Cibertec.com

Dialed Digits Storage Register Interface Unit RDTMF

Technical Description

Cibertec's Interface Unit for the dialed digits storage register (RDTMF-II) is an intelligent, electronic, modular equipment that is directly installed over the dialed digits storage register in the Analogue Telephone Central Offices.

The RDTMF-II is a pulse and tone receptor. It is an autonomous and independent unit which permits to the dialed digits storage register; PENTACONTA (SESA), ERICSSON, NEC, SIEMENS, among others electromechanical central offices, to accept pulses or tones (DTMF) from the dialing subscriber.

The storage capacity of digits is increased to 24, thus allowing the telephonic administrations to fulfill the ITU-T E.164 recommendation that all switchboards and networks should have the capacity to handle telephonic international numbers with a minimum length.

Cibertec's new RDTMF-II board, in addition to the previous one, incorporates analysis of existing regional codes, avoiding route congestion when non-existing codes are dialed. The card system orders a busy tone to be sent to the subscriber or transfers the call to a recorded message.

When updating in EPROM, the RDTMF-II arranges an input command in order to commute simultaneously, all the registers data base of all the exchanges with the new codes.

Universal Operation

The RDTMF-II is universal and functions appropriately in whatever type of Electromechanic Telephone Switch, installed in the circuits of the dialed digits storage register.

Its proper functioning has been tested in the following switches:

Ericsson - ARF, Nec - NC, Siemens - ESK, CP and CPR, Pentaconta, Standard Electric - PC 32 PC 1000, Hitachi - C

Progressive Validation of Dialed Prefix

Progressive validation consists in validating the digits in agreement with the order they are received.

With this type of process, the following advantages will be achieved:

- The filtering of mistaken prefix calls from the same moment that the first invalid digit was dialed.

Besides being efficient, this process simplifies the validation logic which allows the minimization of the space occupied by the Valid Prefix Table. The equipment analyzes the first three digits in order to operate according to the case:

• I.- Blocking signal output: This obligates the forced disconnection (freeing the register and sending the busy tone backwards, to the subscriber):
  • a)Nonexistent prefix (block)
• II.- Activate the GO AHEAD signal so that the register, without further delay, proceeds to send the dialing without waiting for the time-out. The action is given, according to the case, analyzing the first three digits, to know:
  • b) Three digit number (example 911, or other special ones)
  • c) Seven digit number (example 220-7465)
  • d) Nine digit number (example 05-xxxxxxx)
  • e) Open numeration (example 0-800xx..., 00-xx...,09-xx...,etc.)
  • f) Ten digit number (example 800-xxxxxxx).

The RDTMF-II is a modern and compactly designed equipment that uses the latest generation components. Its reduced dimensions and low height allows installation in a reduced space without making alternations in the fixation, inside of the same register of any electromechanical Switch.

The control logic and the timing of the RDTMF-II is carried out by way of a stored program in a microprocessor, which is the most simple, flexible and reliable way to carry out these functions. The program includes autodiagnostic and failure indication.

Its concept is completely electronic and it does not use voluminous potential transistors, thus resulting in a low consumption and power dissipation system board.

The RDTMF-II automatically detects in which type of Switch it has been installed in order to activates the corresponding software.

The RDTMF-II supervises the time that the register remains without being taken (programmable every 24 hours). A reset by the hardware is done at the beginning of every seizure, guaranteeing a safe and reliable operation.

Automatic Blocking of Failed Registers

1.- Register supervision where the card is installed:

Thanks to the Automatic Blocking of Failed Registers, if a register is found to be defective, it will be automatically blocked by the RDTMF-II with the opening of the loop of availability. Also, the luminous alarm indicator will appear due to register failure.

To determine if an immediate block is necessary, a counter begins when the register remains permanently seized or never seized, so that if the programmed interval, i.e. (24 hours) overflows, the card will proceed with the indicated action.

2.- Supervision of its own operation:

The equipment also incorporates a software operated watch dog circuitry that turns on a red led indicator and frees the output signals buffer. There is also an operated relay that breaks the availability loop when the internal power fails. This guarantees the proper function of the program, memory and microprocessor.