment and shall not be damaged during the electrical strength tests of the insulation. A note to clause 6.4.2 specifically states that "There is no Clearance, Creepage Distance or distance through insulation requirement for compliance with 6.4.1".

PROPOSED TELEPERMIT REQUIREMENT
It is not normally acceptable to make use of a draft standard before it is formally adopted, but this seems to be the only practicable alternative to refusing Telepermits and keeping useful products off the market.

The granting of a Telepermit indicates Telecom's permission to connect a product to its network. Whether a product meets all the legal requirements for sale and use in New Zealand is the responsibility of the supplier of that product and the Ministry of Commerce has been asked to clarify the safety requirements. The IEC proposals align with our original test requirements and, as such, support retention of those requirements until such time as the Ministry of Commerce might give a ruling to the contrary.

In the circumstances, it is now proposed that the current "creepage, clearance and thickness of insulation requirements of Supplementary insulation for a 230 V primary circuit" of clause 6.3.3 of AS/NZS 3260 be dropped for Telepermit purposes. PTC 101: 1996 will be based on the final outcome of these deliberations.