TELECOM ACCESS STANDARDS NEWSLETTER NO. 155

May 2005

CONTENTS
1. PTC 270 CHANGES: TR-048 AND ADSL MODEM REQUIREMENTS
2. PTC 220 DEVELOPMENTS
3. LEGAL ASPECTS OF TELEPERMIT COMPLIANCE
4. CUSTOMER PREMISES WIRING AND POWER OVER ETHERNET
5. PARALLEL IMPORTING AND EMC COMPLIANCE
APPENDIX: TELEPERMIT REQUIREMENTS UNDER NEW ZEALAND LAW
RETURN TO MAIN INDEX



1. PTC 270 CHANGES: TR-048 AND ADSL MODEM REQUIREMENTS

a. Ringing and on/off hook transients
There are several operational parameters potentially impacting on ADSL modem performance that are not covered in the present version of PTC 270. We have generally assumed that modems offered for sale here have been in use in other countries and that basic operating features have been confirmed in service before these devices are submitted for Telepermit in this country. For example, we had assumed that all ADSL modems would be unaffected by incoming ringing or other CPE on the same line going on-hook or off-hook in line with the requirements of. Annex A of ITU-T G.992.1. Recently, Telecom has become aware that a small percentage of end-user customers appear to experience frequent “re-starts” with some modem types. This could be due to non-compliance with these two requirements.

To check this possibility, we intend to make more or less immediate changes to PTC 270 to cover some of these parameters.

b. Formal Inter-operability tests
Another issue is to make better use of existing test reports. Where some operating parameter has already been tested, it should not be necessary to re-test it here. For example, the DSL Forum has an inter-operability test process covered by their specification TR-048. This has particular relevance in our network, which now uses mostly Alcatel DSLAM’s (formally designated as “Alcatel 7300 ASAM R4.2.22”) as the network end of each ADSL-equipped line. In carrying out their DSLAM development for future hardware and software releases, Alcatel uses DSL Forum TR-048 “ADSL Interoperability Test Plan” based tests with a wide range of officially agreed reference modems.

Telecom’s initial comparison between its list of Telepermitted ADSL modems and Alcatel’s agreed official modem list indicates that only some of modems appear to be on both lists. This direct comparison of make and model designations may be misleading, of course. Often, a nominally identical product may be made by the manufacturer for a range of different brands, each of which adopts a market specific model name or number. As a result, it may be that more modem types sold here have actually passed the TR-048 tests and are already on the Alcatel agreed official modem list as a different brand and model.

c. ADSL 2 capable modems
The introduction of ADSL 2 capable Alcatel DSLAM’s and modems brings even more importance to this question of interoperability confirmation. Alcatel have tested all officially agreed ADSL 1 modems to make sure they will interoperate correctly with their ADSL 2 linecards and pass TR-048. Nevertheless, it is possible that at least some of the 180 or so different types used in this country may fail when connected to our new ADSL 2 linecards.

As a preliminary step in the assurance process, we have advised suppliers of “ADSL 2 capable” modems to take some care in their advertising – just in case these products prove to have problems when connected to the new Alcatel DSLAM’s.

The question, of course, is “which modems have been tested to DSL Forum TR-048 at an approved Independent Test Laboratory or successfully tested against Alcatel’s officially agreed modem test list?”


d. Request for enquiries to manufacturers
Only the DSL modem manufacturers know what brands and models are equivalent to one another across the markets they serve, so we are now asking local modem suppliers to find out whether their manufacturer has conducted TR-048 tests on the modems that have been supplied to our market. This seems very likely, as many overseas countries insist on seeing a TR-048 compliance certificate from a DSL Forum approved independent test laboratory before they will permit connection of any new modem type.

In some cases, these tests may have been carried out unsuccessfully. If so, it would be advisable for local suppliers to find out what aspects have failed these tests.

e. Precautionary moves
Because any cases of service interruption to our customers due to DSLAM changes are regarded seriously by Telecom, we expect to be taking a number of precautionary steps to avoid problems. However, with around 180 different types of ADSL modem currently in service, we will be formally seeking the co-operation of the all modem suppliers.

