TELECOM ACCESS STANDARDS NEWSLETTER NO. 142 September 2003 CONTENTS 1. CPE INTERFACE CHANGES RESULTING FROM NEW NETWORK EQUIPMENT 2. RESIDENTIAL AND SMALL BUSINESS PREMISES CABLING 3. USING EXISTING HOME WIRING FOR NEXT GENERATION SERVICES RETURN TO MAIN INDEX 1. CPE INTERFACE CHANGES RESULTING FROM NEW NETWORK EQUIPMENT Telecom's latest generation of access transmission systems are some the first items that form parts of the "Next Generation Network" for voice services. Telecom and its suppliers are finalising the detailed designs such that these systems will interface with our existing NEAX exchanges and provide, as far as possible, exactly the same network interface as our existing one. This way, any potential CPE compatibility problems will be minimised. Nevertheless, some minor changes will occur with the following services, as explained below. CPE suppliers are asked to check with their manufacturers if they are not sure whether their products could be adversely affected by the following changes. If any problems are found, please advise me promptly of the product's Telepermit number and the nature of the problem. A. Caller Display timing TNA 102, clause 10.2 and PTC 200, clause 11.4.4 show a 500 ms silent period immediately after the completion of the initial ringing cadence. This is followed by 250 ms of Channel Seize Signal (CSS), 150 ms of Mark signal (Mk) and the actual Caller Display information. With the new equipment coming into service, the initial 500 ms silent period following the first ring will be reduced to as little as 60 ms. The following signals will remain unchanged. This change will take place progressively as customers move into new service areas or as existing customers are transferred from cable to a new access system. This process will take place progressively and our aim is that customers will not even notice any change. However, the above clauses of TNA 102 and PTC 200 are to be amended and all new equipment incorporating Caller Display functionality is to be tested with the silent period reduced to 60 ms. This change should be applied by all test laboratories without undue delay. In case other forms of analogue on-hook data transmission were to be introduced later, PTC 200, clause 11.4.3(4) states: "It is strongly recommended that on-hook data transmission equipment should always look for data, and not use ringing as a 'wake up' signal". Subsequently, Visual Message Waiting Indication (VMWI) was introduced as a similar FSK service that does not accompany ringing. In view of the change now announced, this may now prove to be a valuable recommendation. Our testing of sample consumer type Caller Display units currently available to us showed that they all react correctly to the network signals with the silent period reduced to 60 ms. In fact, some adjunct receivers Telecom tested when the Caller Display service was first launched responded even without pre-ringing. However, many other adjunct Caller Display devices, phones and faxes with integrated CLI receivers have since been introduced. From PTC 200 testing, we know these all work with a 500 ms silent period, but we do not have samples of all of these products for testing with the silent period reduced to 60 ms. PABX/CENTREX CLI applications Unlike consumer CPE, call centres and large PABX's generally use digital trunks with calling number identification. However, CENTREX based systems and some PABX systems do use the analogue Caller Display service. We have not been able to test many of these and there is a possibility that where analogue Caller Display is used for such services as receptionist screen pop-up, logging incoming calls, etc, there could be added timing delays (within the customer's systems) which need to make use of the 500 ms silent period . In view of our testing constraints, it is recommended that suppliers of these display units and any other types of CPE incorporating Caller Display detection check to ensure that the reduced silent period will not result in malfunctioning. B. Visual Message Waiting Indication (VMWI) line reversals Introduction of the new access network equipment involves a change in the Digital Trunk Interface (DTLM) of our NEAX switches to ensure compatibility with VMWI operation. This interface is widely used to connect PABX systems and access systems using digital trunks. The actual change is a line reversal, followed up to 800 ms later by the VMWI signal. This reversal is removed at the end of the VMWI signal. This change will apply to all DTLM lines within a local exchange switch that have VMWI enabled, whether or not those lines are connected via a new access system. It is estimated that only about 40 000 lines will be affected nationwide. Nevertheless, it should be assumed that this change might be implemented on any Telecom line with Visual Message Waiting Indication (VMWI). On such lines, any remaining older telephones with bells are likely to "ding", first as the reversal is applied and again as it is removed. This is not a fault, but may cause some customers a little concern. Some types of customer equipment, (mostly analogue PABX systems, which do not commonly use the VMWI service), use the reversal as a form of fast guard to prevent the line also being seized at the customer's end. Normally, this reversal is followed by ringing, but this will not be the case with VMWI. The overall sequence is similar to a brief line seize and release, such as when callers realise they have dialled the wrong number. As a result, this short-term reversal is not expected to cause any problems for in-service CPE. However, we do not know for sure and we are not able to test all the many types of systems now connected to the Telecom network. In the circumstances, it is recommended that CPE suppliers confirm with their manufacturers that this change will not cause any mal-functioning. C. Line current reduction Most customers transferred from direct copper lines to access systems over the past several years have experienced a reduction in line current. Low feed current is a common characteristic of modern access systems worldwide and Telecom's new access system is designed to supply 24 mA, more or less independent of line length. This is well above the current needed for all types of Telepermitted CPE and not something new, as low current feed access systems have been used for many years. However, it is mentioned in case any customers report that they notice a change when transferring a call from one telephone to another on the same line. D. Further changes Work on the design of new network systems is still in progress and, should there be further changes impacting on CPE, information will be published in these Newsletters. 