GB2396078A

GB2396078A - Least cost routing a prepaid telephone call

Info

Publication number: GB2396078A
Application number: GB0404692A
Authority: GB
Inventors: Eli Nhaissi
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-12-02
Filing date: 2000-10-23
Publication date: 2004-06-09
Anticipated expiration: 2020-10-23
Also published as: GB2395863B; GB2395864B; GB2395863A; GB0404688D0; GB2396078B; GB2395862B; GB2395865B; GB2395862A; GB0404685D0; GB0404686D0; GB2395865A; GB2395864A; GB0404687D0; GB0404692D0

Abstract

A method for routing a prepaid telephone call comprising the steps of receiving a telephone call from a customer who has purchased prepaid airtime from a plurality of prepaid carriers; determining which one of said plurality of prepaid carriers is the least-cost prepaid carrier for said telephone call; routing said telephone call to said least-cost carrier; receiving a message from said least-cost prepaid indicating that the prepaid airtime purchased from said least-cost prepaid carrier by said customer is exhausted or nearly exhausted; and re-routing said telephone call to one of said plurality of prepaid carriers other than said least-cost prepaid carrier in response to receipt of said message.

Description

UNIVERSAL EXCHANGE FOR MAKING LEAST

COST NON-LOCAL TELEPHONE CALLS

FIELD OF THE INVENTION

This invention generally relates ' to telephone systems.

In particular, the invention relates to telephone systems for making prepaid or post-paid long-distance and international telephone calico.

BACKGROUND OF THE INVENTION

5 Private telephones located at residences or busi nesses typically are billed on a monthly basis by the local and long-distance carriers. Wireless telephones are also available on the same basis, provided that the' customer is able to meet various standards of credit 10 worthiness. People can also use public telephones by - depositing coins, charging the call to a credit card, or charging the call to a different telephone number using telephone debit cards.

An alternative method of paying for phone calls, 15 which is becoming increasingly prevalent, is to provide prepaying customers with a special code or PIN number which can be used (provided that the prepayment has not been exhausted) at any time to make a phone call. The telephone service is provided by the telephone carrier to 20 whom the prepayment was made. As used herein, the term "prepaid telephone system" means a system in which each prepaying customer is given a unique special code for use in making telephone calls until the prepayment has been exhausted- . 25 A prepaid telephone system and a method for making prepaid telephone calls are disclosed in U.S. Patent No. 4,706,275 issued to Zvi Kamil. The method comprises the steps of: obtaining a special code by making a prepayment; storing the special code and associated prepayment amount

in a memory in a special exchange; connecting to the special exchange when a telephone call connection is desired; transmitting the special code and the number of the called party to the special exchange; verifying that 5 the special code is valid and that the available credit is sufficient to cover the initial cost of the call; .ect.= the al'i.'g party ion co the called party station in response to verification; and disconnecting-the" call when the available credit has been spent. The "special 10 exchange" referred to in U.S. Patent No. 4,706,275 is a telephone switching matrix having an associated computer and memory for performing the special functions of verifying and monitoring prepaid telephone calls. The prepaid customers can connect to the special exchange via 15 either a wire (land) line or a wireless connection. The term "special exchange" will be used in the same sense herein. The method disclosed in U.S. Patent No.64,706,275 has been widely adopted in the telephone industry. Generally, 20 each prepaid carrier has its own special exchange to which its prepaid customers are able to connect. Initially, the prevailing application of the teaching of U.S. Patent No. 4,706,275 was in the context of public telephone connected to a special exchange via a land line. In recent years the 25 teaching of U.S. Patent No. 4,706,275 has been widely adopted by wireless carriers.

In the typical land-line prepaid telephone system, the customer purchases a prepaid telephone card which has a special code, also known as a PIN number, printed on the 30 back of the card. Typically the-PIN number i-s-obscured by a layer of opaque material which is removed after purchase to reveal the secret PIN number to the cardholder. The prepaid telephone card also have one or more access phone numbers printed thereon. At the time of card purchase, the PIN 35 number and prepayment amount (i.e., value of the card

purchased) are recorded by the card issuer and then forwarded to the service provider for storage in computer memory at a special exchange operated by the prepaid telephone service provider. When the customer wishes to 5 make a prepaid telephone call, he/she first dials the access phone number to connect to the special exchange.

Ellen 'are co-lne=ivn is mane, the customer is prompted by a computer to enter the PIN number and the destination phone number. The special exchange then determines whether the 10 call should be connected by verifying that the PIN number is valid and that sufficient prepaid balance is available to cover the cost of the call to the destination phone number If the PIN number is valid and the available balance is sufficient, the call is connected. The running 15 cost of the call is monitored, either by computing the running cost or by calculating the airtime available (based on the charge per minute and the available balance) and then subtracting the call duration from the available airtime. When the available balance/available airtime has 20 been exhausted, the telephone call is disconnected.

The technique for making a prepaid wireless telephone call differs somewhat from the land-line technique. In one type of prepaid cellular (wireless) telephone system, a predetermined amount of airtime may be purchased at the 25 time when the handset is purchased. At the time of the transaction, the purchaser is given a multi-digit Electronic Serial Number (ESN) and a multi-digit purchase identification number (PIN). The ESN, which is imprinted on a plate affixed to the inside of the handset, uniquely 30 identifies that handset. The PIN number merely identifies the particular transaction by which airtime was purchased.

