Telephonic communications – With usage measurement
Reexamination Certificate
1999-12-02
2002-04-30
Tieu, Binh (Department: 2643)
Telephonic communications
With usage measurement
C379S114020, C379S114260, C379S115020, C379S115030, C379S127030, C379S202010, C379S221010
Reexamination Certificate
active
06381315
ABSTRACT:
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 calls.
BACKGROUND OF THE INVENTION
Private telephones located at residences or businesses 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-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, 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 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.
A prepaid telephone system and a method for making prepaid telephone calls are disclosed in U.S. Pat. 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 the special code is valid and that the available credit is sufficient to cover the initial cost of the call; connecting the calling party station to the called party station in response to verification; and disconnecting the call when the available credit has been spent. The “special exchange” referred to in U.S. Pat. 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 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. Pat. No. 4,706,275 has been widely adopted in the telephone industry. Generally, 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. Pat. No. 4,706,275 was in the context of public telephone connected to a special exchange via a land line. In recent years the teaching of U.S. Pat. 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 back of the card. Typically the PIN number is 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 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 make a prepaid telephone call, he/she first dials the access phone number to connect to the special exchange. When the connection is made, the customer is prompted by a computer to enter the PIN number and the destination phone number. The special exchange then determines whether the 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 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 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 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 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, the handset purchased by the pre-paid customer is assigned a 10-digit telephone number, also known as the Mobile 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.
The fundamental difference between prepaid and non-prepaid cellular telephone systems is the 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 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 the switching matrix in dependence on whether a particular 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 and monitoring functions may be situated on the same premises as the wireless carrier's central switching system, hereinafter “mobile telephone switching office” (MTSO), or may be situated away from the MTSO. In either case, the MTSO computer is connected to the prepaid platform computer via a communications link. For example, the prepaid platform may interface with the MTSO via a T
1
communications link. Alternatively, the same computer may perform the functions of both the MTSO and the prepaid platform. In the subsequent description of the functionality 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 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 wishes to make a phone call, the user enters 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 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 transm
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