 e-mail: doug.burrus@telecom.co.nz TELECOM ACCESS STANDARDS NEWSLETTER NO. 105 CONTENTS STUTTER DIAL TONE PROBLEMS AND REVISED TELEPERMIT REQUIREMENTSFSK-BASED VISUAL MESSAGE WAITING INDICATION NEW "STANDARD TERMS FOR RESIDENTIAL CUSTOMERS" NETWORK CHANGES AND CPE COMPATIBILITY NETWORK SUPPORT FOR DECADIC SIGNALLING "ORPHAN CPE" TELEPERMIT OPTIONS FOR RECEIVERSHIPS, MERGERS, TAKE-OVERS, ETC RADIO FREQUENCY TESTING TEST LABORATORY ADDITIONS AND CHANGES return to index STUTTER DIAL TONE PROBLEMS AND REVISED TELEPERMIT REQUIREMENTS Further to the article on Stutter Dial Tone (SDT) detection devices in Newsletter No 103, I mentioned that the delay was typically 15 seconds, but could be 1 minute or more. A further complication is that SDT cannot be applied until some time after the recorded message has been completed. Most message durations are less than 30 seconds, but they could be longer. These factors indicate that a SDT detector (SDTD) could be too early in going off-hook even 1 minute after the called party hangs up. There are further complications with these devices; they are triggered by "off-hooks" and by incoming rings. Some incorrectly recognize "switching complete" tone (the dial tone used when lines are set up for incoming call diversion), thus giving a false message waiting indication. Also, customers with "FaxAbility" will receive a brief incoming ring, usually answered by the fax machine. These calls do not go through to Telecom's message services, so do not need to trigger the SDTD. Another complication is where a customer sets up the line for immediate diversion. In these cases, no incoming ring is received and the SDTD is not triggered. As implied by the FCC requirement for "synchronization", a much more serious problem could result from the use of more than one SDTD on the same line. One device going "off-hook" could potentially trigger the other, ending up with a continuous "tail-chasing" series of checks for stutter dial tone. This creates unnecessary loading on our exchanges and would become quite serious if a large number of customers make use of these devices. Once the new Voice Message Waiting Indication (VMWI) service is in place, FSK signals will be activated at the same time as SDT is turned on or off. FSK signals will be sent at no extra cost to all customers connected to the various types of NEAX 61E exchanges and subscribing to Call Minder or Message Manager. Unlike SDT detection, which is dependent on the CPE checking the line at some appropriate time, an FSK receiver continuously monitors the line (as for CLI). It can detect the "on" and "off" signals immediately they are sent to line, resulting in a far more accurate indication of the message waiting status. Above all, FSK devices will not have the above timing and inter-action problems of SDT detectors. In view of the relatively short time before our more certain FSK-based VMWI service is introduced, we recommend that suppliers focus their efforts on developing FSK devices. These will provide the best solution for the 70% or so of customers connected to our NEAX 61E exchanges. From the Telepermit viewpoint, we still need to set some clear conditions on any SDTD devices required for the remaining 30% of our customer base connected to earlier exchanges. These exchanges are being retired progressively over the next few years and their lines will gradually convert to FSK. In the interim, an amendment to clause 8.1.2 (2) of specification PTC 200 is required to cover SDTDs. Most of the FCC requirements quoted in Newsletter No. 103 are logical and suitable for our network. It is in everyone's interests to align with these requirements as far as possible in order to gain the benefits of a large market base. I thus propose applying a similar set of conditions for SDTD Telepermits, as outlined below. An acceptable multi-vendor method of "synchronization" has not been clearly defined by the FCC, so I propose that we rely on off-hook timings as the most appropriate means of avoiding "tail-chasing" by SDTD's of different makes connected on the same line. SDT is applied for only 2.5 seconds before being replaced by continuous dial tone. As such, SDTD devices should go off-hook for less than 2.5 seconds to avoid being confused by two different tones. Similarly, a user checking manually for SDT is likely to be off-hook for only a few seconds unless a message is indicated. If so, the user is likely to be off-hook for the time it takes to call up and receive the message. This suggests that a possible solution to "tail-chasing" is for the SDTD to be triggered by an off-hook condition only when its duration exceeds, say, 10 seconds. As such, one SDTD would be unaffected by another going off-hook on the same line. With these points in mind, the following requirements are proposed for SDTD Telepermit purposes:- An SDTD device shall turn "on" or turn "off" some form of visual indicator, according to the presence or absence of stutter dial tone. In addition, all of the following eight conditions shall be complied with. The device shall:-