After leaving- the store with the handset and PIN number, the purchaser may call the central office of the wireless carrier to activate the cellular telephone. At that time, 35 the handset purchased by the prepaid customer is assigned a 10-digit telephone number, also known as the Mobile

- - - - a.

i Identification Number (MIN), which uniquely identifies that handset. The activated handset will respond to that MIN and will also transmit that MIN along with the ESN when a call is being made from that handset.

5 The fundamental difference between prepaid and non -Ie-paiu c-eiluiar iciepnone systems is One requirement that the prepaid system only connect the desired call if a certain minimum prepaid credit amount (associated with the particular handset being used) is available. One type of 10 prepaid cellular telephone system employs a prepaid platform comprising a switching matrix, memory for storing MINs and prepaid credit amounts, and a computer (e.g., a central processing unit) for controlling the switches of f-> the switching matrix in dependence on whether a particular 15 MIN of a calling party is valid and whether the required prepaid amount of credit is available, both of which pieces of information are stored in memory and retrieved by the computer of the prepaid platform The prepaid platform for performing the verification 20 and monitoring functions may be situated on the same premises as the wireless carrier's central switching system, hereinafter Immobile telephone switching office" (MTSO), or may be situated away from the MTSO. In either case, the MTSO computer is connected to the prepaid plat f\, 25 form computer via a communications link. For example, the prepaid platform may interface with the MTSO via aT1 communications link. Alternatively, the same computer may perform the functions of both the MTSO and the prepaid platform. In the subsequent description of the functional

30 ity of an exemplary cellular telephone exchange comprising an MTSO and a prepaid platform, it should be understood that the respective functions being described can be performed by a single processor having sufficient computing power, rather than by two processors connected 35 by a communications link.

In one example of a prepaid cellular telephone system, the ESN and MIN are stored in the MTSO's computer memory at the time of handset activation. Also, the MIN and the prepaid amount of airtime/credit are stored in the computer memory of the prepaid platform. When the handset user --i==,es Lo Bake a phone car',.h user endears the destination phone number (including the area code if necessary) he wishes to call and then presses the TALK button. When the TALK button is depressed, the ESN, the MIN 10 and the destination phone number are transmitted by the handset in the form of radiofrequency signals. These radio signals are received by the ' nearest cellular telephone tower, which relays the ESN, MIN and destination phone number to the MTSO, also by transmitting radiofrequency 15 signals. The receiver at the MTSO receives the transmitted signals from the cell tower, which signals carry the ESN, MIN and destination phone number. The computer at the MTSO first matches the ESN to the MIN to ensure against fraud.

This is done by comparing the incoming ESN and MIN with the 20 corresponding pair stored in computer memory at the MTSO.

If the ESN matches the MIN, the MTSO then determines whether the MIN identifies a prepaid customer. If the determination is affirmative, the MTSO computer hands the call off to the prepaid platform via the communications 25 link In response tot-receipt of the MIN and the destination phone number, the computer at the prepaid platform verifies that the MIN is valid and checks the available prepaid credit balance associated with the transmitted MIN to make 30 sure that sufficient credit is available to cover the initial cost of the requested telephone call. These verifications are carried out by comparing the received numbers with the corresponding numbers stored in the prepaid platform memory. If there is sufficient credit 35 available, the prepaid platform computer hands the call back to the MTSO via the communications link. The MTSO

computer then initiates operation of the appropriate switches needed to route the cellular telephone call to the destination phone number. Alternatively, if the prepaid platform has its own telephone switching matrix, the 5 prepaid platform can route the call through its own switches. Upon establishment of a connection between the handset user and the called party, the prepaid platform monitors the call. If the prepaid credit balance is exhausted before 10 the handset user disconnects the call, the prepaid platform initiates disconnection of the call. Then the prepaid platform computer will decrement the available credit balance by the cost of the completed telephone call.

In another type of prepaid cellular telephone system, 15 a cell phone user can prepay for airtime by purchasing a prepaid telephone card from a prepaid carrier different than the wireless carrier from whom the cell phone user has purchased the handset. That prepaid carrier has a special exchange which the cell phone user can access by dialing a 20 special access code, e.g., *999, on his handset. The wireless carrier then forwards the wireless call to the special exchange of the prepaid carrier. Once the connection is made, the cell phone user must input the PIN number which appears on the prepaid telephone card. If the 25 PIN number is valid and if a sufficient amount of prepaid credit is available on that card, the prepaid carrier will route the cell phone user to the station corresponding to the destination telephone number inputted by the user.

Prepaid cellular telephones are ideally suited for 30 persons having a credit rating which falls short of the standard set by a particular wireless carrier as a precondition for purchase of a non-prepaid cellular telephone. One problem, however, is the high cost to the consumer of wireless telephone services and the great 35 variability in the costs charged by different wireless

carriers. The carriers that sell prepaid or postpaid wireless telephone service are the providers of the local, long distance or international service. Once a consumer buys a handset and prepaid or postpaid wireless 5 service from a particular carrier, that carrier is the one that generally provides the network service. To the extent that a consumer believes they are captive to the carrier providing local- wireless service, that wireless carrier is able to charge above-market rates for long 10 distance and international telephone service. Although land-line telephone service is generally cheaper than wireless telephone, land-line telephone service providers also charge at rates which vary widely and which may include hidden charges over and above the simple cost per 15 minute charge.

