Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-07-01
2002-11-26
Trost, William (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C445S060000, C445S060000, C379S220010, C379S221100
Reexamination Certificate
active
06487412
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to telecommunication networks and, more particularly, to a method and system for routing calls directed to wireless directory numbers in a telecommunications network.
2. Background of the Art
In the present telecommunications networks, a wireline telephone number or directory number (DN) is associated with a fixed geographic location and is served by a single wireline switch. A wireless DN, however, is associated with multiple geographic locations and is served by any one of a number of wireless switches depending on the specific geographic location of the associated wireless device at the time a call is made. This portability of a wireless DN is one of the basic attributes of wireless telephony.
A pair of home location register and visited location register in a telecommunications network provide seamless roaming when a call is placed to or from a wireless DN. A home location register is associated with a home wireless switch where a wireless DN resides (i.e., the wireless switch to which all incoming calls to the wireless DN are directed). A wireless device is located within its home area when the wireless device can directly communicate with its associated home wireless switch (i.e., located in the area covered by the home wireless switch).
A visitor location register is associated with a wireless switch currently serving a wireless device that is outside of its home area. A wireless device is outside of its home area (or roams) when the wireless device cannot directly communicate with the home wireless switch and instead communicates with another wireless switch, which is referred to as a visited wireless switch.
One problem with the present telecommunication networks is that two connections must be established when a call is placed to a wireless DN whose associated wireless device is outside of its home area. In such instances, the telecommunications network first establishes a connection to the home wireless switch associated with the wireless DN. The home wireless switch then establishes a second connection to a visited wireless switch that currently serves the wireless DN.
As an illustration,
FIG. 1
shows a block diagram of a conventional telecommunications network
100
. Telecommunications network
100
comprises a wireline switch
110
, a home wireless switch
120
, a home location register
130
, a signal transfer point (STP)
135
, a visitor location register
140
, a visited wireless switch
150
, a wireline telephone
155
, antenna
170
, and a wireless device
175
.
Typically, a wireline subscriber using telephone
155
initiates a call request
180
a
by dialing the wireless DN associated with wireless device
175
. When wireline switch
110
receives call request
180
a,
wireline switch
110
establishes a first connection
180
b
via a Public Switched Telephone Network (PSTN)
160
to home wireless switch
120
, which is the home switch associated with the dialed DN.
Home wireless switch
120
sends an “Interim Standard 41” (IS-41) route_request message
180
c
to its associated home location register
130
, requesting the current location of wireless device. The IS-41 standard is described in “Radio Telecommunications Intersystem Operations,” ANSI/TIA/EIA/41-D-1997, which is incorporated herein by reference. The IS-41 standard describes the communication protocol between home wireless switch
120
, home location register
130
, visitor location register
140
, and visited wireless switch in telecommunications network
100
.
If wireless device is outside of its home area as shown in
FIG. 1
, home location register
130
then identifies the visitor location register with which wireless device
175
last registered, for example visitor location register
140
, and sends an IS-41 route_request message
180
d
via STP
135
to visitor location register
140
.
Visitor location register
140
forwards route_request message
180
d
to its associated visited wireless switch
150
, requesting a route to wireless device
175
. Visited wireless switch
150
computes a temporary local directory number (TLDN), which can be used in establishing incoming calls to wireless device
175
. Visited wireless switch
150
then returns the TLDN to visitor location register
140
in an IS-41 message
180
e.
Visitor location register
150
then sends via STP
135
to home location register
130
an IS-41 route_request_response message
180
f
that includes the TLDN.
Home location register
130
forwards route_request_response message
180
f
to home wireless switch
120
. Using the TLDN in route_request_response message
180
f,
home wireless switch
130
then establishes a second connection
180
g
to visited wireless switch
150
, which sends a ring signal to wireless device
175
. Thus, to establish a call between telephone
155
and wireless device
175
when wireless device
175
is outside of its home area, telecommunications network
100
must establish two separate connections
180
b
and
180
g.
SUMMARY OF THE INVENTION
It is therefore desirable to have a method and system for reducing the number of connections that must be established in a telecommunications network when connecting a call to a wireless device that is located outside of its home area.
Methods and systems consistent with the present invention establish a call to a wireless DN in a telecommunications network by identifying a signaling node associated with the wireless DN, determining, at the signaling node, a route that excludes the home node associated with the wireless DN when the associated wireless device is outside of its home area, and establishing a connection via the determined route to a visited node in the network that currently serves the wireless DN.
In one embodiment, a first node receives a call request directed to a wireless DN when the wireless device associated with the wireless DN is outside of its home area. The first node invokes a trigger that identifies a signaling node associated with the wireless DN and requests from the signaling node a route for establishing the call to the wireless DN. The signaling node then determines a route that does not include the home node associated with the wireless DN. The first node then establishes via the determined route a single connection to a visited node serving the wireless DN. Accordingly, the telecommunications network establishes the call to the wireless DN without establishing a connection to the home node.
This summary and the following description of the invention should not restrict the scope of the claimed invention. Both provide examples and explanations to enable others to practice the invention.
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Brennan Stephen P.
Dellangelo Michael
Howe Walter Wesley
Petrey Michael J.
GTE Wireless Service Corporation
Nguyen Simon
Trost William
Weixel James K.
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