Telecommunication system

Details Telecommunication system Telecommunication system

1996-11-06

2000-10-17

Nguyen, Chau

Multiplex communications

Channel assignment techniques

Details of circuit or interface for connecting user to the...

379413, H04L 1266

Patent

active

061342416

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a telecommunication system comprising a service switching point, a telecommunication terminal unit coupled to the service switching point by a first number of bus lines, and means for phantom power supply of the telecommunication terminal unit by the first number of bus lines.
2. Description of the Related Art
In such a telecommunication system, which particularly represents an ISDN-PBX (Private Branch eXchange), there is often the need to provide, in addition to the telecommunication terminal units which are generally enhanced-feature terminal units having many performance features, for example, added-feature telephones, a possibility of exchanging information signals within the telecommunication system, which possibility is simpler compared to the use of such telecommunication terminal units. This is the case, for example, where an emergency call system for emergencies for people in need of care is necessary. In emergencies, the operation of a complex telecommunication terminal unit such as, for example, an added-feature telephone, is too unreliable. Prior-art emergency call systems do not allow communication with a telecommunication system comprising a service switching point, so that an independent installation of the systems is necessary. The technical capacity of such a telecommunication system then remains unused. In addition, the separate cabling for the telecommunication system and the emergency call system is costly.


OBJECT AND SUMMARY OF THE INVENTION

Therefore, it is an object of the invention to improve the telecommunication system of the type defined in the opening paragraph, so that the possibility of simplified telecommunication is created with minimum expenditure.
The object is achieved in that communication means for communication to a user are provided which are coupled to the telecommunication terminal unit by a second number of bus lines and in that the communication means are supplied with power by the telecommunication terminal unit via the second number of bus lines.
Since both the power supply of the telecommunication terminal unit and the power supply of the information generating means are based on the same phantom power supply, there is guaranteed that also when bus lines are mixed up during the installation of the system, no disturbances in the service switching point can be caused by a short-circuit. A telecommunication system integrating ISDN technology, thus a telecommunication system with digital switching technology, can be extended with little expenditure in the manner according to the invention. For example, additional hardware in the telecommunication terminal unit is needed only to a limited extent. The telecommunication terminal unit may then be arranged, for example, as an ISDN telephone.
The communication means transform either DC signals coming from the telecommunication terminal unit into acoustic or optical signals for the user, or entries of the user in the communication means into DC signals for the telecommunication terminal unit. In many cases, the second number of bus lines are already provided when the telecommunication system as defined in the opening paragraph is installed. In such a case, no circuitry for additional bus lines is necessary. For a re-installation of the telecommunication system, the fact that the second number of bus lines is rendered available represents little additional cost of circuitry. It is not necessary for the telecommunication terminal unit and the communication means to have separate power supplies.
In an embodiment of the invention there is provided that a DC voltage used for supplying power to the communication means is also provided for transmitting information between the communication means and the telecommunication terminal unit. The circuitry for the insertion of the communication means into the telecommunication system is restricted to a maximum level. More particularly, at least one actuation switch can be used as a communication means, w

REFERENCES:
patent: 4920556 (1990-04-01), Wong
patent: 4998274 (1991-03-01), Ephraim
patent: 5379441 (1995-01-01), Watanabe et al.
patent: 5461620 (1995-10-01), Bergler et al.

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