Today any customer that uses prepaid or postpaid wireless or land-line telephone service can buy prepaid land line usage, a prepaid telephone card, or a prepaid dial tone from any vendor carrier for use with any 20 telephone by dialing a toll-free number or dialing directly to the special exchange of that carrier. In the case of land-line telephones, when the customer is connected to that special exchange, he/she is asked to transmit his/her special code number. In the case of 25 wireless telephones, the wireless telephone transmits its MIN number, which serves the function of a special code or PIN number for verifying an authorized prepaid customer. After the special code and credit available have been verified by the special exchange corresponding, 30 e.g., to the land-line prepaid telephone card being used by the customer, the customer can make long-distance and international telephone calls through that special exchange. Any person has the freedom to select which carrier to 35 purchase prepaid telephone service from. A person may even

purchase multiple prepaid telephone calling cards from multiple prepaid service providers. However, in the latter case, it would be extremely inconvenient and time consuming for each consumer to monitor the telephone rates of differ 5 ent prepaid telephone service providers in order to identify the least-cost provider. This is particularly the case where there is a wide disparity in the methods used to compute telephone charges, Even more -daunting is the fact that each international telephone service provider charges 10 different rates for calls to different countries. The charges for placing a call from the United States to a particular country may vary widely from carrier to carrier.

This is also true of the telephone rates applicable to post-paid longdistance and international telephone 15 service.

Thus there is a need for a method and a system of automatically routing long-distance and international telephone calls to the least-cost carrier in the situation where a consumer is buying long-distance and/or 20 international telephone service from multiple carriers.

This need is especially great in the prepaid wireless telephone market, where the carrier who sells the handset and associated prepaid wireless telephone service to the consumer may charge low rates for local telephone service 25 and high long-distance and/or international rates. Such a prepaid wireless carrier has no incentive to help the consumer to buy long-distance and/or international ser-

vice from its competitors.

SUMMARY OF THE INVENTION

The present invention is a method and an apparatus for 30 enabling a consumer to buy long-distance and/or inter-

national telephone service at the least cost from any one of a multiplicity of alternative carriers. The invention has application in both prepaid and post-paid telephone systems. In addition, the consumer may make the call from

a wireless handset or from telephony equipment connected to a land line. In accordance with the preferred embodi-

ment of the invention, a consumer wishing to make a long-

distance or international call may connect to a universal 5 exchange via a wireless or land-line telephone and then be routed by the universal exchange to the least-cost carrier for that particular call. In the case of wireless telephones, the invention will enable the consumer to buy-

the wireless handset and associated local wireless 1Q prepaid or postpaid telephone service from a wireless carrier, while the consumer will be able to buy non-local telephone service from a least-cost carrier selected from a list of long-distance and/or international carriers with which that particular consumer is doing business. In IS the case of land- line telephones, the invention will enable the consumer to purchase the associated local land-line prepaid or postpaid telephone service, while the consumer will again be able to buy non-local telephone service from a least-cost carrier selected from 20 a list of long-distance and/or international carriers with which that particular consumer is doing business.

The non-local portion of the call can be executed by the longdistance/international carrier through the most competitive means, such as the Internet, telephone line, 25 satellite or microwave communications, optical fibers, television cable, copper wire, etc., or through other wireless carriers.

The invention allows a consumer to avoid excessive telephone cha-rge--andobtain the- mos* economic long 30 distance and/or international telephone service. Here-

tofore, least-cost routing has been used by carriers to decrease their operating costs, but has not been made available to the consumer, In the case of pre-paid cellular telephone service, the invention allows the 35 consumer to buy a handset from a particular wireless carrier and use the same wireless carrier mainly for

f l local wireless calls, while buying long-distance and international telephone service at the lowest possible price, i.e., by buying service on a prepaid or post-paid basis from multiple carriers that compete with each other 5 for the consumer's business. These alternative carriers can be selectively used to make long-distance and/or international calls at rates which are cheaper than those being offered by--the-carrier from which the consumer purchased the handset. Although the consumer during, lo e.g., a long-distance call will be using two telephone services concurrently, i.e., the local carrier and the long-distance carrier, the difference in price between the long-distance rates charged by the local carrier and those charged by the long-distance carrier can be greater IS than the cost of the local wireless service during the long-distance call, resulting in an economic saving to the consumer.

