11.1
General
(1) This Section deals with features and services not covered elsewhere in this Specification. In some cases, the features are associated with supplementary network services provided by Telecom.
(2) All features which are likely to interact with the Telecom network shall be declared either to the Testing Authority or to Access Standards during the Telepermit application process for the product concerned.
* Should service problems result in the discovery of an undisclosed feature of this nature, subsequent to the grant of a Telepermit, this may result in cancellation of the Telepermit by Access Standards. (3) If there is any doubt about the need to test any product features, it is strongly recommended that testing and compliance requirements be discussed with Access Standards prior to commencement of testing.
* In some cases, existing overseas test reports may be quite adequate. In other cases, additional tests may be required and it will assist applicants if they are aware of this before approaching a Testing Authority.
11.2
Telephony products
Some telephony product features or functions are not covered directly elsewhere in this Specification. Some of the more common examples are given below together with the action to be taken. The list is by no means exhaustive but it serves as an indication of the approach to be used:-
(a) Telephones providing hands-free dialling, monitoring, or full loudspeaking facilities, but not equipped with handsets:-
- Test results for products issued by nationally accredited overseas laboratories to appropriate national or international standards will generally be considered for Telepermit grant. In general, the performance of the device shall comply with the requirements of this Specification. Each case will be treated on its individual merits.
* There are at present no test facilities for loudspeaking functions readily available in New Zealand.
(b) Special purpose telephones used only in small quantities and not intended for sale to the general public:-
- Test results for products issued by nationally accredited overseas laboratories to appropriate standards will generally be considered for Telepermit grant. Some of the requirements of this Specification may be relaxed, at the discretion of Access Standards.
* Typical examples are lift telephones, encrypting telephones, explosion proof and intrinsically safe telephones used in the mining and petro-chemical industries, and telephones for the hard of hearing and handicapped people.
(c) Devices with headsets supplied as the normal means of communication:-
- Test results for the electro-acoustic requirements of headsets issued by nationally accredited overseas laboratories to appropriate standards will generally be considered for Telepermit grant. The performance of the
device and headset combined shall comply with the requirements of this Specification.
(d) Devices where headsets are offered as optional attachments to replace or supplement the telephone handset normally provided:-
- A Telepermit is generally granted for the handset option alone and the device and handset combined shall comply with the requirements of this Specification. A separate Telepermit is then granted for each headset design offered and the normal requirement is as stated in (c) above.
* There are at present no test facilities for headsets readily available in New Zealand.
* Replacement headsets for use on PABX's, etc, will be treated as in (c) above, except that test results will be accepted from manufacturers.
* Telepermit category PTC 208 has been allocated for headsets and/or handsets when supplied as separate items.
(e) Conference terminals (excluding conference bridging equipment):
- Test results for products issued by locally accredited overseas laboratories
to appropriate standards will generally be considered for Telepermit grant.
The performance of the device shall comply with the requirements of this Specification. If necessary, consideration will be given for a Limited Permit trial along the lines of that described in Specification PTC 207 for PABX's.
* There are at present no test facilities for conference terminals readily available in New Zealand.
(f) Devices requiring other special testing arrangements:
- Special test requirements can usually be arranged with Testing Authorities following discussions with Access Standards.
11.3
Distinctive Alert decoders
11.3.1
General considerations
(a) Type 1 decoders shall satisfy all the requirements of the devices with which they are integral.
(b) Type 2 decoders shall satisfy all the requirements for series connected devices.
(c) Type 1 decoders with a separate terminal port for connection of another device shall satisfy the requirements for both Type 1 and Type 2.
(1) Distinctive Alert decoders (see also Section 7) shall satisfy all relevant requirements stated in this Specification as follows:-
Return to Contents
11.3.2
Type 1 decoders
The requirements for a Type 1 decoder designed as an integral part of another device (e.g. a fax machine) are largely covered elsewhere in this Specification. The following
additional requirements apply:-
(a) Decoders integrated with automatic answering devices should decode the ringing cadence as quickly as possible, and preferably answer after the first complete cadence.
* This will avoid unnecessarily ringing telephones that are connected to the same line.
