TELECOM ACCESS STANDARDS NEWSLETTER NO. 120 April/May2000 CONTENTS 1. "JETSTREAM" ADSL PROGRESS 2. "VOICE OVER PACKET" PABX TRUNK SUPERVISION 3. "SYNCHRONISED" CALLING 4. PREMISES WIRING: SAFETY AND RELIABILITY ISSUES 5. NOTIFICATION OF NEW OR ADDITIONAL ESN-SERIES FOR CELLPHONES 6. USE OF TELECOM "GREEN PIPE" 7. "BLUETOOTH" RADIO DEVICES 8. VACANCY FOR AN ENGINEER IN ACCESS STANDARDS RETURN TO MAIN INDEX 1. "JETSTREAM" ADSL PROGRESS Despite our best attempts to define and publish requirements for ADSL CPE intended for operation with Telecom's "Jetstream" service, launched last June, we continue to have difficulty defining "firm and permanent" interface details. As explained in Newsletter No. 114 (June 1999), Telecom's commercial service was primarily based on the use of Nokia-supplied DSLAM's (Digital Subscribers Line Access Multiplexers) at the local exchange, and "M10" modems at the customers' premises. Both products were designed to the then current version of the US standard, T1.413. Our aim was, and still is, to move to products complying with ITU Recommendation G.992.1. Although the ITU announced the availability of this new Recommendation in mid-1999, they subsequently struck some problems and the document is yet to be published. Failing finalisation of ITU Recommendation G.992.1, Nokia's development and Telecom's planning has had to move on since mid-1999. Nokia have now produced DSLAM's and modems to a more recent version of the T1.413 standard, using chipsets from Alcatel. Even these products may not be fully compliant with whatever the ITU finally decides, as the technology is advancing rapidly. We expect such services as multiple voice circuits within the ADSL "bearer" in the not too distant future. It has now become apparent that the earlier T1.413 product is going to be "orphaned", as it is incompatible with the version now being purchased. As a result, Telecom has to face the possibility of replacing all equipment provided to its "first generation" standards. While it was not our intention, we understood that there was a possibility of this happening, hence our decision to delay publication of interim PTC requirements. At least no other CPE suppliers are now faced with the prospect of product recovery. In parallel with product development, the various parameters of the protocol are being firmed up. Our aim is to produce specifications in sufficient detail to ensure that products from different companies will inter-operate successfully. Inter-operability testing procedures are being defined and laboratories are preparing to carry out this work. For example, Nokia, Alcatel and other manufacturers are understood to be setting up inter-operability test facilities and developing their procedures. Independent facilities, like the University of New Hampshire, have also been doing a lot of this work. Telecom is working closely with Nokia on the specification issue, but we are still not in a position to define PTC requirements with sufficient detail for other suppliers to design product with the assurance that it will inter-operate with the later Nokia DSLAM. Even more significantly, we can give no guarantees that even this new generation of DSLAM will be fully compatible with future versions. We are exploring the concept of a series of "simple practical tests" under local line conditions, connecting other parties' CPE to the latest Nokia DSLAM. This would give some indication of the level of compatibility, but the protocol is very complex. It would not only be very difficult to determine whether another product is fully-interoperable, but no assurance can be given that the present interface is completely stable and that it will not be subject to further changes. The other problem with this approach is that we are not likely to know just what is wrong if a product does not work correctly. We are continuing to look into ways in which we can open the ADSL CPE market to other suppliers and would welcome any suggestions from the industry as a whole. From Telecom's viewpoint, the quicker other suppliers can enter the market, bringing the possibility of customers purchasing new PC's "ready to run" on "Jetstream", the quicker and easier it will be to build our customer base and revenues for this service. 2. "VOICE OVER PACKET" PABX TRUNK SUPERVISION It is noted that some Voice over Packet (VoP) PABX systems are introducing a new potential "problem" with respect to trunk supervision and call charging. Because the basic call set-up and clearance arrangements are covered internally by packets sent within the system, disconnection of a terminal or loss of power to a terminal means that it cannot actually send a call release packet to its control system. As a result, a trunk can be held indefinitely. Telecom requires that answer and release signals be passed back from a PABX system to ensure that trunks and the public exchange switch is not unnecessarily held up. Also, of course, that call billing accuracy is not impaired. In the case of a VoP PABX, any situation where the terminal is disconnected or de-powered is to result in activating a time-out feature to ensure that exchange trunks are not held out of service indefinitely. A time-out period of no more than 5 minutes is required. 