In accordance with the preferred embodiment of the invention, if the consumer needs to make a prepaid non 20 local call, then the consumer will make a phone call to a smart exchange that will be referred to herein as a "universal exchange". This universal exchange, which may be owned by an independent carrier, will be connected to many participating carriers that provide prepaid or post 25 paid telephone service. Each carrier will be identified by the universal exchange with a unique carrier code having, e.g., one to five digits. In accordance with the preferred embodiment of the invention, the universal exchange receives and stores telephone rate information 30 for each participating carrier. In addition, the uni-

versal exchange is programmed with a Ieast-cost routing function which uses the stored telephone rate information to calculate the cost of a call for each available carrier and then identify the least-cost carrier for that 35 call. Based on that determination, the universal exchange

then routes the call to the exchange of that least-cost carrier. For each customer of the universal exchange, the pool of available carriers will include those carriers -I p=-t_cit ng with the u..iYersa' exchange and Am which the customer has purchased prepaid long-distance or international telephone service, e.g., prepaid telephone calling cards, and those participating long-distance/ international carriers which the customers has accounts lo with. For each participating carrier, the universal exchange will assign a unique carrier code. The universal exchange will also assign a special identification code to each of its customers. In response to messaged requests from the universal exchange computer during an 15 initialization procedure, the customer will provide the carrier codes for the multiple prepaid telephone calling cards and for the multiple telephone accounts held by that customer. This set of carrier codes received by the universal exchange must be associated with the customer 20 identification code of that customer in the universal exchange memory. In the case of a customer who owns a wireless handset, the customer identification code recog nized by the universal exchange can be the MIN for that particular handset. In the case of a customer who intends 25 to make calls to the universal exchange from a residen tial or business telephone, the customer identification code recognized by the universal exchange can be the number for the telephone line to which that telephone is connected. In both of the foregoing cases, the universal 30 exchange can utilize known "caller ID" technology to recognize the calling telephone number. Alternatively, the customer may select or be assigned a unique customer identification code different than his/her telephone number. In the case where the customer uses prepaid 35 telephone calling cards only, the universal exchange customer may remain anonymous, being identified to the

to the universal exchange by nothing more than a code or password. After initialization, the universal exchange is ready to process any telephone call from the customer.

F-L- P=F- caviar eiepnone call, the universal exchange needs to receive only the customer identification code of the customer and the destination phone number. Based on the prestored list of carriers for which that particular customer is holding prepaid calling cards or has accounts 10 and the associated rate schedules and based on the destination of the telephone call, the universal exchange identifies and routes the call to the exchange of the least-cost carrier. That exchange then processes the call. In the case of a pre-paid least-cost carrier, the 15 exchange to which the call is routed will be a special exchange. In the case of a post-paid least-cost carrier, the exchange to which the call is routed will be a regular exchange. In addition to be able to connect to any participating carrier, it must be appreciated that 20 once a customer has a subscription or account with the universal exchange, the customer can access the universal exchange from any telephoning means via any known telecommunications channel, whether it be a land-based telephone line or a wireless communications link.

25 In accordance with one preferred embodiment, if the least-cost carrier is a prepaid carrier, the special exchange of that least-cost prepaid carrier interacts directly with the customer once the call has been routed ... by the universal exchange. For example, before the call 30 is routed by the special exchange of the least-cost prepaid carrier, that special exchange will ask the customer to enter his PIN number. Then the special exchange will verify that prepaid credit corresponding to that PIN number is available. If the PIN number is valid 35 and sufficient prepaid credit is available, the special

exchange of the least-cost prepaid carrier will route the call to the station identified by the destination telephone number. On the other hand, if the least-cost carrier is a post-paid carrier, then the universal 5 exchange routes the call to the regular exchange of that least-cost postpaid carrier, who will bill the customer's account accordingly.

In accordance with another preferred embodiment, the PIN numbers corresponding to the carrier codes of prepaid 10 carriers are communicated to the universal exchange by the customer during the initialization procedure. These PIN numbers are stored with the corresponding carrier codes in memory at the universal exchange. Each PIN number identifies a respective prepayment transaction in 15 which the customer has purchased future telephone service to be provided by a respective one of a plurality of prepaid carriers. After the universal exchange performs its least-cost routing routine and if a least-cost prepaid carrier has been identified, the universal 20 exchange routes the call to the special exchange corresponding to the least-cost prepaid carrier, along with the corresponding PIN number. Then the special exchange of the least-cost prepaid carrier verifies the PIN number and associated available prepaid credit, and 25 routes the call to the station identified by the destination telephone number This embodiment has the advantage that the customer is relieved of the inconvenience of inputting the- PIN number for each telephone call, but rather need input the PIN number only 30 once, namely, during the initialization procedure.

A further preferred embodiment comprises a system-

and a method for routing a prepaid telephone call comprising the steps of: receiving a telephone- call from a customer who has purchased prepaid airtime from a plurality 35 of prepaid carriers; determining which prepaid carrier is

the least-cost prepaid carrier for -that telephone call; routing the telephone call to that least-cost prepaid carrier; receiving a message from the least-cost prepaid carrier indicating that the prepaid airtime purchased from 5 that carrier by that customer is exhausted or nearly exhausted; and re-routing the telephone call to one of the other prepaid carriers, e.g., -the second-lowest-cost prepaid carrier, in response to receipt of the message.

In accordance with an alternative preferred embodi-

10 meet, the verification and monitoring functions performed by special exchnages may be performed by the universal exchange, which acts as a service bureau for the prepaid carriers. In this case, the customer must also input, e.g., via the telephone keypad, the PIN numbers during 15 initialization. In addition, the PIN number and prepayment amount for each calling card must be received from all prepaid carriers served by the universal exchange. That information is stored in memory along with the corresponding carrier codes. If the universal 20 exchange identifies a least-cost carrier from amongst the available prepaid carriers listed in memory for a particular customer, the universal exchange then uses the PIN number for the selected carrier, which PIN number was previously inputted by the customer, and matches that PIN 25 number with a corresponding PIN number in the table of prepayment amounts. The universal exchange then verifies the available prepaid credit amount corresponding to the PIN number of the selected carrier, i.e., the least- cost routing routine excludes as least-cost carrier any carrier 30 for which the- available balance is insufficient to cover the initial cost of the telephone call to the station identified by the de-ctinatin telephone n,.e'. I, the customer has sufficient available prepaid credit with the selected least-cost carrier, the universal exchange routes 35 the call to that least-cost carrier. Once the customer is connected to the station identified by the destination

telephone number, the universal exchange can monitor the ongoing telephone call.

