Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-07-30
2003-09-23
Vo, Nguyen T. (Department: 2685)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S433000, C455S435100
Reexamination Certificate
active
06625453
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to telecommunications in general, and, more particularly, to a technique for setting up a wireless telecommunications call across a regional or political boundary.
BACKGROUND OF THE INVENTION
FIG. 1
depicts a schematic diagram of a portion of a typical wireless telecommunications system in the prior art, which system provides wireless telecommunications service to a number of wireless terminals (e.g., wireless terminals
101
-
1
through
101
-
3
) that are situated within a geographic area. The heart of a typical wireless telecommunications system is Wireless Switching Center (“WSC”)
120
, which is sometimes also known as a Mobile Switching Center (“MSC”) or a Mobile Telephone Switching Office (“MTSO”). Typically, Wireless Switching Center
120
is connected to a plurality of base stations (e.g., base stations
103
-
1
through
103
-
5
) that are dispersed throughout the geographic area serviced by the system and to the local and long-distance telephone and data networks (e.g., local-office
130
, local-office
138
and toll-office
140
). Wireless Switching Center
120
is responsible for, among other things, establishing and maintaining calls between wireless terminals and between a wireless terminal and a wireline terminal (e.g., wireline terminal
150
), which is connected to the system via the local and/or long-distance networks.
The geographic area serviced by a wireless telecommunications system is partitioned into a number of spatially distinct areas called “cells.” As depicted in
FIG. 1
, each cell is schematically represented by a hexagon; in practice, however, each cell usually has an irregular shape that depends on the topography of the terrain serviced by the system. Typically, each cell contains a base station, which comprises the radios and antennas that the base station uses to communicate with the wireless terminals in that cell and also comprises the transmission equipment that the base station uses to communicate with Wireless Switching Center
120
.
For example, when wireless terminal
101
-
1
desires to communicate with wireless terminal
101
-
2
, wireless terminal
101
-
1
transmits the desired information to base station
103
-
1
, which relays the information to Wireless Switching Center
120
over wireline
102
-
1
. Upon receipt of the information, and with the knowledge that it is intended for wireless terminal
101
-
2
, Wireless Switching Center
120
then returns the information back to base station
103
-
1
over wireline
102
-
1
, which relays the information, via radio, to wireless terminal
101
-
2
.
Because a wireless terminal is mobile, it can be served by different base stations as it moves. In fact, if a wireless terminal moves a substantial distance it can be serviced by another wireless switching center and its satellite base stations rather than by the wireless terminal's “home” wireless switching center.
For example,
FIG. 2
depicts a flowchart of a method in the prior art, which involves the interaction of three wireless switching centers (calling WSC
201
, visiting WSC
202
and home WSC
203
) and two wireless terminals (wireless terminal
211
and wireless terminal
212
) as a call is established from wireless terminal
211
to wireless terminal
212
.
Calling WSC
201
, visiting WSC
202
and home WSC
203
are each conventional wireless switching centers as well-known to those skilled in the art. In the example in
FIG. 2
, calling WSC
201
and visiting WSC
202
are in the same region (or country) and both are in a different region (or country) than is home WSC
203
. For example, calling WSC
201
and visiting WSC
202
might be in northern Illinois and home WSC
203
might be in Seoul, Korea.
For the purposes of this specification, the word “region” is defined as one or more geographic areas that are: (1) owned or operated by the same entity, or (2) administered by the same regulatory body. For the purposes of this specification, the word “country” is defined as a primary political unit (e.g., the United States, Canada, the United Kingdom, Japan, etc.) or a subprimary political unit (e.g., New Jersey, Alberta, Wales, Okinawa, etc.).
Wireless terminal
211
is a conventional wireless terminal that is currently served by calling WSC
201
. It is irrelevant to whether wireless terminal
211
is being served by its home wireless switching center or is roaming and being served by another wireless switching center.
Wireless terminal
212
is a conventional wireless terminal whose home wireless switching center is home WSC
203
. Therefore, home WSC
203
has associated with it a home location register or “HLR” (not shown) that maintains a database that includes the identity of the wireless switching center that is serving wireless terminal
212
at any given time when wireless terminal
212
is roaming.
When wireless terminal
211
desires to place a call to wireless terminal
212
, it begins at step
231
by placing the call via calling WSC
201
. As part of step
231
, wireless terminal
211
provides an indicium (e.g., the telephone or directory number, etc.) of the identity of wireless terminal
212
to calling WSC
201
so that calling WSC
201
can determine how and where to direct the call. Calling WSC
201
analyzes the indicium, in well-known fashion, to determine that the home wireless switching center of wireless terminal
212
is home WSC
203
.
Therefore, at step
232
, calling WSC
201
transmits a call set-up message to home WSC
203
to indicate that calling WSC
201
desires to establish a call with wireless terminal
212
, whom both calling WSC
201
and home WSC
203
know has home WSC
203
as its home wireless switching center. Typically, the call set-up message from calling WSC
201
to home WSC
203
comprises: (1) an indicium (e.g., the telephone or directory number, etc.) of the identity of wireless terminal
201
(e.g., for caller ID purposes, for billing purposes, etc.), and (2) an indicium (e.g., the telephone or directory number, etc.) of the identity of wireless terminal
202
(for routing purposes).
As part of step
232
, home WSC
203
queries its home location register and determines that wireless terminal is currently being served by visiting WSC
202
.
Therefore, at step
233
, home WSC
203
transmits another call set-up message to visiting WSC
202
to indicate that calling WSC
201
desires to establish a call with wireless terminal
212
.
Upon receipt of the call set-up message, visiting WSC
202
completes the call at step
234
to wireless terminal
212
so that wireless terminal
211
and wireless terminal
212
can communicate. Although wireless terminal
211
and wireless terminal
212
might be only a few miles apart, the call between them crosses a regional or political boundary twice! Therefore, if there are tariffs or surcharges on calls crossing regional or political boundaries the call between wireless terminal
211
and wireless terminal
212
could be horrendously expensive. Furthermore, large long-distance charges could apply for the call. Therefore, the need exists for reducing the tariffs, surcharges and long-distance charges that might be incurred for calls involving wireless switching centers in multiple regions (or countries).
SUMMARY OF THE INVENTION
Some embodiments of the present invention are capable of reducing, or even eliminating, the tariffs, surcharges and long-distance charges that might be incurred for calls involving wireless switching centers in multiple regions (or countries). This is accomplished in the illustrative embodiment by trunking calls directly from the calling wireless switching center to the visiting wireless switching center, where advantageous, without trunking the call across a regional or political boundary, as is done in the prior art.
The illustrative embodiment of the present invention comprises: receiving at a first wireless switching center a first call set-up message from a second wireless switching center; transmitting, in response to the first call set-up message,
Dai Weiqian
Nguyen Tony Tuong
Lucent Technologies - Inc.
Nguyen Thuan T.
Vo Nguyen T.
LandOfFree
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