Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1997-03-18
2001-04-17
Trost, William G. (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S552100
Reexamination Certificate
active
06219545
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a telecommunications system comprising at least one cordless access subsystem, a cordless terminal, and a network of at least one automatic branch exchange, the system having call control means.
The present invention further relates to a cordless access subsystem for use in such a telecommunications system.
2. Description of the Related Art
A telecommunications system of this kind is known from the U.S. Pat. No. 5,418,838. The known system is comprised of a private automatic branch exchange having a cordless access subsystem. The branch exchange may be coupled to a public switched telecommunications network. A number of automatic branch exchanges may be coupled to form a network. The cordless access subsystem comprises a number of radio base stations or as called in a DECT (Digital European Cordless Telecommunications) system, radio fixed parts, clusters of which are coupled to each other via a backbone network in the branch exchange. In the known system, which is a microcellular cordless telephony system, for instance, the cordless terminal is allowed to roam locally. Handover of calls is done via the local backbone network. In other known systems, such as in GSM (Global System for Mobile Telecommunications), a mobile radio terminal is allowed to roam over a large geographical area. In GSM, the so-called Home/Visitor concept is applied in which at all registration locations the same standardised set of features is offered.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a telecommunications system in which a cordless terminal can always have access to all the network features it has the right to access from its subscription even though not all exchanges implement all network features.
To this end the telecommunications system is characterised in that the call control means comprise a call control agent at the side of the cordless access subsystem and a call control manager at the side of the network, whereby the call control agent is arranged to operate a call control protocol in which a call control setup message for an outgoing call from the cordless terminal is sent to a call control manager transport entity by a call control agent transport entity, which call control setup message comprises an information element indicating to the network the call control scenario to be carried out depending on the cordless terminal subscription. Herewith, call control can be done locally or remotely, depending on subscription.
In an embodiment of a telecommunications system according to the present invention, the information element comprises a globally unique operation value to be interpreted by the call control manager so as to accept or reject the call control setup message even if there is no call control manager transport entity, and operation parameters to be processed by the call control manager when it has not rejected an operation value. This makes it possible to attach cordless access subsystems operating according to the present invention to standard networks.
In an embodiment of a telecommunications system according to the present invention, the network is an ISDN network and the call control setup scenarios are local standard ISDN, local enhanced ISDN, and remote enhanced ISDN. In ISDN a lot of features are already standardized so that a varying package of features can easily be offered.
In an embodiment of a telecommunications system according to the present invention, when the scenario is remote enhanced ISDN, wherein the network comprises at least one further automatic branch exchange, the branch exchanges are coupled to each other at remote locations by means of an intervening network, the further branch exchange is a home branch exchange for the cordless terminal locked to the other branch exchange, and the call control manager is located in the further branch exchange so as to control the call from the remote cordless terminal. Present branch exchanges can cooperate with many different types of networks. So, for making the cordless access subsystems suitable for a different intervening network, only relative simple software has to be added thereto.
In an embodiment of a telecommunications system according to the present invention, the call control setup message further comprises a unique cordless terminal identification number from which the network derives routing of the call control setup message to the home branch exchange. Herewith, the network can find the right call control manager.
In an embodiment of a telecommunications system according to the present invention, the call control setup message comprises subscriber provided information including a call destination number and wherein the network temporarily stores the subscriber provided information, first sends the terminal identification number to the home branch exchange, and then, after having received acknowledgement from the home branch exchange that the cordless terminal is known in the home branch exchange, sends the stored subscriber provided information to the home branch exchange. Herewith, the interface between the cordless access subsystem is simpler because only a single acknowledgement is needed and reduced processing effort in the cordless access subsystem is needed.
In an embodiment of a telecommunications system according to the present invention, the call control setup message comprises subscriber provided information including a call destination number and wherein the network immediately sends the terminal identification number and the subscriber provided information to the home branch exchange. Herewith, the interface between the cordless access subsystem is simpler because only a single acknowledgement is needed and reduced processing effort in the network is needed.
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“The Open Book—A Practical Perspective on OSI” Marshall T. Rose, Prentice Hall 1990, pp. 19-48, 61-73, 85-97 and 125-131.
Slobod Jack D.
Smith Sheila
Trost William G.
U.S. Philips Corporation
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