TELECOM ACCESS STANDARDS NEWSLETTER NO. 146 January 2004 CONTENTS 1. POOR ADSL PERFORMANCE - COMMON CAUSES 2. ADSL LINE FILTERS - CONNECTING CPE 3. ADSL MODEM "RELATIVE PERFORMANCE" 4. RE-LOCATION OF TELECOM'S AUCKLAND BROADBAND TECHNOLOGY LABORATORY 5. TELEPERMIT APPLICATIONS - PROVISION OF EMAIL ADDRESSES 6. EMC COMPLIANCE - RADIOCOMMUNICATIONS NOTICE 2004 RETURN TO MAIN INDEX 1. POOR ADSL PERFORMANCE - COMMON CAUSES A number of exchange DSLAM performance records were recently checked and it was found that some customers are experiencing very slow data transfer and/or many ADSL re-starts each day. As part of our follow-up investigations, 20 of the customers who were suffering the worst performance were visited to determine the cause. In none of these cases was there any suggestion that their lines were particularly long or that they were experiencing any form of line interference. These site visits revealed that 18 of the 20 were "self-installs" where the customers had either not fitted line filters to ALL of their jackpoints to which POTS CPE was connected or that they had plugged the ADSL modem into the wrong (filtered") outlet of a 2-outlet line filter. The remaining 2 of the 20 had made wiring alterations since their service was originally commissioned by Telecom with a splitter mounted in the network termination. It is not suggested that the lack of line filters or their incorrect connection are the sole causes of any poor ADSL performance that our customers may be experiencing. However, the fact that most of the 20 customers visited were able to get much improved service as soon as additional filters (or, in some cases, Telecom-installed splitters) were fitted, indicates that these are probably very widespread causes of service problems. As stated in the information published by Telecom, at any premises where medical or security alarm systems are already connected to the line in "Line Break-in Mode", it is important that a splitter be fitted on the line side of those systems. In those cases where 4 or 5 line filters would be required, this will be a lower cost option in any case. Splitters also generally provide improved performance relative to several line filters, although they do restrict the modem to a specific jackpoint. When a new medical or security alarm is installed in premises that already have "JetStream" or other ADSL-based services, the installer may overlook the need for filtering the added wiring. In such cases, the alarm installer either needs to provide and connect a line filter as part of the installation work, or arrange for the customer to call in Telecom to install a splitter. Similarly, the addition of SKY digital services and the associated decoder for a customer with "JetStream" will require an additional line filter to be connected at the jackpoint provided for the decoder. All those concerned with alarm installations and SKY Digital installation work are asked to make sure they check whether a customer has "JetStream" or related ADSL-based services. If so, please take appropriate action to ensure that the necessary filters are fitted or that arrangements are made for the customer to have a splitter installed by Telecom. Modem and line filter suppliers are asked to check their documentation to make sure that it clearly explains the need to connect a filter at each jackpoint to which a non-ADSL device is fitted. 2. ADSL LINE FILTERS - CONNECTING CPE Many different ADSL line filters have now been granted Telepermit. These vary from "pigtail" or plug and cord connected units to moulded plastic devices almost identical to double adapters. Where there is a single filtered BT socket provided for the POTS CPE, connection is relatively foolproof. The main issue is to have a filter connected on the line side of each POTS CPE item, as explained above. Some line filters provide either two BT sockets or one BT and one RJ 12 socket. These are typically marked "Phone" and "ADSL". The RJ versions were permitted for use with any modems that are provided with line cords terminated with RJ 12 plugs at both ends. However, these filters can be a trap for some customers with ADSL modems having BT plug-ended line cords. Should they purchase a line filter with the two types of socket, it is likely that the ADSL modem could be plugged into the BT socket which is, of course, the filtered one. As a result, their high speed service is seriously degraded. We would have expected this situation to be obvious to most customers, but were surprised to find that although some of those users mentioned in item 1 above were suffering quite poor service, they had not even bothered to report this to Telecom. Again, it seems that not only our JetStream Help Desk staff, but also modem suppliers and retailers may have to check the "obvious" when any customers complain that recently-purchased ADSL modems are not working very well. 