(b) Unless a dispensation has been granted by Access Standards, no CPE shall answer in less than 3 seconds(ref. clause 8.2).
* This ensures that a caller hears at least a short burst of ringing tone indicating successful connection.
* Another significant reason for this applies to customers with analogue caller line identification. Answering within 3 seconds will destroy any analogue data which may be transmitted in the period between the end of the last ringing burst within the first cadence, and the end of that cadence.
(c) Where decoders are integrated with fax machines, consideration should be given to providing the customer-controlled option of disabling "Call Waiting". This prevents the call waiting tones of an incoming call from corrupting a fax transmission already in progress.
* Disabling "Call Waiting" for the duration of a call can be achieved by prefixing the dialled number with '*52'.
* It must be noted that '*52' must NOT prefix a call if "Call Waiting" is not subscribed to by the customer. Therefore, if insertion of the prefix is automatic, it is essential that it can disabled by the customer.
* On all incoming calls to the number corresponding to the ringing cadence DA4, "Call Waiting" is automatically disabled at the exchange for the duration of the call.
11.3.3
Type 2 decoders
(1) A block diagram of a typical Type 2 decoder is shown in Fig 11-1. While this is not the only way of implementing the Type 2 decoding function, it shows the aspects necessary to satisfy requirements
(2) Analogue Calling Line Identification (CLI), which is an on-hook data transmission facility described in Document TNA 102, Sections 10 and 11, shall be taken into consideration when designing Type 2 decoders.
(3) To ensure that users are advised of the level of compatibility with Analogue CLI, an appropriate note shall be inserted in the User Manual (see examples in (4) below).
(4) One of the following typical methods of applying blocking conditions may be used. These examples are typical, but other methods may be used and any proposal will be considered on it's individual merits:-
(a) The decoder blocks on-hook data transmission.
User Manual Note example:-
"Any equipment designed to receive Caller Display information must be connected on the network side of this equipment."
(b) The decoder includes an on-hook data receiver or Caller Display function, but blocks the transmission of such data to its output ports.
User Manual Note example:-
"This equipment is designed to receive and decode Caller Display information. Any additional equipment designed to receive on-hook data transmissions must be connected to the network side of this equipment."
FIG. 11-1 TYPICAL TYPE 2 DISTINCTIVE ALERT DECODER BLOCK SCHEMATIC
(c) The decoder regenerates the on-hook data transmission as well as the ringing signal, and inserts the data in the appropriate part of the regenerated cadence as stated in Specification TNA 102, Sections 10 and 11.
User Manual Note example:-
"Equipment designed to receive and decode Caller Display information must either be connected to ports 1 and 'x' etc., or be connected to the network side of this equipment."
(d) The decoder is transparent to one (or more) ports for the first cadence and switches to the appropriate port after the first cadence has been decoded (but not before the completion of the long silent period during which on-hook data would be transmitted).
* It is acceptable for the decoder to be transparent to d.c. and voice frequencies, but to block ringing if desired.
User Manual Note example:-
"Equipment designed to receive and decode Caller Display information must either be connected to ports 1 and 'x' etc., or be connected to the network side of this equipment."
11.3.4
(a) For the duration of a call in progress to or from another connected terminal
device.
(b) For up to 3000 ms following the commencement of any incoming ring.
Access to the network via Type 2 decoders
(1) A Type 2 distinctive alert decoder shall not restrict its terminating devices from initiating outgoing calls and receiving incoming calls (subject to any ringing decoding process), except under the following circumstances:-
* This is to provide an adequate window of time embracing one complete cycle of ringing cadence to enable a ringing decoder to correctly decode one cadence.
(c) For 100 ms following application of the on-hook condition to the PSTN line
indicating completion of a call to or from any connected terminal device.
(d) For up to 3500 ms from cessation of incoming ringing where the caller
terminates the call before it is answered.
* This is to provide an adequate window of time for the decoder to detect lack of incoming ringing and revert all ports to idle.