The foregoing method and system will enable the consumer to call any place in the world at the cheapest 5 rate using least-cost routing amongst the different non-

o a'''== yaYuBipa-ihq widen the universal exchange and with which the customer has an account (in the case of post-paid telephone service) or a prepaid balance (in the case of prepaid telephone service).

10 In accordance with a further alternative preferred embodiment, the universal exchange monitors the quality of the connection made by the least-cost carrier. If the connection is unsatisfactory, e.g., because of diminished signal strength or excessive interference, the universal 15 exchange can automatically re-route the call to the second-lowest-cost carrier.

In addition, the universal exchange enables a consumer to use one telephone line to connect to multiple parties for making a conference call. The universal 20 exchange accomplishes this by routing calls to two or more conference participants via respective exchanges of carriers which the consumer is doing business with (prepaid or post-paid). Optionally, if the consumer has multiple prepaid PIN numbers with one carrier, the 25 universal exchange can connect multiple parties for a conference call via multiple lines to the special exchange of that carrier. This can be accomplished using known conference-call switching technology in theuniversal exchang-e-.

BRIEF DESCRIPTION OF THE DRAWING

30 FIG. 1 is- a block diagram showing- a telephone system having a universal exchange in accordance with the pre-

erred embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiment of the invention will be described with reference to FIG. 1. In FIG. 1, the universal exchange is represented by the block designated by reference numeral 2. The basic cQmnnnents Of Ohm 5 universal exchange 2 include a telephone switching matrix 4 for routing telephone calls; a computer 6 for processing incoming telephone calls in accordance with a computer program stored in computer memory and sending À control signals to the telephone switching matrix 4 for 10 routing an incoming telephone call to the exchange of a preferred telephone carrier (prepaid or post-paid); and memory 8 for storing customer identification codes, a respective list of telephone carrier codes corresponding to each customer identification code, and a respective 15 rate schedule corresponding to each telephone carrier code. It will be readily appreciated that some or-all of memory 8 may be integrated into the computer 6.

The universal exchange 2 receives and distributes telephone calls via a public telephone system 10 The 20 universal exchange can receive telephone calls from customers who use a wireless handset, a land-line telephone, a computer connected to the Internet, or any other type of telephoning apparatus. FIG. 1 shows a wireless handset 12 which can communicate with the 25 universal exchange via a cell tower 14, a wireless local exchange 16 (prepaid and/or post-paid) and the public telephone system 10; a land-line telephone 18 which can communicate with the universal exchange via a land-line local exchange 20 and the public- telephone system 10; and 30 a personal computer 30 which can communicate with the universal exchange via a telephone exchange 32 of an Internet service provider and the public telephone system TO Regardless of the telephoning means used by the customer, the customer accesses the universal exchange by

L;..........

_ n inputting or dialing an access telephone number of the universal exchange. The access telephone number of the universal exchange will appear on the prepaid calling cards of prepaid carriers participating with the univer 5 sal exchange. If the local service is prepaid, then the local exchange 16 will preferably be a special exchange of the type disclosed in U.S. Patent No. 4,706,275...DTD: In accordance with the preferred embodiment of the invention, the universal exchange 2 routes each incoming 10 prepaid telephone call to the exchange of a preferred (e.g., least-cost) carrier, also via the public telephone id. system 10. Alternatively, the universal exchange could be -' connected to a particular exchange via dedicated tele phone lines. For the purpose of illustration, FIG. 1 15 shows three exchanges 22, 24 and 26 operated by or on behalf of respective telephone carriers X, Y and Z. For the purpose of this example, exchanges 22 and 26 are special exchanges of the type disclosed in U.S. Patent No. 4,706,275 and carriers X and Z are prepaid carriers, 20 while exchange 24 is a regular exchange of a post-paid carrier Y. Each special exchange comprises a telephone switching matrix for routing incoming telephone calls, a computer for verifying and monitoring incoming telephone calls in the manner described in U.S. Patent No. 25 4,706,275, and a memory for storing PIN numbers (i.e., special codes) and the respective amounts of prepaid credit associated with each PIN number. The regular exchange may be any known post-paid telephone exchange comprising a telephone switching matrix and suitable 30 control means for routing calls through that matrix.

In accordance with a further aspect of the preferred embodiment, the universal exchange 2 interrogates each exchange 22, 24- and 26 and receives rate schedule information for each of carriers X, Y and Z via respec 35 tive dedicated data lines 28. Preferably the universal

exchange performs the interrogations at regular inter-

vals, e.g. r daily. Alternatively, the universal exchange may have an arrangement with a particular carrier that the latter will immediately advise the universal exchange 5 (via a data line) of any changes in that carrier's rate schedule. Regardless of the protocol mused to cocci== the rate schedule information, the universal exchange stores that information in memory 8 for subsequent use by the computer 6 determining the leastcost carrier. The person 10 skilled in the art of voice and data communications will readily appreciate that data can be transmitted from the respective exchanges 22, 24 and 26 to the universal exchange 2 via the public telephone system 10.