In view of the progressive conversion of all exchanges to FSK, Telepermitting ONLY dual mode SDTD/FSK devices means that users will enjoy the benefits of FSK operation immediately the service is made available with no need to make any equipment changes. I understand that this is also current US market practice. Rather than further complicate SDTD requirements to cover every eventuality, SDTD's should be regarded as a "90% solution". It is better to ignore relatively minor indicator inaccuracies under extreme or low probability conditions than risk excessive calling rates and potential congestion due only to dial tone checks. Industry comment is invited on the above proposals. In the meantime, Telecom will be studying the operational issues further. There may be some changes before the conditions are finalised and formally published in our PTC and TNA specifications. FSK-BASED VISUAL MESSAGE WAITING INDICATION Although our FSK service is scheduled for delivery later this year, it is still under development and we are not yet able to fully define all CPE requirements until the new network software is tested and formally accepted. In due course, amendments will be made to TNA 102 and PTC 200 to cover this service. However, some aspects are fairly well-defined at this stage. The service will be available only from our NEAX 61E-series exchanges (those that also offer Caller Display and "FaxAbility" ringing). Our earlier NEAX 61 and few remaining electro-mechanical exchanges will not be able to offer the feature. The network-CPE interface will conform to those parts of Bellcore Specification TR-NWT-000030 relating to "On-hook Data Transmission Not Associated with Ringing". The protocol used for the VMWI message format is expected to conform to Bellcore TR-NWT-001401. As advised in Newsletter No 102, the Telecom network will not send forward an initial "wake-up" signal. Another point is that FSK receivers should not incorporate message counters. This is because an FSK signal may be repeated each time a call is completed, regardless of the number of messages waiting. As advised above, detectors may be either FSK only, or dual mode Stutter Dial Tone/FSK operating (with automatic changeover to FSK mode as soon as these signals are detected). NEW "STANDARD TERMS FOR RESIDENTIAL CUSTOMERS" CPE suppliers and maintainers may be interested to see the new "Standard Terms for Residential Customers" (the formal name for our residential customer service contract), copies of which are being distributed with customer accounts during the current billing period. The new terms clarify the position with respect to the maintenance of customer premises wiring and customer-owned CPE. In particular, reference is made to our "standard wiring maintenance service" and what it covers. Any Telepermitted Telecom-style square jackpoints with BT sockets are covered, as before, but we exclude any that are incorrectly wired and have never worked properly. Fixing such installation faults is a customer responsibility, either to take up with the original installer, or to pay another party (including Telecom) to make the necessary changes. A service now included relates to jackpoints of "different" designs that are not supplied by Telecom. While our service staff will not provide exact replacements of any special or proprietary designs, they are authorised to fit matching units supplied by the customer during the service visit. This means that if a customer choosing to use such units is advised to hold a spare on-site, our staff may be able to restore service to a faulty jackpoint, rather than simply disconnect it or replace it with a standard Telecom type. In all cases, the replacement and the original jackpoints must have BT 6-way sockets and must be Telepermitted. The new terms also make it clear that where faults are in privately-owned CPE, it is the customer's responsibility, not Telecom's, to arrange for the repairs to be carried out, usually by the supplier. A particularly significant clause in relation to the following items is under section 6, dealing with "Your responsibilities to us". As with earlier issues of the Standard Terms, the exact wording is "make sure nothing is connected to our network unless it has a Telepermit or Telecom label on it; this helps make sure the equipment does not damage our network but it does not mean that it will always remain compatible with our network". NETWORK AND FEATURE CHANGES IMPACTING IN-SERVICE CPE As explained in Newsletter No. 104, rapid advances in technology are catching up with some earlier equipment. While we have generally tried to ensure that there is "backward