(2) Emergency access to the Network (e.g. for '111' calls)
When the line port is switched through to one of the terminal ports (e.g. for a fax transmission), there are a number of options open for allowing other ports emergency access to the network. It will be necessary to release any existing call before access can be gained. The options are:-
(a) When any device connected to a port goes off-hook it will normally be expected that busy tone will be received from the decoder (this is not mandatory however). The device then sends forward a signal e.g. SHF or a DTMF tone, which signals the decoder to drop the existing call and connect the network to that port.
* This option has the advantage that it prevents the accidental crashing of other calls. It is however more expensive to implement, especially if a DTMF receiver is required.
* A DTMF "1" would have the advantage of being the same as the common PABX access digit.
(b) If there is no provision for accessing the line while another call is in
progress, then the User Manual shall clearly state this fact, and give instructions to the effect:-
"to make emergency calls, any other calls in progress must first
be released."
* Note that if several single output decoders are connected in parallel, any one decoder is unlikely to be able to clear down calls which are passing through other decoders. The above warning will generally be required in this situation.
* Care must be taken to make sure no lockup situations arise from solutions to emergency access.
11.4
Analogue Calling Line Identification (CLI) equipment
11.4.1
General
(1) Analogue CLI equipment designed for the Telecom 'Caller Display' service uses the on-hook data transmission facilities described in Technical Document TNA 102, Sections 10 and 11.
(2) The basic on-hook requirements stated in this Specification apply to analogue CLI equipment except where specificaly stated in the following clauses. Also, there are certain requirements and design considerations which are not covered elsewhere in this Specification. The following clauses detail these additional requirements, and also include some general requirements for on hook data transmission devices which could be used for future services. Fig. 11-2 shows the test set up for these additional requirements for analogue CLI devices.
(3) Where the CLI receiver is incorporated in other customer equipment covered by this Specification, then the normal overall requirements for that type of equipment will apply, along with the following additional requirements.
(4) Analogue CLI equipment which is compatible with the recommendations of Bellcore Special Report SR-TSV-002476, Issue 1: December 1992, is likely to satisfy the requirements of this Specification. There are some differences which should be noted and these are stated where appropriate.
* The Telecom on hook data transmission and associated analogue CLI requirements are based on the Bellcore system. However, to call back the number passed forward from the network, digit insertion or deletion is necessary. This impacts on the design of any devices which provide a dial-back feature.
Notes:
Checksum = 2's complement of the modulo 256 sum of all words from the message type onwards
Modulo 256 sum = exclusive OR of each word
2's complement (X) = $00 - X
FIG. 11-2 TEST SET UP FOR ANALOGUE CALLING LINE IDENTIFICATION EQUIPMENT
11.4.2
(a) This impedance shall be removed either when the second ring cadence occurs (preferably just before), or when another device on the same line goes
off-hook.
(b) If coded ringing is implemented on the same line, the unit shall also decode the ringing to determine when the impedance should be applied and removed.
On-hook impedance
(1) During the reception of data the receiver of an on-hook device may, for the purpose of improving impedance matching, terminate the line with a more suitable a.c. impedance (e.g. BT3) than that stated in clause 4.5.2. In this case the following shall apply:-
* There is potential for confusion between DA2 and DA4 because of the extended silent period between the first two bursts of ringing.
* The difference should be noted between the standard Telecom New Zealand off-hook impedance BT3 (ref clause 4.5.1) and the 600 ohm plus 2.16 µF series network commonly used on North American products. However, it is not anticipated that this difference will cause any problems for on-hook data transmission.
(2) At all other times, the on-hook impedance shall be as stated in clause 4.5.2.
11.4.3
Ringing
(1) The four ringing cadences (DA1 - DA4) used on PSTN lines are described in Section 6 of Technical Document TNA 102, and the requirements for response to these cadences are detailed in Section 7 of this Specification. On hook data, when available, will be capable of being transmitted on all four cadences.
(2) It should be noted that, due to the difference in cadences, there is less time available for data transmission than the nominal 4 seconds available in North America. This limits the amount of data that can be sent, particularly for cadences DA3 and DA4, but this should not impact on the receiver.
* Although not planned at present, there is always the possibility that Telecom may, at some future date, increase the data capacity by shortening the 500 ms and 200 ms gaps before and after data is transmitted (see Fig. 11-3), and also the message preamble (250 ms CSS and 180 ms mark). Any equipment not dependent on the timing of these signals would remain compatible should such changes be implemented.