2. RESIDENTIAL AND SMALL BUSINESS PREMISES CABLING Further to the article on "Residential-type premises wiring developments" in Newsletter No. 140, a Telepermit has been granted for the first of the "Star Boxes" offered under the requirements of the recently revised PTC 225, which now covers star boxes (with jumpering or "hard-wired" cross-connections), as well as SOHO (with plug and socket cross-patching facilities) and various "hybrids" of these two systems. Telecom is now promoting star wiring and 4-pair Cat 5 cable for new homes, but this will require suitable cable termination hardware to be made available on the local market. Several types of Telepermitted SOHO cabinet have been installed since 1998, but suppliers of similar cabling hardware are reminded that any product offered for connection to the Telecom network in residential premises must hold a Telepermit. PTC 225 outlines a number of issues related to residential and small business cabling, especially matters relating to reliability and ongoing servicing, which will often be carried out by the end user. A key requirement from Telecom's viewpoint is that no one is confused about who will be responsible for dealing with wiring faults or corroded RJ 45 jackpoints. PTC 225 sets some relatively simple requirements for component and system suppliers. In essence, any hardware must be purpose-designed for telecommunications and, preferably, be certified for at least category 5 operation. In particular, the supplier must clearly advise customers that any such hardware is NOT covered by Telecom's residential wiring maintenance service. The "Draft for Industry Comment" of PTC 225 is now available free of charge from our website. The URL is www.telepermit.co.nz/ptc225 PTC 103 is also being revised to cover the new recommendations and place more emphasis on star wiring, although this has been one of the accepted options for some years. The revised version will soon be published on our website to provide an opportunity for industry comment. 3. USING EXISTING HOME WIRING FOR NEXT GENERATION SERVICES Newsletter No. 141 outlined recommendations for wiring new homes for telecommunications. This led to the almost inevitable question "how will existing home wiring support these new services?" Needless to say, this is a worldwide issue, as every network operator has to deal with home wiring that can be anything from new to 50 or more years old and offer widely different performance over a range of different configurations. The only certainty is that there is no one "standard" for such legacy wiring. With the new technologies now available, there are many proposed solutions to this problem under development and quite a lot of indecision in the industry as to which ones will prevail. The current most likely approach for "Next Generation Network" services is that used for ADSL when a network splitter is fitted. A new cable and jackpoint are added for the ADSL modem and the high frequency data services are completely separated from the voiceband "POTS" services, which are carried over the legacy wiring. A similar process can be used for these future services. For home LAN applications, a common theme overseas is adding "electronic boxes" to make better use of the existing wiring. These may derive a high frequency path over the existing wiring, couple the line and phone wiring to the existing power wiring (usually there are a lot more power points than telephone jackpoints in a home) or couple the line to some form of radio path. The added system is operated at MHz frequencies in order to carry high bit rate signals. The main contenders at present seem to be:- (a) Radio-based solutions, such as "WiFi" (IEEE 802.11 in its various versions: 802.11b offering up to 11 Mbit/s at 2.4 GHz; 802.11g offering up to 54 Mbit/s at 2.4 GHz and compatible with 802.11b; 802.11a offering 54 Mbit/s at 5 GHz and 802.11 e (coming). These interfaces are already being equipped on many new lap-top PC's and the first public "hot spot" public access points are now coming into service. As such, prices are falling and it is one of the stronger contenders today. Unfortunately, a lot of products, including Bluetooth for limited range devices, are already using the 2.4 GHz band which is covered by a general user licence regime and also provides for microwave ovens, garage door openers and a host of other short range radio products. (b) Home Phone Network Alliance (HPNA), which comes in three versions: V.1 at 1 Mbit/s, which did not get much support and is now superseded; V.2 at "up to 32 Mbit/s", which has now been adopted by ITU as Rec. G.989. V.2 uses frequencies above the ADSL band, nominally 4 - 10 MHz. ; and V.3, which has just been agreed, offering up to 132 Mbit/s. The "Home Phone Network Alliance" (HPNA) is a multi-company grouping developing systems that operate over the existing phone wiring. HPNA V.2 or V.3 might offer a solution for the existing home in the near future. How well these systems would go on some of our premises wiring is not known. (c) "HomePlug", which uses the power wiring for up to 1.5 Mbit/s. Although the various industry groupings are promoting their respective "solutions" (including several not mentioned above), it is very much a case of waiting to see which ones finally dominate. These are likely to be the mass-produced and so lowest cost options best suited for our needs. Some commentators are suggesting that an appropriate mix of these solutions is probably the optimum for the customer wants more than a couple of devices connected together. All of these electronic "boxes" are currently a lot more expensive than a length of cable, of course, but they may prove to be a lower cost option, for the "average" customer's existing home, than running new cable - once standards have settled and prices have reduced. Nevertheless, adding an "electronic box" between the network and the CPE for the service concerned, has potential for intermittent interference, possible service degradation or even failure. In comparison, a length of cable offers good bandwidth, it is far more secure, cheaper and more reliable. With the recent standardisation of "Power over Ethernet" (IEEE 802.3af), cable also offers power feed capability - not so easily achieved by radio devices. Meantime, for new home builders who can easily install cable before the framing is lined, putting in plenty of star-wired Cat 5 cable still seems not only the best option, but also the cheapest. DOUG BURRUS Manager Access Standards