3. "SYNCHRONISED" CALLING We recently had a situation where part of our packet network was disrupted by a large number of CPE devices being triggered to dial the same number, time after time. This event was caused by a combination of conditions, although primarily due to some units not being able to communicate effectively with a central unit. The basic requirements for automatic calling devices are covered in PTC 200, which states that "no more than 10 call attempts are to be made to the same number within a period of 30 minutes and that the device shall delay for at least 30 seconds between the end of one attempt and the start of the next". The devices in question met these requirements. The problem arose only because there were so many of them dialling the same number. Our PTC requirements have proved suitable for the vast majority of situations in practice, which range from ordinary residential CPE, such as fax machines, to commercial devices like river level monitoring sites. The latter may be programmed to make hundreds of calls to the same number over a period of several months, and this is quite acceptable. The PTC conditions also deal reasonably well with devices like alarm systems, which obviously can't wait around for a re-dial while the associated premises are being ransacked. We do not want to set unreasonable restrictions on connecting devices to our network, but technology is developing in ways that have the potential to trigger hundreds or even thousands of CPE items to operate in unison. This could result in the sort of congestion problems caused by radio and TV stations asking their listeners or viewers to immediately dial "X" to try for a prize. It is recommended that CPE suppliers and service providers consider the potential for problems of this nature whenever there is some sort of central control system downloading software to large numbers of remote sites. A new PTC recommendation along the following lines may be worth consideration. "Where any automatic calling devices are under some form of centralised control, such that it would be possible to trigger large numbers of those devices to call the same number or numbers at about the same time, it is recommended that the user negotiates the number of re-dial attempts and the delays between attempts with the Telecom service concerned". Because the circumstances are so varied, our aim would be to assess each situation and negotiate specific calling conditions or precautions for each case. This should either avoid, or at least minimise, the risk of network disruption. 4. PREMISES WIRING: SAFETY AND RELIABILITY ISSUES The failure of jackpoints from corrosion due to dust or dirt contamination and damp continues to be a significant source of customer service problems in residential premises. There is also a need to remind installers that telecommunications wiring practices must be compliant with the Electricity Regulations and NZS 3000. Both issues are addressed in PTC 103, our Code of Practice for residential-type premises wiring. The requirements to fit flush-mounted jackpoints into "substantially enclosed flush boxes" and to always enter cables from below a flush or surface box address the reliability issue by avoiding paths for water and dust ingress. A further step to improve reliability is that unsheathed cable must be retained in the box, with all ends of sheaths and spare wires below and clear of PCB. This again, avoids risk of water being transported in or on the cable sheath onto the circuit board and components. While these requirements are largely focused around reliability, there is also a potential safety issue in relation to the segregation of 230 V services from telecommunications services. It is usual to provide at least 50 mm separation between TNV and LV wiring, but this is not always practicable when both classes of cable are in the same wall cavity and usually not firmly fixed in position. It has been accepted that where both classes of cable are fully sheathed, the risk of hazardous contacts is negligible. However, should the sheath be missing from either class of cable (or even both, in some locations close to fixed connection points like power outlets and lighting switches, or jackpoints), the risk of contact is not acceptable. Since completely open "mounting brackets" are accepted for 230 V wiring and unsheathed wires can be expected in the vicinity of any such terminations, the use of a substantially enclosed flush box for telecommunications purposes, with all unsheathed wires contained within it, is also a safety matter. As a further safety measure, we also specify that there should be either at least 200 mm horizontal separation or a rigid barrier (such as a wall stud or dwang) between jackpoints and 230 V fittings. A type of fully enclosed flush box that is recommended for