3. ADSL MODEM "RELATIVE PERFORMANCE" An enquiry was forwarded to us in December with respect to Telecom's charging for a service visit to a customer's premises as the result of a complaint over poor ADSL performance. Finding no apparent network fault, the Telecom contractor checked the customer's line with his own laptop PC, using a Telecom-supplied Nokia M1122 modem. He achieved acceptable up-load and download speeds with this equipment, even though the line was relatively long. This test indicated that the cause of the problem was within the customer's own equipment, so the standard service visit charge applied. It was suggested that because the customer's own modem did not perform as well as the Nokia M1122 on such a long line, modems of that particular type should not have been granted a Telepermit. This enquiry raised the need to clarify what Telepermit really means. It is simply "Telecom's agreement to a customer connecting equipment of a particular type to its network". * It is NOT an endorsement of the product; * It is NOT some form of guarantee by Telecom that the product will work correctly under ALL network conditions; * It is NOT some form of assurance that the product will work correctly in conjunction with ALL other types of Telepermitted CPE. The Telepermit is based on compliance with a set of minimum requirements, as published in Telecom's PTC specifications and related Standards. These include compliance with the relevant safety standards for the particular class of product. In the case of ADSL modems, the relevant ITU Recommendation clearly covers the fall-off of data speed with increasing line length and loss, the presence of interfering factors, etc. Ideally, every modem would provide identical performance, but this simply does not happen and differences in performance can certainly be expected if a $100 modem is compared directly with a $500 modem. Above all, most modem suppliers would consider Telecom unreasonable if we were to grant permission to connect only the top performing modem types, especially when the majority of our lines are of only 2 km or less from our exchanges. PTC 270 stresses the need for modem suppliers to support their products and this includes monitoring service problems reported by their users. Where there is any concern that a specific type of modem is "weak" on long lines, one form of support is to ask the retailer to look on the Telecom website to check the likely performance of the prospective customer's line (see http://www.telecom.co.nz/chm/0,5123,202905-202534,00.html ) 4. RE-LOCATION OF TELECOM'S AUCKLAND BROADBAND TECHNOLOGY LABORATORY As advised in Newsletter No. 145, the Telecom test laboratory that was previously installed in the Mayoral Drive Building in Auckland is now being re-located. Part will go into what was known as the Technology Solutions Laboratory in Telecom's Tory Street complex in Wellington. Other parts will be located at Wellington Central Telephone Exchange. In case there is any confusion over the street address, the Wellington laboratory has recently been re-named "Network Integration Laboratory". It is located at the Telecom Centre, 49 - 55 Tory Street, Wellington. The new contact details will be published on our website in due course. 5. TELEPERMIT APPLICATIONS - PROVISION OF EMAIL ADDRESSES It is recommended that all applicants for Telepermits include their email addresses - preferably making sure that the wording is legible! We have provided a panel on the application form for these details, but find that it is not always used. From our viewpoint, we can much more easily acknowledge receipt of an application or request any follow-up information by email than via mail or fax. For the applicant, our prompt acknowledgement may alleviate any concerns that the documents have gone astray. 6. EMC COMPLIANCE - RADIOCOMMUNICATIONS NOTICE 2004 Further to the summary of EMC compliance requirements given in Newsletter No. 141, the Ministry of Economic Development has recently published a series of 2004 Radiocommunications Notices to up-date those published on their website for the May 2003 regulatory changes. The basic requirements of marking a C-tick and a Supplier Code Number (SCN) on CPE products introduced since May 2003 remains unchanged. However, there are some exceptions, which include cellphones and, possibly, pagers. An important point to note is that battery chargers and power packs introduced since May 2003 do need to be marked with a C-tick and the relevant manufacturer's or importer's SCN. In view of the EMC framework being aligned with that of Australia, it is permissible to use an Australian C-tick on products supplied in this country provided that the NZ importer is directly related to the Australian SCN holder and does so with that party's agreement. See http://www.med.govt.nz/rsm/standards for further details. DOUG BURRUS Manager Access Standards