Telecommunications – Radiotelephone system – Special service
Reexamination Certificate
1999-07-30
2004-08-24
Tran, Cong Van (Department: 2683)
Telecommunications
Radiotelephone system
Special service
C455S433000, C455S445000
Reexamination Certificate
active
06782254
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to telecommunications in general, and, more particularly, to a technique for forwarding 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. Furthermore, if the serving wireless switching center is in a different region or country than the wireless terminal's home wireless switching center, this can cause the serving wireless switching center to fail to provide the correct service to the wireless terminal.
For example,
FIG. 2
depicts a flowchart of a method in the prior art, which involves the interaction of two wireless switching centers (originating WSC
211
and serving WSC
213
), home location register
212
, and two wireless terminals (wireless terminal
201
and wireless terminal
202
) as the wireless switching centers and home location register
212
attempt to establish a call from wireless terminal
201
to wireless terminal
202
.
Originating WSC
211
and serving WSC
213
are each conventional wireless switching centers. Typically, home location register
212
and serving WSC
213
are in different regions (or countries) and serving WSC
213
and wireless terminal
202
are in the same region (or country). For example, home location register
212
might be in northern Illinois and serving WSC
213
and wireless terminal
202
might be in Seoul, Korea. It is irrelevant whether originating WSC
211
is in the same region (or country) as either home location register
212
or serving WSC
213
. Home location register
212
, might be, but is not necessarily, associated with originating WSC
211
.
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
201
is typically a conventional wireless terminal that is currently served by originating WSC
211
. It is irrelevant whether wireless terminal
201
is being served by its home wireless switching center or is roaming and being served by another wireless switching center.
Wireless terminal
202
is typically a conventional wireless terminal whose home location register is home location register
212
. Home location register
212
comprises a database that includes:
i. the identity of the wireless switching center that is serving wireless terminal
202
at any given time (in this case serving wireless switching center
213
); and
ii. at least one forward-to number for wireless terminal
202
, which forward-to number might or might not include a “country-code” or international dialing prefix.
For the purpose of this specification, a “forward-to number” for a wireless terminal is defined as the number to which an incoming call to the wireless terminal is forwarded if, for some reason, the incoming call cannot be completed to the wireless terminal. Typically, the forward-to number is associated with an answering machine.
As shown in
FIG. 2
, wireless terminal
202
is roaming and is currently being served by serving WSC
213
. When wireless terminal
202
first enters the area served by serving WSC
213
, wireless terminal
202
registers with serving WSC
213
, and serving WSC
213
sends a message to home location register
212
indicating that wireless terminal
202
is currently being served by serving WSC
213
. By sending a message to home location register
212
indicating that wireless terminal
202
is currently being served by serving WSC
213
, serving WSC
213
enables home location register
212
to know where wireless terminal
202
is at any moment.
In steps
221
through
227
originating WSC
211
, home location register
212
and serving WSC
213
attempt to set-up a call to wireless terminal
202
. But if wireless terminal
202
is unavailable to receive the call, for any reason, serving WSC
213
seeks, in steps
228
and
229
, a “forward-to” number from home location register
212
where the call can be forwarded. Such a number might represent an automatic answering system. But where home location register
212
and serving WSC
213
are in different regions (or countries), the forward-to number provided to serving WSC
213
might or might not have the proper international country code prefix and might be erroneously forwarded by serving WSC
213
as an national call, or might be erroneously forwarded as an international call. Furthermore, if the forward-to number is provided as a national number without an international country code prefix, but is to be associated with a another nation, then serving WSC
213
cannot complete the call properly.
Therefore, the need exists for a technique for properly forwarding calls for wireless terminals that are roaming across regional and political boundaries.
SUMMARY OF THE INVENTION
Some embodiments of the present invention are capable of forwarding a call properly for a wireless terminal when the wireless terminal is roaming in a different region (or country) than where its home location register resides. In particular, this is accomplished by having the home location register and
Chambers Michael Dwayne
Dai Weiqian
Lee Chee Keong
Nguyen Tony Tuong
Lucent Technologies - Inc.
Tran Cong Van
LandOfFree
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