Telecommunications – Radiotelephone system – Special service
Reexamination Certificate
1999-11-16
2002-05-14
Le, Thanh Cong (Department: 2684)
Telecommunications
Radiotelephone system
Special service
C455S413000, C455S445000
Reexamination Certificate
active
06389279
ABSTRACT:
FIELD OF INVENTION
This invention relates to a telephone communications system enabling call redirection for subsequent call events.
BACKGROUND OF THE INVENTION
With telephone communications systems, services may require call redirection to an alternate call destination dependent upon events that occur during the duration of the call. With the current state of the art, the initiation of the call redirection is caused by a call event that has already occurred. The prior art supports call redirection in one of three ways. The most common approach is to “camp on” the call by “hairpinning” the call through an adjunct processor using telephone facilities. This enables the adjunct processor to monitor the call throughout the duration of the call. However, hairpinning can add substantial cost to the service because additional transmission facilities are required. If a specified call event is detected by the adjunct processor, the adjunct processor instructs the telephone switching center to establish another call to a specified call destination.
With the second approach, hairpinning is not utilized. Rather, a call between a telephone unit and an adjunct processor is established. From the dialog that occurs during the call, the adjunct processor determines that the call should be redirected to another telephone designation. A connection is established from the telephone unit and the telephone designation. At this time, the adjunct processor is not involved with the call and thus is not active in subsequent call processing.
With the third approach, a call between a telephone unit and an adjunct processor is established, enabling dialog between the adjunct processor and the telephone unit to occur. The call is consequently redirected to another telephone designation. Moreover, the adjunct processor sends an enabling trigger to the telephone switching center over a control link. If the specified call event occurs, the telephone switching center sends a query message over the control link to the adjunct processor, asking for the appropriate action to be taken. The adjunct processor responds with a redirection message that contains a specified call destination.
FIG. 1
corresponds to the hairpinning approach (the above-described first approach) and illustrates an architecture as embodied in prior art for attaching adjunct processor
103
to mobile switching center (MSC)
102
in order to provide wireless services. In this architecture, mobile subscriber unit
100
is provided services by MSC
102
through base station
101
. Mobile subscriber unit
100
communicates with base station
101
over radio channel
106
requesting a call. Both control messages as well as voice transmission are supported by radio channel
106
. Voice transmission is supported over facility
107
to a switching fabric contained in MSC
102
. Adjunct processor
103
monitors and relays voice transmission to public switching telephone network (PSTN)
104
over facility
108
to facility
109
. PSTN
104
establishes a voice connection to designated party
105
according to dialed digits entered by either mobile subscriber unit
100
or designated party
105
thus completing the call.
Adjunct processor
103
can reside at one of a number of network entities that are associated with a wireless intelligent network, including an intelligent peripheral (IP), a service node (SN), or a service control point (SCP). The IP performs specialized resource functions such as playing announcements, collecting digits, performing speech-to-text or text-to-speech conversions, recording and storing voice messages, and so forth. The SCP is a real-time database and transaction processing system that provides service control and service data functionality. The SN combines the capabilities of an IP and an SCP.
If adjunct processor
103
detects that a particular call event occurs during the call between mobile subscriber unit
100
and party
105
, such as a disconnect indication from party
105
, adjunct processor
103
issues control redirection message
110
to PSTN
104
to reconfigure a voice path between mobile subscriber unit
100
and party
111
. Redirection message
110
is typically transported on a separate control link. PSTN
104
subsequently establishes a voice path through PSTN
104
to party
111
.
FIG. 2
corresponds to the above described second approach and illustrates a wireless communications architecture utilizing a redirection directive in accordance with prior art. Mobile subscriber unit
120
communicates with base station
121
over radio channel
126
requesting a call. Voice transmission is supported over facilities
127
and
128
to adjunct processor
123
through MSC
122
. Consequently, a full-duplex connection is established between a user of mobile subscriber unit
120
and adjunct processor
123
, from which it is determined that the call should be redirected to telephone unit
125
. Adjunct processor
123
sends redirection message
130
to MSC
122
, instructing MSC
122
to establish voice connection
129
through PSTN
124
to party
125
and to remove voice connection
128
. Thus, a voice path is completed between mobile subscriber unit
120
and party
125
. At this time, adjunct processor
123
is no longer active with the call.
FIG. 3
corresponds to the above described third approach and illustrates an architecture using a two-stage approach as embodied in prior art for attaching adjunct processor
152
to landline switching center
151
in order to provide landline telephone services. With landline advanced intelligent networks, landline switching center
151
is typically identified as a service switching point SSP. In this architecture, telephone unit
150
is provided service by telephone switching center
151
. However, as appreciated by one skilled in the art, this architecture is applicable to wireless services by incorporating a plurality of base stations, replacing landline switching center
151
with a mobile switching center, and utilizing mobile subscriber units as telephone units. Moreover, the term “telephone unit” is applicable to a variety of telephone instruments including wired telephone sets, cordless telephones, mobile subscriber units, fixed wireless telephone sets and so forth.
In
FIG. 3
, telephone unit
150
communicates with landline switching center
151
, requesting a call. This request is physically conveyed by a signal, which can be a digital message, on facility
156
. Moreover, facility
156
also transports voice transmission once the call is established. Landline switching center
151
completes the call to party
154
over facility
157
through PSTN
153
. Adjunct processor
152
is notified of the call by landline switching.center
151
by sending message
158
to adjunct processor
152
. Messages
158
,
159
,
160
, and
161
are transported on a control link between landline switching center
151
and adjunct processor
152
.
Adjunct processor
152
arms landline switching center
151
in order to prepare landline switching center
151
for the possibility of a subsequent call event identified in arm event message
159
. For advanced intelligent networks, arm event message
159
is specified as the Request_Report_BCM_Event message in Bellcore GR-1298-CORE and GR-1299-CORE, Issue 4, Revision 1, October 1998, pages 4-1 to 4-15 (SSP Processing of Triggers and Requested Events). Landline switching center
151
continues to process and monitor the call until the call event as specified in arm event message
159
occurs. If the call event occurs, landline switching center
151
stops processing, sends event query message
160
to adjunct processor
152
, and waits for response message
161
from adjunct processor
152
. GR-1298 and GR-1299 specify the event query message as the EDP-Request message for advanced intelligent networks. Adjunct processor
152
returns response message
161
, which instructs landline switching center
151
about subsequent action, such as redirecting the call to a different party.
The present invention obviates the need for the adju
Calabrese Robert Thomas
Thompson Robin Jeffrey
Zahnle Jeffrey Arthur
Zurawski Robert John
Cong Le Thanh
Johannesen Michael B.
Lucent Technologies - Inc.
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