7. RINGING CODE DISCRIMINATION
With the introduction of "FaxAbility" and our prospective four separate Distinctive Alerts, it was originally intended that we would mark the relevant codes on the Telepermit label of each product with ringing code selection capability. It is now clear that this is not going to be practicable.
Even for fax machines with "FaxAbility", which seemed a relatively simple case, the machine will not always be set to detect DA-4. Also, when a machine is not set to DA-4, it may or may not respond to all the other codes. In fact, some equipment may be so adjustable that it is able to either respond or not respond to all or any of the four cadences. With such flexibility, it is not possible to fit all the details onto the Telepermit label.
We are concerned that neither customers nor retailers may fully understand the setting arrangements for a particular item of equipment. If it does not appear to work properly, the customer will no doubt call on Telecom or the retailer to help sort things out. This may occur even when the reported "fault" is simply due to an incorrect setting or misunderstood functionality. Telecom can accept no responsibility for the correct operation of privately-owned and supplied CPE, but customers tend to call our faults service staff about any problems. To add to the complications, the customer may have mislaid any User Instructions and the person called may not be familiar with the characteristics of the equipment's cadence detection.
Obviously, we do not want Telecom staff called out to the customer's premises when there is little we can do to fix some basic incompatibility, other than disconnect one or other of the CPE items concerned. As with "Caller Display" devices (see Newsletter No. 86), we would like to have the ability to sort out the majority of service problems remotely. This means that service staff would need access to some sort of summary of the capabilities of any CPE which has the ability to control its answering or switching according to the ringing cadence used. As most readers will know, Access Standards does not disclose information submitted with Telepermit applications. To even consider setting up a widely accessible database on cadenced ringing capabilities, we would need the agreement of the Telepermit holder to disclose the relevant data for each product concerned.
PTC 200 requires that cadences be tested with both ± 10%, ± 20% and ± 30% tolerances on the specified standard cadences. Although ± 10% is acceptable for Telepermit purposes, it will be useful to know what products accept even wider tolerances, as these may be suitable for marginal cases where we are not currently offering the FaxAbility service. However, this further complicates any data base or presentation.
What we now suggest for these products is a "table" showing whether codes are accepted or rejected for each available cadence setting and what tolerances of the 400 ms "ON" period can be achieved. Preferably, the format of this matrix can be "standardised" for inclusion in all User Manuals. Needless to say, it would be even more accessible if suppliers are willing to label the product concerned with such a table. This will not always be practicable, so we are wondering whether the same information could be included in a Telecom database. This could help our staff to assist the customer in those cases where the user manual has been mislaid.
Two examples of a suggested standard information format are shown below. In the examples, the "Cadence Setting" shows the code that the equipment is actually set to. The response to that ringing cadence setting is then shown in the associated row of the table for each cadence, along with the acceptable tolerances. Where the equipment answers all rings unless it is set to a specific cadence, "ANY" should be used in preference to "DA-1" . All cadences are shown to avoid any doubt.
Typical fax machine with "FaxAbility", which can be set to either DA-4 or "any other cadence"