telecommunications applications is the "SuperLux" metal box. There are other substantially enclosed plastic flush boxes available (although these are not necessarily stocked by all electrical wholesalers). Telecom's preferred practices are based on surface mounting all jackpoints, wherever possible. The mounting box has the added advantage that it completely encloses the jackpoint components and provides protection from moisture ingress from damp wallboard, which can be quite common in any rooms subject to condensation. Again, this is a reliability issue, and it is always worth keeping the size of cut-outs to the minimum needed to get the cables into the box. 5. NOTIFICATION OF NEW OR ADDITIONAL ESN-SERIES FOR CELLPHONES Electronic Serial Numbers are unique to each cellphone. They currently consist of a 32-bit binary value; 8 bits for the basic series and 24 bits for the serial number of the individual cellphone. The 8-bit series numbers are allocated to the original manufacturer by the Telecommunications Industry Association (originally, these were allocated by the FCC). Subject to some special exceptions, each ESN series number is allocated to an individual manufacturer. The ESN is to be incorporated into the cellphone in such a way that it can only be changed by authorised service centres. Any attempt to alter the ESN by persons without the necessary facilities are to "render the product inoperative". As a means of controlling what may be connected to the Telecom Cellular network, our Telepermit conditions require that the supplier notifies us of the ESN-series allocated to each type of mobile station intended to be connected to the network. This information is shown in the Telepermit Register and entered into both the Cellular Customer Management System (CCMS) and our Integrated Customer Management System (ICMS). Suppliers also supply the blocks of serial numbers allocated to the individual cellphones in that ESN-series. As a result, any attempt to connect a cellphone with an "unknown" ESN will be rejected. This process also provides security against theft, as a stolen cellphone can be locked off the network and it is then of no use to the person attempting to use it. Those parties supplying cellphones for the Telecom network are reminded of the need to advise either Access Standards or our Cellular Engineering Group. This applies to any cellphones imported with new or changed ESN's relative to those that have previously been notified. Further information on the TIA's ESN allocation process is available from:- http://www.tiaonline.org/standards/esn 6. USE OF TELECOM "GREEN PIPE" New Zealand's building telecommunications cabling standard, AS/NZS 3080, does not address the standardisation of colours for cable conduit within buildings. Similarly, there is no formal standard covering the colours of underground telecommunications ducting, although the New Zealand telecommunications industry has a de facto standard in Telecom using green, CLEAR using light blue and Saturn using grey. Orange for electricity and yellow for gas are also well established. The telecommunications position is, of course, complicated by the presence of older plant in grey PVC, asbestos-cement and other types of ducting. However, the overall aim is for contractors to be able to easily recognise their own plant and keep clear of other parties' plant. Telecom has recently entered into an agreement with Redeal Ltd, under which that company will handle the supply chain for a large number of Telecom "Specified Products" - those which have to be used by Telecom contractors in building and maintaining the network. As a matter of interest, these products are listed on our website as a service to these contractors, with the URL http://www.telepermit.co.nz/supply.html. Since many of these products are available for anyone to purchase, and "green pipe" is no exception, there is a potential for the above colour identification system to be breached, inadvertently or otherwise. Unfortunately, our de facto practices mean that we cannot adopt an overseas standard in its entirety. For example, Australia's AS 3084, clause 7.3.2.2.1, says conduit or pipe for Australian telecommunications use shall be WHITE, so it does not fit with any of the colours used here. Australia's TS009 contains an over-riding condition that telecommunications cabling SHALL NOT be installed in pipes of colours designated in AS 1345 for hazardous services, eg, orange for power, or yellow-ochre for gas. Needless to say, we do not want power or gas enclosed in our green pipe. Wherever they are seen by the public or building occupants, exposed pipes for telecommunications within buildings are preferably neutral colours, such as cream, light grey or white for aesthetic reasons. Conduit is especially inflexible in its application and its use should only be considered where outlet locations are permanent, there are few cables or wires, and no flexibility is required. In service areas (basements, over-ceiling cavities), it is usually better to use cable trays or