compatibility" between old and new services and new technologies, we are not always able to ensure that all old CPE designs will be compatible with new services or changed network interfaces. Similarly, we are not able to ensure that the whole of our network can support new services. A common example of this is the limited range of services offered by our earlier telephone exchanges. To further complicate matters, there are now over 4 300 Telepermitted items, covering a wide range of product types. As a result, it is virtually impossible to set up a system that can ensure that any combination of products will work correctly together when connected on the same line. Similarly, with the ever-widening range of network services, we cannot always ensure that one service will not clash with another. A simple example is that given above, where immediate divert could potentially fail to trigger a SDTD because the line does not ring. Most CPE products are also changing rapidly and few designs remain on the market for more than 2 or 3 years. Many devices, such as modems and fax machines have an even shorter market life. It was for this reason that we dropped the original plan to require periodic re-certification of Telepermits (ref. PTC 100, clause 7.5). Due to these rapid product changes, few, if any, of those products most affected by network and service changes are now actively marketed. The only exceptions are older products that have been reconditioned and are now being offered on the second-hand market. Our Telepermit system is based on the principle that, once Telepermitted, products may remain connected to the Telecom network. We do not and cannot undertake to ensure that products will always remain compatible with the network. The network itself does not change "instantly" nation-wide, but changes are continuous and will progressively affect more and more customers. As a result, only the user can decide when a particular product no longer meets current needs. What is becoming quite clear now is that anyone offering second-hand equipment for sale and any customers contemplating purchase of second-hand equipment to an early design should look at the Telepermit label to check the year of issue. All Telepermitted products should be labelled and all have the same label numbering format, on the lines PTC xxx/year of issue/serial number for the year concerned. For example, if a second-hand PABX system has a Telepermit number like PTC 207/89/165, the customer should be advised to carefully check its compatibility with current requirements and gain a formal assurance that there will be ongoing service support before purchasing the system. As a general rule, it is recommended that any customer should take special care to check compatibility, suitability for purpose, and ongoing servicing prospects if the Telepermit label indicates the design is much more than 5 years old. NETWORK SUPPORT FOR DECADIC SIGNALLING The next type of PSTN switch to be purchased by Telecom after our current NEAX 61E systems are no longer available and many new transmission systems are not expected to provide support for our "reverse decadic" signalling. We are the only country in the world using this system and it is not economic for suppliers to programme their equipment for such a small market. This development will impact primarily on the remaining users of decadic signalling telephones. Only one "decadic only" telephone (a replica antique telephone) and two dual mode decadic/DTMF telephones have been Telepermitted in the past 5 years, so the impact on current sales by the CPE industry is negligible. We recommend that all such dual mode CPE be switched to "DTMF" as a matter of course. As a sub-set of the ongoing compatibility issue, there have been many changes in product agencies since the Telepermit system was introduced in 1987. In some cases, take-overs and mergers have resulted in the new company taking over maintenance and support of earlier products. In other cases, the agency has simply disappeared due to a product not proving successful on the local market. We had originally planned to use the Telepermit Register as a form of reference document for product support status, but we are rarely advised of companies going out of business or products being superseded, and the level of feedback from other suppliers or retailers has been low. We hope to publish the Register on the internet some time this year and will invite "readers" to advise us of further changes. Use of the internet will make the Register a lot more accessible by retailers, customers and support companies. Hopefully, this will also improve the amount of feedback and we will be able to make it a more useful reference source. TELEPERMIT OPTIONS FOR RECEIVERSHIPS, MERGERS, TAKE-OVERS, ETC Unfortunately, the initial plans of some Telepermit holders are not