As a first step, Telecom requests ADSL modem suppliers to make these enquiries and advise Access Standards whether or not each specific model has been certified to TR-048 and, if so, what technically directly equivalent brand and model designation applied to the modem that was actually tested? We will be writing directly to most suppliers to make this request, but would appreciate such enquiries being made as the result of this newsletter article before we have actually sent out these letters.

More on this question of inter-operability assurance will be published in future Newsletters.


2. PTC 220 DEVELOPMENTS

The testing and verification of VoIP devices and add-ons to digital PBX systems continues to be a problem. There has been some comment on the approach taken in PTC 220 and subsequent Newsletter articles, but it must not be forgotten that the key purpose of Telecom’s Telepermit system is to ensure that all CPE is compatible with the Telecom network and that its performance complies with Telecom and ITU-T design standards.

It might not be realised, but we really do read the test reports submitted in support of a Telepermit application. If we cannot understand the results or the conditions under which they were measured, we will ask questions until we are satisfied that the product does comply.

We are seeing a lot of VoIP system test reports that indicate compliance of a specific combination of terminal equipment, but where the actual transmission settings are not defined. Further complications arise where it seems clear that different settings may have been used for different tests, such that there is no one lot of settings that satisfies all PTC 220 requirements.

Actual installations in New Zealand, using some of the equipment Telepermitted before we became aware of these problems, have resulted in a range of performance variations. These have come about because the installers were not given clear instructions and had to do their best to determine the best compromise settings by a process of trial and error.

The key message for prompt processing of any VoIP Telepermit application is a block diagram of the equipment connected and a clear statement of the “one lot of settings” that have been used during all of the testing. We also require assurance that these same settings will be communicated to installers of the equipment that is being connected to the Telecom network.  


3. LEGAL ASPECTS OF TELEPERMIT COMPLIANCE

Although our Telepermit system has been in operation since 1987 and seems well-established, we still get cases of telecommunications products being offered for sale without Telepermit. Most cases arise with newcomers to the local CPE market, especially those new to this country and its laws.

Appendix No. 1 to this Newsletter gives an explanatory summary of the legal situation as far as the sale of CPE products is concerned. This mentions also EMC compliance, part of the Ministry of Economic Development’s role, but an important aspect of many types of CPE that must not be overlooked. The key point, of course, is that formal testing of a new product to Telecom’s relevant PTC Specification gives the local supplier assurance that the product does “fit” with the Telecom network and that it can be expected to work properly in the local environment.

While we aim to align local network interfaces with international standards as far as practicable, there are still differences between the Telecom network and those overseas and it is important to all concerned that a new product does not give rise to a rash of customer complaints because some feature does not work as expected.


4. CUSTOMER PREMISES WIRING AND POWER OVER ETHERNET

The question of cable versus radio for in-home telecommunications systems is getting even more interesting as radio devices reduce in cost and the latest types of wiring increase in speed capability.

For an existing home, where additional or replacement wiring is difficult to install, radio offers the easiest solution for today’s home LAN and standard POTS requirements. However, it there is now a trend for many homes to cater for a wider range of wired services. These include such aspects as security cameras and building automation, in addition to fairly extensive “Cat 5 or better” cabling for LAN operation and co-axial cable for television distribution.

Power over Ethernet (PoE) was mentioned in Newsletter No. 152, soon after the IEEE 802.3af standard was ratified. A recent ADC Krone presentation mentioned that Power over Ethernet devices are already becoming common overseas and stressed the point that the RJ45 socket could be regarded as the first “universally standardised power outlet” for low consumption devices (those nominally taking less than 13 W at 50 V dc).

Avoiding the need for a 230 V outlet in close proximity to every device connected to the wiring system was the primary aim, but added advantages are that the “centralised” power unit also provides “clean” dc power (free of mains transients and harmonics generated by other 230 V powered equipment in the home). Some PoE power units can also provide the option for battery back-up to give an uninterruptible power supply (UPS), making service continuity of the associated equipment independent of the mains supply for at least a limited period.