In accordance with one aspect of the invention, 15 customers can own multiple prepaid telephone calling cards purchased from multiple prepaid telephone carriers; can open multiple accounts with multiple post-paid telephone carriers; or can utilize a mixture of prepaid telephone calling cards and post-paid telephone accounts 20 when making calls through the universal exchange. In this situation, it is desirable, when making a telephone call to a desired destination, to employ the telephone services of the carrier which will charge the least amount of money for that telephone call. It would be 25 inconvenient and time-consuming for the telephone customer to make inquiries with each available carrier to investigate and compare telephone rate schedules to find the respective rates applicable for a call to a desired destination at a particular time of day. [As used herein, 30 the term- "available carriers" means the pool of carriers for which the customer either holds prepaid calling cards or has opened telephone service accounts. The preferred embodiment of the invention envisions that the least-cost carrier in the carrier pool for that customer will be 35 automatically determined by a universal exchange. The universal exchange comprises a computer programmed to

route each incoming call to the least-cost available carrier, whether prepaid or post-paid.

In accordance with the preferred embodiment of the invention, any party wishing to use the low-cost routing 5 service provided by the universal exchange must participate in an initialization procedure. Preferably, the initialization procedure is carried out by means of a ..... telephone connection between the party wishing to become a customer and the computer or a dedicated processor at 10 the universal exchange. The information gathered during initialization is automatically loaded into memory at the universal exchange. Alternatively, the party wishing to become a customer may interact with a service repre-

sentative of the universal exchange via a telephone 15 connection or in person. If the universal exchange charges calling parties for its leastcost routing service, then arrangements must be made for payment by the new customer. For example, the universal exchange may open up a new account with the new customer, with bills 20 to be sent to that customer periodically after the service is provided. Alternatively, the universal ex-

change may require a prepayment, e.g., by means of a charge to a credit card or debit card. Alternatively, the universal exchange may be paid by the carriers. The 25 present invention is not limited to any particular method by which the universal exchange receives payment.

Regardless of whether the new customer receives prompts from _a computer or a _service representative during the initialization procedure, the new customer 30 must provide a means (e.g., a password or user name or special code) by which the universal exchange can identify that customer. The new customer must also identify all of the participating prepaid carriers from which that customer has purchased or will purchase pre 35 paid calling cards and all of the participating carriers

with which that customer has opened post-paid accounts for long-distance or international telephone service. The universal exchange will assign a unique customer identi-

fication number -to that customer, e.g., in the case of 5 wireless telephones, the MIN can be used as the customer identification number. Preferably, each carrier will be identified by a preassigned carrier code (consisting of one or more digits). In the case of prepaid carriers, the preassigned carrier code may appear on the prepaid call lO ing cards sold by or on behalf of that carrier, so that the customer can simply input the carrier code to the universal exchange via a telephone connection. To complete the initialization process, the universal exchange preferably stores a data table in memory 8 (see 15 FIG. 1) which is addressed by the customer identification number and which contains a list of carrier codes for all of the carriers which are available to the identified customer and have been inputted to the universal exchange by that customer.

20 In accordance with the preferred embodiment of the invention, the universal exchange is programmed to perform a least-cost routing function for each incoming - call from its customers. The algorithm for performing the least-cost routing function comprises the following 25 steps. First, the universal exchange stores the customer identification code and the destination phone number of the incoming call in registers. The computer 6 then retrieves a list of the carrier codes associated with the inputted Customer identification code from a data table 30 in memory 8. For the sake of this example, it will be assumed that the calling customer holds prepaid calling cards purchased from carriers X and having special exchanges 22 and 26, respectively, and has opened a telephone service account with a long-distance/inter 35 national carrier Y having a regular exchange 24. Then the computer 6 retrieves the rate schedule information for Q

the carrier identified by the first carrier code (assume carrier X is listed first) on the list. Preferably the rate schedule information is stored in internal memory of the computer 6. Alternatively, the rate schedule 5 information can be stored in memory 8 Based on the destination indicated by the registered destination phone number and on the rate schedule information for the prepaid carrier-X,-the computer calculates the cost of a call having a predetermined duration (e.g, 1 minute), 10 assuming that the call were routed through carrier X. The calculated cost for carrier X is stored in a "least-cost" register, while the carrier code for carrier X is stored in a "least-cost provider" register. The computer 6 then calculates the cost of a call having the same 15 predetermined duration, assuming that the call were routed through post- paid carrier Y and using the rate schedule information for carrier Y. The resulting calculated cost for carrier Y is compared to the calculated cost stored in the ''least cost" register. If 20 the calculated cost for carrier Y is less than the value retrieved from the "least cost" register, then the calculated cost for carrier Y is stored in the "least cost" register in place of the calculated cost for carrier X. In addition, the carrier code for carrier Y is 25 stored in the "least-cost provider' register in place of the carrier code for carrier X. If the calculated cost for carrier Y is greater than the value retrieved from the 'ileast cost" register, then the computer proceeds to calculate the cost of a call having the same predeter . 30 mined duration, assuming that the call were routed through prepaid carrier Z and using the rate schedule information for carrier Z. The resulting calculated cost for carrier- Z is compared to the calculated cost stored in the "least cost" register. If the calculated cost for 35 carrier Z is less than the value retrieved from the "least cost" register, then the calculated cost for carrier Z is stored in the "least- cost" register in place