catenaries and gain a lot more flexibility for additions and changes. "Telecom Green" pipe shall only be used underground for Telecom services and that any other unauthorised use of "Telecom's pipe" is at risk of being cut by our operations at any time. For in-building use, any "Telecom Green" pipe marked "Telecom", is only to be used for Telecom's services. We cannot, of course, prevent anyone from using any shades of green pipe for any purpose within a building. However, Telecom has the right to insist that it must not be marked "Telecom". If it is, then we reserve the right to cut into it at any time. 7. "BLUETOOTH" RADIO DEVICES Originally set up by a small group of major manufacturers, including Ericsson, Nokia, Intel, IBM and Toshiba, the "Bluetooth" wireless protocol has now gathered support from some 1000 other manufacturers. It was originally intended as a radio link between a handsfree cellphone and a headset, but is now being extended to many other very short range radio applications. It is typically used over a path of some 10 metres, providing a high level of security and up to around 1 Mbit/s data rates. In a relatively short time, it is expected to become a very low cost and widely used system in this country. For Telepermit, which will apply to any Bluetooth products interfacing with the Telecom network, we will apply the relevant PTC Specification covering the network interface requirements. The radio path is not usually going to be of direct concern to Telecom. However, the radio path is of particular interest to the Radio Spectrum Management group within our Ministry of Economic Development. As with other radio-based products, like cordless telephones, we will require Telepermit applicants for Bluetooth CPE to provide a copy of the Ministry's acknowledgement of their Declaration of Conformity (see below), along with the test reports for network compliance. The following information will be of assistance to any suppliers of products using Bluetooth technology, whether or not those products may be classed as "CPE". The band 2400 - 2483.5 MHz has been allocated for Wireless LAN/Bluetooth applications in the USA and Europe. This band was previously allocated for ISM (Industrial, Scientific and Medical) applications. To avoid interference with existing services, FCC requirements do not permit the use of channels 1-11 and ETS specification 300-328 does not permit the use of channels 1-13. In New Zealand, this same band is covered by the Ministry of Economic Development's specification RFS29 covering "Restricted Radiation Radio Apparatus". The above channel restrictions do not apply here. Bluetooth products, which use spread spectrum technology, must be tested in an accredited laboratory and be shown to meet the requirements of RFS29 Part 1, Schedule 1B. This specifies the power limits and out of band emissions. The Ministry does not mandate operational specifications and protocols other than those laid out in RFS29, The manufacturer defines these. The product may use any modulation system of any bandwidth within the allocated band. RFS29 is published on the Ministry's website at http:\\www.rsm.govt.nz, under the "Radio Eqpt. Specification" section. Also, the Declaration of Conformity form, along with PIB18 describing the process, is under the "EMC Information" section. Details of the General Licence are published under the "General Licence" section. The Ministry does not demand testing specifically to RFS29, but will accept tests to any standard that meets or exceeds RFS29. For example, both the US and ETSI standards mentioned above are satisfactory. Given suitable compliant test reports, a Declaration of Conformity to the requirements of RFS 29 then has to be made to: The Senior Technical Officer (Regulatory) Radio Spectrum Management Ministry of Economic Development Unit B 52 Mandeville Street PO Box 8562 Riccarton CHRISTCHURCH NEW ZEALAND The product is then covered by a general licence and may be sold in New Zealand with no further administrative action being needed. Detailed enquiries of matters not already covered on the website may be addressed to the Ministry's Brian Emmett. He may be contacted by telephone on +64 3 343 1240, by fax on +64 3 343 1219,or by email on brian.emmett@med.govt.nz 8. VACANCY FOR AN ENGINEER IN ACCESS STANDARDS We are still on the look-out for a replacement Engineer, with either an Engineering degree or NZCE, or equivalents. The main attributes for work in Access Standards are a wide general experience in telecommunications and the ability to deal with the industry in a friendly and tactful manner. Above all, there is a need for the replacement staff member to be able to investigate new product features, developments in technologies and any other matters related to the preparation and publication of our PTC Specifications. Any telecommunications engineers with the right sort of background are invited to call me on (04) 382 5345, send a fax to (04) 384 5368, or email me at doug.burrus@telecom.co.nz DOUG BURRUS Manager Access Standards