At this stage, there seems to be a “chicken and egg” situation, where relatively few PoE power supplies are about as few equipment items yet use PoE. However, the opportunity is there to make better use of this technology and the benefits it offers.

As recommended in previous Newsletters, installing plenty of cabling in a new home at the pre-lining stage should be a good investment in the long term, despite the availability of radio solutions. The amount of cable and the range of services it can and will be called on to support all justifies a generously proportioned “Home Distributor” with space for not only the cables and their terminating/cross-connecting hardware, but also for the 230 V outlets and power supplies needed to drive the associated terminal equipment. Any back-up batteries considered necessary add even further to the space requirements.


5. PARALLEL IMPORTING AND EMC COMPLIANCE

The Radio Spectrum Management division of the Ministry of Economic Development published a business update on this issue in April. This should be of particular interest to parallel importers of telecommunications CPE in general, not just that which intentionally uses the radio spectrum.

The URL for this information is http://news.business.govt.nz/news/rsm/article/2174

The Ministry, like Telecom, requires parallel importers to independently confirm a product’s compliance with local requirements (PTC Specifications in Telecom’s case).

The primary message is that a parallel importer cannot assume that because a product is already covered by a Telepermit or C-Tick held by the “main importer”, an apparently identical article purchased in another market will automatically meet local requirements. Manufacturers often customise their products for different markets such that software will be changed to meet each market’s special requirements or individual components may be omitted or changed in an effort to minimise production costs.



Doug Burrus
Manager
Access Standards


APPENDIX: TELEPERMIT REQUIREMENTS UNDER NEW ZEALAND LAW

Under Section 106 of the Telecommunications Act 2001*, it is illegal to connect devices to a Telecommunications Network without the agreement of the Network Operator. In the case of Telecom, that agreement is indicated in the grant of a Telepermit to those devices which meet the requirements published in Telecom's PTC Specifications.

By selling non-Telepermitted products, Telecom considers that a supplier to be contravening the Telecommunications Act, by aiding the purchaser to breach that Act. This action may be subject to court action. The advertising or offering for sale of non-Telepermitted devices also falls within this category.

Equipment suppliers are no doubt aware that a great proportion of their potential customers are also likely to be customers of Telecom and that Telecom’s service to its customers is provided in accordance with Telecom's standard terms.  These terms include a requirement to connect only Telepermitted equipment.

Telecom requires suppliers to immediately cease selling or installing any products, for which a Telepermit would be required, but which do not hold valid Telepermits. No further units should be sold until such time as the products concerned have been tested and granted a Telepermit.

All such products are to be tested by an accredited laboratory (see Telecom Access Standards website www.telepermit.co.nz for details of test labs). They can be approached regarding the costs and timing of tests. By gaining the necessary Telepermits, suppliers can offer these products for unrestricted sale with confidence that the product is compatible with the Telecom network.

Most electronic products, including telecommunications CPE, are subject to the requirements of the Radiocommunications (Radio) Regulations (managed by the Ministry of Economic Development) before they are offered for sale. The Ministry’s requirements are published on their website www.med.govt.nz/rsm

All 230 V-powered equipment is also subject to the Electricity Regulations, which call up the appropriate safety standards.

Where suppliers are purchasing from a third party, any telecommunications equipment that has no Telepermit label, that party should be advised of their legal obligations. No further products of that type should be purchased until the third party has complied with those obligations.

Offering for sale any item of equipment that may not be lawfully connected to a network may also breach the Consumer Guarantees Act 1993 and/or the Fair Trading Act 1986.

In view of the above legal issues, suppliers are advised to seek legal advice in any situations where they are in doubt about their obligations.

NOTE: This is a general guide only and not a substitute for obtaining your own legal advice.


* This matter was previously dealt with under section 6 of the Telecommunications Act 1987.