\ of the current value stored therein. In addition, the carrier code for carrier Z is stored in the "least-cost provider" register in place of the current carrier code stored therein. If the calculated cost for carrier Z is 5 greater than the value retrieved from the "least cost" register, then the computer would repeat the iteration for each additional available carrier until all had been processed. At the end of the foregoing least-cost routing -

routine, the carrier code currently stored in the "least 10 cost provider" register will be that carrier determined to be the least-cost provider of the telephone service in question, i.e., the call being placed by the customer to the destination phone number. The computer 6 then sends-

the appropriate control signals to the telephone 15 switching matrix 4 for routing the call to the exchange of that least-cost carrier.

Preferably the next carrier to be processed by the least-cost routing algorithm is selected at random from the pool of available carriers. If it is determined that 20 the calculated cost for the next carrier is equal to the current least cost stored in the "least cost" register, the carrier code for that next carrier is not substituted for the carrier code stored in the "least-cost provider" register. The random selection of carriers for processing 25 will provide that the least-cost carrier will be selected from a group of equal-cost carriers at random. Any other technique for randomly selecting a least-cost carrier from a group of equal-cost carriers can be used.

In accordance with the preferred embodiment of the 30 invention, each prepaid carrier, once it receives a routed call from the universal exchange, verifies and monitors the incoming call in accordance with the teaching of U.S Patent No. 4,706,275. When the amount of credit available to the prepaid customer has been 35 exhausted, the special exchange of the prepaid carrier

JO may either disconnect the call or return the call to the universal exchange. In the latter case, the special exchange sends a warning message to the universal exchange a predetermined amount of time (e.g., 10 5 seconds) prior to disconnection of the call by the special exchange. In response to the warning message, the universal exchange re-runs the least-cost routing algorithm for the same set of carriers, except that the least-cost prepaid carrier is excluded, and uses that 1Q algorithm to determine the second-lowest-cost carrier (prepaid or post-paid). The universal exchange then re-

routes the call to the second-lowest-cost carrier. A call can also be rerouted to the second-lowest-cost carrier-

if the access lines to the exchange of the least-cost 15 carrier are busy. If the second-lowest-cost carrier is a prepaid carrier, then when the available prepaid credit with the second-lowest-cost carrier is exhausted, the foregoing steps can be repeated to re-route the telephone call to a third-lowest-cost carrier and so forth. The 20 universal exchange is preferably equipped with a telephone switching system which is capable of re-routing the telephone call from one carrier to another without interrupting the connection between the calling and called parties. However, if the universal exchange has a 25 telephone switching system without the foregoing capability, then the special exchange of the leastcost prepaid carrier can interpose a first recorded message stating that the caller has a predetermined amount of time (e.g., one minute) remaining before the call will be 30 interrupted. After the first message and before interruption of the call, the special exchange of the least- cost prepaid carrier can interpose a second recorded message asking the calling party to speak a - predetermined word, e.g., "just", if he/she wants the 35 call to be re-routed through another carrier. If the calling party speaks the predetermined word, a voice recognition module at the special exchange recognizes

4. an. -

-- L _ -.iE that word and initiates a further recorded message instructing the called party to hang up and await a re-

call. At the same time, the universal exchange is notified that the telephone call needs to be re-routed.

5 When the prepaid airtime is exhausted, the special exchange of the least-cost prepaid carrier returns the call to the universal exchange and the latter then re-

routes the call to the second-lowest-cost carrier. Thus the consumer can continue the telephone call without the 10 need to recharge his available balance.

In a further preferred embodiment, after the calling party has been connected to the called party by the least-cost carrier, the universal exchange monitors the quality of the connection, e.g., using packet switching 15 or other technology. If the signal is too weak or the noise is too great, the universal exchange can 'auto-

matically re-route the call to the second-lowest-cost carrier or any other carrier irrespective of cost.

In accordance with another preferred embodiment, the 20 PIN numbers corresponding to the prepaid carrier codes are communicated by the customer during the initializ-

ation procedure. These PIN numbers are stored with the corresponding carrier codes in memory 8 at the universal exchange 2. After the universal exchange performs its ! 25 least-cost routing routine and a least-cost prepaid "'!'''2t carrier has been identified, the universal exchange routes the call to the special exchange corresponding to the least-cost prepaid carrier, along with the corresponding PIN number. Then the special exchange of 30 the least-cost carrier verifies the PIN- number-- a-nd-

associated available prepaid credit, and routes the call to the station identified by the destination telephone number. Thus the customer need not interact with the special exchange directly, but rather may make a least 35 cost phone call by simply accessing the universal

exchange and inputting his/her customer identification number and the destination telephone number.

