Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
1999-11-15
2003-05-06
Le, Thanh Cong (Department: 2684)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C455S003010, C455S041300, C455S414200, C455S555000, C455S560000, C379S092030, C379S156000, C379S219000
Reexamination Certificate
active
06560464
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a telephone switching system, particularly a CENTREX (CTX) telephone switching system, in which CTX connections or CTX calls can be setup between defined CTX subscribers.
2. Description of the Related Art
CENTREX systems are purely software solutions that implement private branch exchanges connected to the public telephone network. CENTREX (CTX) groups can be used to replace hardware-implemented private branch exchanges (PBX) within each fixed network exchange (local exchange LE) of the public telephone network (public switched telephone network, PSTN). The advantage of this software CTX solution is that it allows the telephone terminal equipment previously employed for realizing private branch exchanges to continue to be employed, allowing a flexible adaptation/modification of the individual CTX groups. The subscribers of a CTX group (CTX subscribers) are directly connected to the respective exchange but have the feeling of belonging to a private network.
Specific CTX functions are offered to the CTX subscribers of a CTX group for the setup of CTX connections or for the switching of CTX calls; these functions are essentially similar to those functions that a subscriber connected to a hardware implemented private branch exchange is accustomed to. These CTX functions can comprise a private telephone number plan for the CTX subscribers, the selection of an operator, call redirection, call forwarding, implementing the exit code for exiting into the public network, and other functions. Furthermore, CTX additions beyond the standard functions or features are conceivable, such as call redirection which may be dependent on whether a call is internal to the group or comes from outside the group or is dependent on traffic restrictions (for example, blocking for calls from or into the public telephone network).
The CTX groups of a plurality of switching centers can form an overlapping CTX private network. An expanded ISUP signaling between the affected switching centers is employed for the control of the CTX functions that are offered in order to be able to transmit control information, such as the type of call or other features or functions (e.g., blocking).
The right-hand section of
FIG. 6
shows a simplified block circuit diagram of a known realization of a CTX system. In particular,
FIG. 6
shows a fixed network exchange
15
to which a wired or stationary CTX subscriber
8
is connected, All information required for CTX call processing are deposited in a data bank. This data bank comprises a CTX-specific subscriber database
13
as well as a CTX-specific group database
14
. Information about the CTX subscribers are deposited in the CTX-specific subscriber database, such as internal telephone numbers, external/public telephone numbers or CTX functions that are available to or, respectively, usable by the respective CTX subscribers.
Information about the individual CTX groups are stored in the CTX-specific group database
14
, which contains; among other things, a group number plan or predetermined group functions deposited in it that are available for the subscribers of the respective CTX groups.
Additionally, a traditional database
12
is provided for depositing the standard fixed network information that are required for call switching via the respective switching center
15
. This database
12
thus comprises generally public data, such as a number plan or a listing of the connected subscribers. A controller
9
, which is expanded by a control unit
10
for CTX-specific call processing, is provided for processing calls to be switched via the switching center
15
. This controller accesses the databases
12
through
14
via internal interfaces
11
in order to setup connections or to switch calls dependent on the information, stored in the respective database. In particular, the CTX control unit
10
accesses the two CTX-specific databases
13
,
14
and is exclusively responsible for processing CTX calls.
The left-hand section of
FIG. 6
shows a simplified block circuit diagram of a traditional mobile radio telephone system. A mobile radio telephone terminal equipment
1
communicates with a mobile radio telephone base station
2
(BS) that is allocated to a mobile switching center (MSC)
3
of a public mobile radio telephone network (public land mobile network PLMN). The mobile switching center
3
comprises a controller
4
for processing mobile radio telephone connections to the mobile terminal equipment
1
. This controller
4
accesses a temporary database
6
in which information about mobile subscribers is deposited, via internal interfaces
5
. This database comprises what is referred to as the visitor data file (visitor location register VLR) of the mobile switching center
3
; it may be utilized in GSM mobile radio telephone networks for supporting subscriber mobility.
Additionally, a permanent database
7
is provided that likewise stores information of the mobile subscribers contains the home data file (home location register (HLR)) in GSM mobile radio telephone networks. The visitor data file is coupled to the home data file of the mobile switching center
3
in order to be able to unambiguously identify the momentary location of a mobile subscriber. A home data file in which the mobile subscriber is registered is allocated to each mobile subscriber
1
.
When, however, the subscriber
1
is located outside the coverage area of the mobile switching center
3
allocated to him (e.g., when located abroad), it is determined that the corresponding mobile subscriber is not registered as a subscriber of the mobile switching center
3
. This determination is made after initially contacting the corresponding mobile terminal equipment
1
with the base station
2
allocated to the mobile switching center
3
. The mobile switching center having the corresponding home data file originally allocated to the mobile subscriber
1
is subsequently informed (via the fixed network) that the mobile subscriber is currently residing in the area of the new mobile switching center. Information that are necessary for encryption (among other things) are stored in the visitor data file of the new mobile switching center.
When the mobile subscriber
1
located outside the coverage area of his mobile switching center is called, a determination is made on the basis of the entry in his home data file that the called mobile subscriber is located in the area of the new mobile switching center and the connection is through-connected to him.
It can be particularly seen from the illustration of
FIG. 6
that completely different executive sequences for call processing as well as databases were previously provided for mobile subscribers
1
and CTX subscribers
8
. A parting wall that has not yet been satisfactorily overcome exists between the mobile radio telephone network shown at the left side and the fixed network with CTX subscribers shown at the right side, since mobile subscribers are not bound to a specific switching center, so that the CTX solution based on switching centers for a stationary CTX subscribers cannot be transferred without further effort to mobile CTX subscribers.
Although the field of intelligent network (IN) provides known solutions that combine wired or stationary subscribers with mobile subscribers, CTX functions can only be partially simulated utilizing such intelligent networks. A complete utilization of the entire scope of CTX functions, such as the billing according to reduced fee schedules for private networks, is not possible.
Additionally, a relatively complicated adaptation of the central TN network A element referred to as “service control point” (SCP) as well as an administration of the individual subscribers in the switching centers and this central IN network element is required given such IN solutions.
Furthermore, it is already known to forward calls from a CTX switching center, i.e., from the switching center
15
in
FIG. 6
, into the public mobile radio telephone
Egger Franz
Klotz Udo
Rau Helmut
Schneider Bernd
Cong Le Thanh
D'Agosta Stephen
Shaw Pittman LLP
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