(3) On hook data transmission receivers shall be compatible with the requirements of Section 7 of this Specification.
(4) It is strongly recommended that on hook data transmission equipment should always look for data, and not use ringing as a 'wake up' signal.
* This will allow the device to be comaptible with future services such as 'message waiting indication' which use on-hook data transmission not associated with ringing.
* Any device which looks for data at all times and does not terminate the line should not experience any difficulties with the Telecom New Zealand ringing cadences DA1 - DA4.
* Any device which uses ringing as a wake up signal for data reception or to switch in an a.c. terminating impedance during data transmission is likely to experience difficulties with the ringing cadences, particularly DA4.
11.4.4
(2) Receivers should be capable of receiving data during any of the four ringing cadences used (see clause 11.4.3(a) above). If not, a suitable warning shall be included which clearly explains to the customer which DA codes the device is compatible with. Fig. 11-3 illustrates the timing requirements for analogue CLI devices with respect to the different DA codes.
Data capture
(1) The receivers of all devices which use on hook data transmission shall be capable of receiving data in the format described in Technical Document TNA 102, Section 10. Both single data message format (SDMF) and multiple data message format (MDMF) shall be supported.
* It should be noted that the data is limited to 'Time/Date' and 'Directory Number' when sent with DA3 and DA4 cadences.
(3) Receivers shall perform satisfactorily when connected via a zero, 3 km and 6 km artificial line (see Fig. 4-1(b) in Section 4). In each case the test shall be carried out with and without a ringer built out to a RN of 5 (ref. Section 7) connected in parallel. The ringer shall remain operational for all the tests in which it is connected.
(4) All messages that contain corrupted data, as indicated by an incorrect checksum, shall be discarded.
(5) It is recommended that the receiver functions should be independent of the exact length of the CSS and pre-message mark signal.
* These are not included in the checksum and do not carry any information except to function as a 'wake up' signal.
| *1 10 bits per character, 1200 bps | *3 Overhead for MDMF | ||
| Message Type | - 1 Character | ||
| Message Length | - 1 Character | ||
| *2 Overhead for SDMF: | Date/Time Parameter Type | - 1 Character | |
| Message Type | - 1 Character | Date/ Time Parameter Length | - 1 Character |
| Message length | - 1 Character | Date/Time | - 8 Characters |
| Date/Time | - 8 Characters | Directory Number Parameter Type | - 1 Character |
| Directory Number | - X Characters | Directory Number Parameter Length | - 1 Character |
| Checksum | - 1 Character | Directory Number | - X Characters |
| Name Parameter Type | - 1 Character | ||
| Total Characters = | 11 + X | Name Parameter Length | - 1 Character |
| Name | - Y Characters | ||
| Checksum | - 1 Character | ||
| Total Characters = 17 + X + Y | |||
11.4.5
Number format passed from the network
(1) For local and national calls, the number sent forward from the Telecom network is in the format "area code" plus "customer number". No "0" national call prefix is passed forward from the network.
* This is the format used within the Telecom network and between New Zealand networks for passing calling numbers. For such applications, the "0" has no meaning.
* Display equipment designers should note that there is no format differentiation between national and local calls.
* The great majority of calls will consist of 8 digits, but a few calls from the Telecom cellular network will be of 9 digits in total.
* As examples; on a typical 10-digit display originally designed for the North American network, an Auckland caller's number could be displayed as "9 876 5432". Telecom cellular callers' numbers, which could be either 8 or 9 digits, could be displayed as "2 567 8901" or "25 234 5678".
(2) For incoming international calls entering New Zealand via a Telecom International Exchange, the digits "0000" are currently passed forward. This will continue to be the practice for any international numbers that are either not available or need to be withheld in the future for any reason.
* The actual numbers are currently withheld to protect the privacy of overseas callers.
* It should be noted that not all international calls arrive in New Zealand via the Telecom Gateway. Many arrive via other carriers.