In accordance with an alternative preferred embodiment, the verification and monitoring functions of 5 any special exchange may be performed by the universal exchange, which acts as a service bureau for that prepaid carrier. In this case, the customer must also input during initialization the PIN numbers for each prepaid carrier for which the universal exchange is acting as a 10 service bureau. In addition, the PIN number and prepay-

ment amount for each calling card must be received from each prepaid carrier being- served by the universal exchange. For example, the universal exchange 2 may-

interrogate each special exchange 22 and 26 and receive 15 PIN numbers and associated prepayments for each of carriers X and Z via respective dedicated data lines 28.

Preferably the universal exchange performs the interroga-

tions at regular intervals, e.g., hourly or daily.

Alternatively, the universal exchange may have an 20 arrangement with a particular prepaid carrier that the latter will advise the universal exchange (via a data line) of the PIN number and prepayment amount for each purchased calling promptly after each transaction. That information is stored in memory along with the 25 corresponding carrier codes. In particular, the computer 6 of the universal exchange may construct a database consisting of customer identification codes, the carrier codes associated with each customer identification code, the PIN numbers associated with each carrier code, and 30 the available prepaid balance associated with each PIN number. This database is stored in memory 8. The computer 6 is preferably programmed with a database manager which amends and updates the database on a continuous basis. As part of the database construction process, preferably the 35 computer 6 also verifies that the PIN numbers inputted by the customer for each prepaid carrier are valid, e g., by

matching each PIN number inputted by the customer with a corresponding PIN number provided to the universal exchange by the prepaid carrier.

After the universal exchange 2 identifies a least 5 cost prepaid carrier from amongst the available carriers (prepaid or post-paid) listed in memory 8 for a particular customer, the universal exchange verifies the available prepayment amount corresponding to the PIN number of the selected prepaid carrier, i.e., the least 10 cost routing routine excludes as least-cost carrier any carrier for which the available balance is insufficient to cover the initial cost of the telephone call to the station identified by the destination telephone number If the customer has sufficient available prepaid credit with the 15 selected least-cost prepaid carrier, the universal exchange routes the call to that least-cost prepaid carrier. Once the customer is connected to the station identified by the destination telephone number, the universal exchange can monitor the ongoing telephone call and open the 20 connection when the prepaid balance has been exhausted or fallen below a predetermined threshold.

The foregoing system and method of processing tele-

phone calls will enable the consumer to call any place in the world at the cheapest rate using least-cost routing 25 amongst the different carriers participating with the universal exchange for which each customer holds prepaid telephone calling cards or has opened post-paid accounts for long-distance/international service.

In accordance with an alternative preferred embodi 30 meet, known teleconferencing switching equipment can be installed at the universal exchange to enable consumers to use one telephone line to connect multiple parties to make a conference call. The consumer would access the universal exchange and then enter a special code 35 indicating that the customer wishes to make a conference

f call. That call is then automatically directed to the teleconferencing switching system, which directs the customer to enter the telephone number of each conference participant. Each participant is called separately and 5 then connected into the conference call or placed on held to be connected later. The universal exchange refits= each.

call to each participant through a different exchange which the calling party has an post-paid account or a prepaid balance. All of the called participants are 10 bridged by the teleconferencing switching equipment at the universal exchange to create the conference call.

Alternatively, if the customer has multiple PIN numbers with one special exchange, the universal exchange could route multiple calls to multiple participants through 15 that one special exchange, using a different PIN number for each call to a different participant. Similarly, if the customer had multiple post-paid accounts with a single carrier, multiple calls to conference participants could be routed through a single carrier.

20 While the invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, 25 many modifications may be made to adapt a particular situation to the teachings of the invention without departing from the essential scope thereof. Therefore it is intended that the invention not be limited to the particular embodiment disclosed as the best mode -3-0contemplatedfor carrying out this-invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

CLAIMS:

1. A method for routing a prepaid telephone call comprising the steps of: receiving a telephone call from a customer who has purchased prepaid airtime from a plurality of prepaid carriers; determining which one of said plurality of prepaid carriers is the least-cost prepaid carrier for said telephone call; routing said telephone call to said least-cost prepaid carrier; receiving a message from said least-cost prepaid carrier indicating that the prepaid airtime purchased from said least-cost prepaid carrier by said customer is exhausted or nearly exhausted; and re- routing said telephone call to one of said plurality of prepaid carriers other than said least-cost prepaid carrier in response to receipt of said message.

2. The method as recited in claim 1, further comprising the step of determining which one of said plurality of prepaid carriers is the secondlowest-cost prepaid carrier for said telephone call, wherein said telephone call is re-routed to said second-lowest-cost carrier.

3. A system for routing a prepaid telephone call comprising: an access line for receiving a telephone call from a customer who has purchased prepaid airtime from a plurality of prepaid carriers; means for determining which one of said plurality of prepaid carriers is the leastcost prepaid carrier for said telephone call; means for routing said telephone call to said least-cost prepaid carrier; a communications channel for receiving a message from said least-cost prepaid carrier indicating that the prepaid airtime purchased from said least-cost prepaid carrier by said customer is exhausted or nearly exhausted;. and means for re-routing said telephone call to one of said plurality of prepaid carriers other than said least-cost prepaid carrier in response to receipt of said message.

4. The system as recited in claim 1, further comprising means for determining which one of said plurality of prepaid carriers is the second-lowest-cost prepaid carrier

for said telephone call, wherein said telephone call is re-routed to said second lowest-cost carrier by said re-routing means.