successful and there may be a need to arrange transfers of Telepermits from one company to another. It must be stressed that Telepermits have a commercial value that should not be overlooked by receivers or parties considering a take-over. An important principle of our Telepermit system is that we clearly separate the ownership of test reports from the ownership of the actual Telepermit. This permits an overseas supplier to appoint more than one local agent, transfer agencies, or make any other commercial changes. In effect, the testing is the most the expensive part to repeat and we endeavour to ensure that suppliers are not put to unnecessary cost. In view of the number of questions that have come up recently, the following summarises the options that are available. Additional Telepermits An overseas supplier owning the test reports and wishing to appoint another agent, either additional to or in place of the original agent, can simply authorise the new agent to make use of the test reports in applying for a new Telepermit. This has no impact on the original Telepermit, although the original Telepermit holder may no longer be able to source the product concerned. The standard processing fee applies. A similar situation arises where the overseas supplier owning the test reports wishes to sell the same product under a different brand name. Again, the new distributor for the product is authorised to make use of the test reports to apply for a new Telepermit and the standard processing fee applies. In both cases, the new Telepermit applicant submits a letter of authorisation with the application. As long as there is a clear reference back to the original Telepermit under which we hold the test reports, we do not need additional copies of these reports. Transferring Telepermits Should the Telepermit holder own the test reports and drop the agency or go out of business, the simplest approach is for the ownership of those test reports to be transferred to the new agent. The commercial arrangements are to be agreed between the parties concerned and Telecom is not involved in these aspects. The original Telepermit holder can advise us directly that a transfer has been agreed to, or the proposed new holder can include this authorisation with the application. Since we are only involved in revising the Telepermit Register, a reduced fee is incurred. In some cases, the original Telepermit holder may refuse to make the test reports available to the new agent, even where the manufacturer has cut off supplies. In such cases, the new applicant may have to repeat the tests in order to support the application, as neither we, nor the new agent, may make unauthorised use of the original Telepermit holder's intellectual property. Receiverships These are a little different in that once the Telepermit holder has gone into receivership, we can only take instructions from the receiver. In this respect, it would be desirable that we be informed as soon as the receivers have been appointed. However, this may not always occur in good time. Contractual relationship In all cases, the new Telepermit holder is required to sign the application form, by which an undertaking is made to comply with the general conditions of PTC 100 and any special conditions of grant. When the permit concerned is owned by another independent party, it is totally unacceptable to Telecom for a new agent to simply sell a product claiming that it is Telepermitted. Telepermitted products already in service When changes of ownership of a Telepermit arise, it is expected that the new Telepermit holder will support product already sold by a predecessor. Further to the closure and possible sale of the Ministry of Commerce test facility in Auckland announced in Newsletter No 104, I am pleased to report that the facility is continuing to operate under new ownership. The laboratory is now operating as EMC Technologies (NZ) Ltd, and continuing with the same range of testing services. The contact numbers and PO Box number has not been changed from that shown in our Telepermit Overview for the Ministry of Commerce. TEST LABORATORY ADDITIONS AND CHANGES Telepermit test laboratories recently accredited by Telecom are now offering their services to prospective Telepermit applicants. Details are as follows:-
Parkside Laboratories Ltd are also accredited by the Ministry of Commerce for conductive radiation testing, susceptibility and ESD testing.
There are also some changes in the laboratory details, as published in issue 23 of the Telepermit Overview. These changes are as follows:- Intertek Testing Services have advised that their new address after 6 April 1998 will be:
Detecon Inc have advised that they have been taken over by TUV Rheinland and are now operating under the new owner's name. Revised details are as follows:-
DOUG BURRUS Manager, Access Standards |