(3) In due course, some international numbers are expected to be made available to New Zealand customers. Where such numbers are available for presentation, the number sent forward from the Telecom network will be in the format "country code" plus "area code" plus "customer number". No "00" international call prefix will be passed forward from the network. As a result, there could be confusion between national and international numbers on display units.
* When international numbers are available for presentation to New Zealand customers, the number length may be any length up to 15 digits. See warning note on clause 11.4.6.
* The timing for such a service introduction is unknown at this stage.
(4) For incoming calls wholly within a Centrex group, the number passed forward will be the extension number used within that Centrex customer's network. The number length will be within the range of 2 to 7 digits.
(5) The number actually passed from the network may not relate to a specific person or line.
* For example, where the pilot number of a DDI PABX group is passed forward, a display user dialling that number is likely to reach the PABX operator, not the person who originally made the call. Similarly, a small percentage of displayed numbers may not correspond with a number that can be called back.
11.4.6
Data display
(1) It is strongly recommended that the number displayed should in ALL cases correspond with the number to be dialled back by a residential or direct line user. To achieve this, the digit insertion rules of clause 5.6.2 apply.
(2) Where the display does not correspond exactly with the number to be called back, the need to insert prefix(es) for manual dialling shall be explained in the user instructions (see clause 5.6.5)
* Displaying the number complete with any necessary prefixes is most likely to avoid users calling the wrong numbers.
* Some display units will be capable of storing any digits which exceed the display length and/or any prefix digits that are automatically inserted for dialling back to the calling number. Nevertheless, it is preferred that the display matches the actual number to be dialled in all cases. This will minimise any potential confusion for users.
* Business customers connected to Centrex or PABX extensions will also need to dial a trunk access prefix. The capability to insert this prefix is regarded as a marketing feature.
(3) Where "0000" is displayed for incoming international calls and not translated into some form of informative text, the significance of the "0000" should be explained to the user.
(4) The provision of a display facility on analogue CLI devices is not mandatory as it may be provided separately on other associated equipment such as PC's. In such cases an interface such as V.24/RS232 will be necessary. Wherever provided, the following display functions are recommended:-
(a) Minimum display of time/date and the directory number.
(b) Minimum number capacity of 15 digits, which allows for full international numbers to be displayed, without prefix. For the display to include the '00' international prefix, then 17 digits is recommended.
(c) If fewer than the recommended number digits are displayed, the display should 'right justify' the full number so that the full local number will always be displayed. In such cases, it is preferable that the display has a scroll capability so that all digits can be viewed.
* Confusion can arise where displays do not show all digits of a number. For example, a 10 digit display might show "12 2283 6789" which could be a number in Sydney, Australia, with the first digit "6" of the country code not displayed. Alternatively it could be a number in Cardiff, Wales with the country code "44" not displayed, or a number in some other country for which one or more leading digits are not displayed.
* Early implementations of the Caller Display service will be restricted to sending New Zealand numbers only, but 9 digits is the maximum required at present ("25" + 7 digits for a Telecom Cellular number). However, it is expected that at some future date, the service will be extended and full international numbers will be required.
(d) Minimum capacity for name information, 20 characters.
* Name information will not be available on early implementations of the Caller Display service, and may not be present at all in some circumstances.
* Note that this field is simply alpha-numeric text and could be used for displaying more general messages.
(e) Cause of absence of display, i.e. Out of Area (O), or Anonymous (P). It is recommended that the complete IA5 (ASCII) character set for this field is decoded.
11.4.7
Data storage
(1) For on hook data transmission equipment, there are no mandatory requirements for the amount of incoming data that can be stored. However, there are obvious benefits in storing such data, particularly in unattended situations.
(2) On analogue CLI devices, it is recommended that the details for at least 10 calls be held in memory on a 'first in - first out' basis.
(3) If data storage is incorporated, the CLI device shall also discard any data which becomes corrupted.
11.4.8
Dial back considerations
(1) Requirements for automatic dial back facilities are covered in clause 5.6.
(2) Display units having no dial back facility are acceptable for Telepermit purposes. All such devices shall be provided with clear instructions to users to ensure that the risk of wrong numbers is minimised. This particularly applies to display units which do not display precisely the digits to be dialled ( clause 11.4.6).
Notes: