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FIELD OF THE INVENTION
This invention relates generally to the arrangement of conference telephone
calls, and, in particular, to a system and method for optimizing the
manner in which conference calls, particularly those involving
international locations, are arranged or initiated.
BACKGROUND OF THE INVENTION
The virtual explosion in growth of multi-national companies has led to a
dramatic increase in international telecommunications traffic. A
significant, and ever increasing part of such traffic is devoted to
conference calls, i.e., calls involving three or more parties. The manner
in which such conference calls are arranged or initiated depends, among
other factors, upon the type of terminal equipment available to the
participants. Thus, if one of the participants has a two-line (or
multi-line) capability, that party can place one call, put it on hold,
place a second (or subsequent) call, and then bridge the two (or more)
calls. If two or more participants have the same capability, then one
participant can make all of the calls, or several participants can add one
or more additional individuals to the conference, thereby in effect
sharing the responsibility for initiating the conference among the
parties.
The choice of which approach to take is not today made with any degree of
consistency nor with any consideration of the advantages that may be
obtained if one conference initiation approach is selected over another.
In particular, it may turn out that the cost of making a call from point A
to point B is less than the cost of making the same call from point B to
point A, simply because of the time zone differences at those locations
and the fact that the cost of making a call is time sensitive (e.g.,
evening or night rates are typically cheaper than day rates). "Direction
dependent" rates are almost always encountered when international long
distance calls are involved. It may also turn out that more (or better
quality) circuits are available for telecommunications traffic destined
for a foreign country as opposed to the circuits connecting the same
endpoints but originating from locations outside of this country.
The situation described above is also true with respect to conference calls
made using a conference facility (such as the Alliance Conference Bridge
Service available from AT&T) that is located within the telecommunications
network and controlled by the telecommunications provider, rather than by
using customer premise equipment. In instances in which network based
conference bridges are used, there are nevertheless choices that should be
made to improve economy and efficiency: which participant should set up
the call, which bridge location should be selected as a dominant location,
what time the call should be placed, and so on.
SUMMARY OF THE INVENTION
In accordance with the present invention, the initiator of a conference
call provides conference requirements such as number and location of
parties to be conferenced, time for beginning and end of conference, and
telecommunications facilities requirements (e.g., bandwidth requirements
for video and multi-media calls), to a conference optimization system
(COS). The COS compares the requirements with information in a database,
including (a) the cost for each of the paths/routes at the desired time
for the conference, (b) available network paths/routes, taking into
account the required bandwidth and quality of transmission, and (c)
capabilities of the terminal equipment available to the participants. The
COS uses a processor such as a microprocessor to identify available
network paths/routes for the conference (advantageously with real time
input from telecommunications network operations and maintenance systems),
select the most cost effective means for initiating the conference, and
send information, such as an announcement, to the parties involved in the
conference, indicative of the route/path selection. In a preferred
embodiment, the information required for conference initiation is provided
to a network call controller in order to actually set up the conference
without further intervention by the participants. The COS can be used in
conjunction with and/or be part of a public telecommunications network, or
alternatively be used in and/or be part of a global private
telecommunications network.
BRIEF DESCRIPTION OF THE DRAWING
The present invention will be more fully understood by consideration of the
following detailed description, which should be read in light of the
accompanying drawing in which:
FIG. 1 is an overall block diagram of a system arranged in accordance with
the principles of the present invention to optimize the initiation of
multiparty conference calls;
FIGS. 2-5 illustrate possible topologies for multi-location conference
calls;
FIG. 6 is a flow diagram illustrating the process followed in processor 112
of FIG. 1 in order to optimize and then initiate, a multi-location
conference call;
FIG. 7 is a flow diagram illustrating in more detail the process followed
in the optimization calculation, step 613 in FIG. 6;
FIG. 8 is a flow diagram illustration an alternative process for
optimization calculation;
FIG. 9 is a diagram illustrating the fore, at of a typical record stored in
database 116 of FIG. 1; and
FIG. 10 is a diagram illustrating the manner in which a call requesting
conference optimization can be routed to COS 110 from a domestic location
and from a foreign location.
DETAILED DESCRIPTION
Referring first to FIG. 1, there is shown an overall block diagram of the
interrelationship between multiple locations 101-104 wishing to
participate in a teleconference, and a conference optimization system 110
arranged in accordance with the principles of the present invention to
optimize the initiation of the conference calls. Locations 101, 102 and
103 include customer equipment such as a telephone or videophone terminal
located in a first country, while location 104 includes terminal equipment
such as a telephone located in a foreign location. Each of the locations
101-104 is linked to a particular network element in a communications
network designated generally as 120. Thus, location 101 is connected to a
first switch 131, location 102 is connected to a second switch 132,
location 103 is connected to a third switch 133, and location 104 is
connected to yet a fourth switch 134, which may be an international
gateway switch. Switches 131, 132 and 133 are interconnected with each
other, while switch 134 is connected to switch 132. All switches are
connected to a signaling network designated generally as 135. The
aforementioned network elements, which are part of an interconnected
collection of network elements designated generally as 130, are
conventional in nature and individually and collectively well known to
persons skilled in the art in terms of description and operation. Elements
130 can be part of the common carder network provided by AT&T, in which
case switches 131-133 can be #4ESS.TM. electronic switches, while
signaling network 135 can be a packet switched communication network for
signaling messages, such as AT&T's common channel signaling system (CCS7)
network.
Communications network 120 may include one or more facilities for setting
up multi-party conferences, such as a conference bridge 137, which is
shown connected to switch 133. The function of bridge 137 is to
interconnect multiple call legs that are extended to the bridge from
various locations. The arrangement and internal operation of a conference
bridge is well known to persons skilled in the art. This equipment can be
obtained from various vendors such as the Transvox System from Alcatel,
the Digital Conference Switching System from AT&T and the Meridian MS-1
System from Northern Telecom.
Communications network 120 may also include one or more network
control/management centers 139, which are connected to each of the
switches 131-134, and which monitor the operation of the switches and can
respond dynamically to changing network traffic conditions. These systems
are used for performing Operation, Administration, Maintenance and
Provisioning (OAM&P) functions for the network elements.
In accordance with this invention, communications network 120 includes a
conference optimization system (COS) 110 arranged to select a particular
configuration for network elements 130 that is most efficient to enable
conference communications between participants at locations 101-104. For
this purpose, COS 110 includes a central processor 112, which may be a
microprocessor or microcomputer arranged to operate under control of
program instructions (described below in connection with FIG. 7) stored in
a first database 114. A voice processing unit 113, described further
below, is connected to processor 112 and is available to play appropriate
messages to persons using the system, and to receive information input to
the COS from such users. Data used in the process performed in processor
112 is stored in a second database 116 connected to processor 112. Typical
records stored in database 116 are described in connection with FIG. 9.
COS 110 can be linked to network elements 130 in several ways. As shown in
FIG. 1, a data communications path 122 links signaling network 135 with
processor 112 via an interface system 118, which is arranged to perform
any necessary signal and/or format conversion. Alternatively or in
addition, switches 131-134 (as well as network control/management center
139) may be linked directly with interface 118 in COS 110 over packet data
links, designated 124 in FIG. 1.
FIGS. 2 through 5 illustrate the different topologies in which five
locations 201-205 can be interconnected with a conference bridge 210 to
form a conference call. In these figures, it is assumed that each of the
five locations is connected to a different one of network elements 130,
for example, to a different switch. This assumption is generally valid for
conference calls in which at least some of the parties in file conference
are situated at geographically dispersed locations. Note that if all of
the parties in a conference are served by, and/or connected to the same
network element, there is, generally speaking, no way of optimizing a
conference between such locations. If some of the parties in a conference
at a "first location" are served by the same network element, and other
parties at different locations are served by different network elements,
then the former parties can be "grouped" for the purposes of optimization
and considered as a single location, with the present invention then being
applicable to (a) the remaining locations and (b) the first location.
In FIG. 2, a call-in or inward star configuration is shown. In this
arrangement, each location 201-205 on the conference calls the single
conference bridge 210. In FIG. 3, a call-out or outward star is shown. In
this arrangement, an operator or conference originator at conference
bridge 210 calls each of the other locations 201-205 on the conference. In
FIG. 4, a mixture of the topologies of FIG. 2 and 3 is shown. Here, an
operator or conference originator at conference bridge 210 calls some of
the locations, e.g., locations 201 and 202, while the other locations
203-205 call into the conference bridge 210. The decision as to which
locations call in and which locations are called can strongly affect
service availability and economics of the conference.
FIG. 5 is a generic topology. Here, there is no conference bridge. Instead,
certain locations call other locations, such that a path is established
which connects all locations. This topology is the most flexible and
relies on call bridging capabilities provided within the locations
themselves. These capabilities are currently available in many different
types of sophisticated customer premises equipment. The arrangement of
FIG. 5, in general, provides the lowest usage based cost for a conference
call. However, the method by which the topology is chosen must be
carefully determined, as set forth below.
In accordance with the invention, the steps performed by processor 112 in
order to optimize (and thereafter initiate) a multi-location conference
call, are illustrated in FIG. 6. The process, under the control of
programs stored in database 114, begins in step 601, in which a call is
received in processor 112 requesting conference optimization and/or
initiation. The manner in which a call is .routed through network 120 is
described in more detail below, in connection with FIG. 10. In step 603,
information describing the requirements for the desired conference are
obtained from the party placing the call, and stored temporarily in
database 116. The information obtained in step 603 includes data
describing the number and identity of the particular locations to be
included in the conference call (e.g., all of the destination telephone
numbers), the desired start time of the conference call, the expected
duration of the call, and any special telecommunications requirements for
the call. In the latter category, for example, would be requirements for a
multimedia conference that includes not only voice but also still frame
images and/or motion t.v., and data requirements if graphics presentations
are to be part of the conference arrangements. Also for certain
conferences, packet communications using satellite transmission facilities
may be adequate; in other conferences, delay may be unacceptable, so that
terrestrial as opposed to satellite based transmission facilities may be
necessary. Other information input to processor 112 in step 601 may
include terminal identification information and/or characteristics, (e.g.,
model numbers of specific available CPE or feature information for
particular models) potential bridge locations, tariff information, usage
sensitive rates based on bandwidth, origin, destination and time of day,
and allowed conference topology.
In step 605, the information obtained in the conference set up request in
step 603 is validated, to determine that, for example, the individual
requesting the conference is authorized to do so, and that the specific
locations for the conference are represented by valid telephone numbers.
Validation is performed through suitable look-ups in database 116. This
step may also involve sending a query to, and receiving a response from,
network control/management center 139. This is done, for example, so that
information is available in COS 110 indicating if some potential
arrangements for the conference are busy or suffering degradations. If
some or all of the information is determined to be invalid in step 607, an
announcement is played in step 609, requesting that the information be
corrected and re-entered. Steps 603, 605 and 607 are then repeated. The
announcement is formulated in voice processing unit 113 attached to
processor 112, and supplied to the user requesting the conference via
interface 118.
If it is determined in step 607 that the information received in step 603
is valid, additional information needed for conference optimization and/or
setup is retrieved from database 116 in step 611. For example, specific
charges involved in a call from a first location to a second location, and
from the second location to the first location, are each determined, using
stored tariff information available in database 116. The specific stored
information retrieved from database 116 may depend upon time of day
information available in processor 112. The same procedure is followed for
each set of call legs, that is, for calls between all of the other
locations which may serve as origination points or endpoints for the
conference. The information retrieved in step 611 is then utilized in step
613 to actually calculate optimized conference characteristics, such as by
minimizing the total cost for all legs of the conference call. A more
detailed view of the calculation process performed in step 613 is given
below, in connection with the description of FIG. 7.
In step 615, a determination is made as to whether call setup was requested
by the party setting up the conference in step 601. If so, the parameters
needed to actually complete the call are output from processor 112 and
applied to network elements 130 via interface 118 in step 617. If not, an
announcement is formulated in voice processing unit 113 in step 619,
containing verbal information useful in optimizing the conference setup.
This information will inform the caller as to the most cost effective
arrangement for initiating the conference. In either event, a bill setting
forth the charges incurred during the optimization processing may be
prepared in step 621, and transmitted to network elements 130 in a manner
similar to that used to bill for other toll charges. Note that if the
invention is used in a global private network environment, the bill
prepared in step 621 may be replaced by a "usage record", which can
provide valuable information for internal telecommunications management.
The process of FIG. 6 is then terminated in step 623.
Referring now to FIG. 7, details of the optimization calculation of step
613 are illustrated. The process begins in step 701, in which one or more
topologies, such as those illustrated in FIGS. 2-5, are selected for the
conference. Selection is based upon several factors, chiefly including the
capabilities of the locations from which the calls will be originated. If
several topologies can be used, each one is identified.
In step 703, potential conference designs are formulated for each available
conference topology. For example, in the topology of FIG. 4, certain
locations can originate call legs while other locations can receive calls
from the conference bridge. Design formulation takes account of
information previously retrieved from network control/management center
139, indicating, for example, that a particular transmission path or
network system is overloaded or is providing degraded performance. For
each potential design, the cost (or other factors, as discussed below) is
computed in step 705, using information retrieved in step 611 of FIG. 6.
As explained in more detail below, the cost may be thought of as a
summation of the cost of individual call legs, or, alternatively, other
computations may be performed. Note that the cost of making a call from
the first location in a pair of locations to the second one of the
locations in the same pair of locations can be different from the cost of
making a call from the second location in the pair of locations to the
first one of the locations, due to differences in the pricing of
international calls, time zone differences, available discounts, and so
on. Accordingly, both costs, i.e., for call originations in both
directions, are computed individually. In step 707, the computed cost is
compared with a cost previously stored during a previous iteration of the
process of FIG. 7. If the computed cost is less than the stored cost, the
computed cost is stored in database 116 in step 711. (For the initial
iteration, the stored cost is assumed to be infinitely high, so that a
positive result is always obtained in step 709 for this iteration.) If the
computed cost is not less than the stored cost, or when step 711 is
completed, a determination is made as to whether additional conference
designs are to be evaluated. If so, the process of FIG. 7, steps 703 to
713, is repeated. If not, the design parameters corresponding to the
optimum design are output in step 715, and the optimization computation
process terminated.
As noted above, factors other than cost of the conference may be calculated
and optimized in the process of FIG. 7. Such factors may include, by way
of example, the set-up delay in providing a conference for a large number
of conferees, or the "quality" of the facilities available for a
multimedia conference. In any of these events, the process of FIG. 7 is
essentially the same: the characteristics of the available design options
are translated to equivalent numerical values, and the values are
optimized, by maximizing (or minimizing) the appropriate variable.
While the process of FIG. 7 illustrates one specific approach at
optimization computation, it is to be understood that various other
approaches may be suitable. One such alternative approach is illustrated
in FIG. 8. In step 801, data defining the endpoint locations for the
conference and the cost per unit time for calling, in both directions,
from each endpoint to every other endpoint, is retrieved from database
116. As stated previously, cost per unit time (rate) information is
computed by a simple lookup using published tariffs. Note that the rates
selected are those that apply for the time of day at which the conference
is to be initiated.
In step 803, the dollar cost for each location to location pair is
determined, for the expected duration of the call, and the information
stored temporarily, in database 116, in the form of a matrix "B". The
entries in the matrix take the form B ij, representing the cost to call
from location "i" to location "j". In step 805, the lower cost direction
between i and j is determined, in order to construct a second matrix "C",
such that C.sub.ij =min[B.sub.ij,B.sub.ji ].
Next, in step 807, the matrix C is used to represent the edge costs in
order to determine the minimum spanning tree which connects all locations
on the conference call. The resulting tree provides the legs of the
conference call. The originating location for each leg "ij" is determined
from the lower-cost direction between location i and j from step 805. Note
that the solution of a minimum spanning tree problem is a well known and
easily implemented combinational process that may be performed in
processor 112 by suitable programming by persons of ordinary skill in the
art. See, for example, "Combinatorial Optimization: Algorithms and
Complexity," Papadimitriou and Steiglitz, Prentice Hall, 1982. Other
references describe yet other techniques for optimization computation. For
example, see "Routing Techniques Used in Computer Communication Networks",
Schwartz and Stem, IEEE Transactions on Communications, April, 1980; also
"A Note on Two Problems in Connection with Graphs", Dijkstra, Numerical
Mathematics, October, 1959; also "Flows in Networks", Ford and Fulkerson,
Princeton University Press, 1962.
When the optimization processor is operated in accordance with the
invention, calling instructions for each location are generated. For each
location, there is listed the other locations to call, or, if applicable,
which location will call that location. This information may be provided
to the person using the present invention or used to enable processor 112
to formulate and issue to network elements 130, appropriate signaling
instructions to initiate the desired (and now optimized) conference. The
format and handling of signaling messages that initiate and control call
setup and ongoing supervision have been described in many references, and
are accordingly well known to persons skilled in the art.
FIG. 9 is a diagram illustrating the typical format of records stored in
database 116 of FIG. 1. Each record is indexed by originating location,
according to area code and telephone exchange. The record shown in FIG. 9
contains information associated with calls originating from exchange 121
within area code 201. Other records, not shown, contain information for
calls originating from other exchanges and other area codes. For the
particular area code and exchange illustrated in FIG. 9, possible
destinations are all other area codes and all other exchanges in those
area codes. A few possible destination locations are specifically
illustrated in FIG. 9, namely area code 202, exchanges 121 and 999, and
area code 919, exchanges 121 and 999. For each of the destinations shown
in FIG. 9, an individual entry in the record sets forth the cost per unit
time and the discount associated with that type of call. For example, a
call from (201) 121-XXXX to (202) 999-YYYY costs 17 cents per minute, and
a discount of 11% may be applicable under certain conditions. A call from
the same area and exchange to (919) 121-ZZZZ costs 14 cents per minute,
and a discount of 12% applies. The information in each record, although
not shown in FIG. 9, may also describe other applicable factors for calls
made between particular origination and destination locations, such as
overrides, taxes, surcharges, currency exchange information, etc. Also,
the records in database 116 may contain information describing
characteristics and features available in certain customer premises
(terminal) equipment.
FIG. 10 is a diagram illustrating the manner in which a call requesting
conference optimization can be routed to COS 110 from domestic and foreign
locations. If the call originated from location 101 within the United
States, the caller will dial a specific toll free access number in the
format 1-800-NXX-XXXX, where N is a digit between 2-9 and X is any digit
0-9. The call is received by a local exchange carrier (LEC) office 1001
associated with the calling location and recognized (using conventional
equal access screening) as a call to be routed by a particular long
distance carrier, such as AT&T. Accordingly, LEC office 1001 forwards the
dialed 800 number to an AT&T Originating Screening Office (OSO) 1003 along
with a 10 digit billing number (BN) or, if the BN cannot be determined, a
3 digit Originating Numbering Plan Area (ONPA). (The 3 digit code is
commonly called the originating "area code".) The BN or ONPA information
is normally transmitted from LEC office 1001 to OSO 1003 by multi
frequency tones; CCS7 signaling may alternatively be used, if available.
Note that if LEC office 1001 is not equipped for equal access, the
originating NPA code can be derived from either the incoming trunk
subgroup information or from a code transmitted by the LEC in place of the
digits "800".
OSO 1003 retains the 10 digit BN (or 3 digit ONPA) and sends a query to
Inwats Data Base Network Control Point (IDB NCP) 1005 over the signaling
network 1007, using the dialed number and the ONPA, where the customer
record corresponding to the information in the query is retrieved. IDB NCP
1005 returns an Action Point Numbering (APN) number of the form
SSS-TIT-XXXX, where SSS is the switch number of the particular switch
(switch 1011 in FIG. 10) within network 120 to which COS 110 is connected.
TIT is the trunk subgroup for receiving conference setup requests at that
switch, and XXXX is a specific four digit number associated with the
optimization features provided by the present invention.
The call is now routed through various ones of the network elements 1050
within public switched telecommunications network 1060 and delivered to
the appropriate trunk subgroup of switch 1011 corresponding to COS 110.
If the request for conference optimization originated from location 104 in
a foreign country, the caller may dial a direct access number of a
particular long distance carrier, illustratively AT&T, in that country.
The telecommunications administration network 1021 of that country routes
the call to the designated long distance provider with a called party
number of 199-PCC-XXXX, where 199 indicates direct access service and PCC
indicates the country of origin. XXXX may contain information about the
originating station. The call is received by the designated long distance
provider in a switch 1025 such as a #4ESS international switching center
(ISC), which routes the call to a operator service position system (OSPS)
1027, based on the received number. OSPS 1027 stores the 199-PCC-XXXX as
the backward number for the call. When the call is answered at OSPS 1027,
the caller first provides a credit card number (to pay for the direct
access portion of the call). After optional credit card validation, the
caller provides the same dial-in 800 number as was used with respect to a
domestically originated call. OSPS 1027 forwards the dialed 800 number in
standard international call format, namely, in the ISUP called party
number parameter, and places NPA-CCC-XXXX in the charge number parameter,
where NPA is the NPA of OSPS 1027. The call flow continues from here as
was described previously.
Regardless of the location that requested the conference origination, after
COS 110 determines the optimum configuration for the conference,
conference setup may proceed automatically by COS preparing and sending
signaling messages via signaling network 1007 to appropriate network
elements 1050. Alternatively, an operator position may be provided with
information that is then used to connect the locations in the desired and
optimized manner.
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