Telecommunications – Radiotelephone system – Usage measurement
Reexamination Certificate
1999-12-23
2004-01-20
Chin, Vivian (Department: 2682)
Telecommunications
Radiotelephone system
Usage measurement
C455S407000, C455S408000, C455S410000, C379S144020
Reexamination Certificate
active
06681105
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to telephony by means of mobile terminals and a network operating infrastructure which is generally fixed but which could also include relaying via satellites in low orbit. A particularly important, although non-exclusive application of the invention lies in digital telephony.
Existing systems for digital cellular telephony, such as GSM and DECT 1800, comprise a network of base stations capable of communicating with one another and with mobile terminals, and the structure of such a network is complex for reasons of confidentiality, of international use, and of transmission security. Such systems require a potential user to deal with a limited number of points of sale and to take out a subscription that binds the user for a period of time that is generally long and that comes to an end only on deliberate termination. These constraints dissuade many people who need a mobile telephone only for very short periods of time, during which it is unusual for them to occupy locations that are very far apart from one another. The same drawback exists for other cellular networks and remains even when implementing the UMTS standard.
The sale of smart cards for inserting into a standardized terminal and containing a fixed number of prepaid telephone charging units provides a solution that is effective in part only, since the user must still have available a standard terminal that is complex. In addition, the introduction of such cards has increased the number of thefts of terminals.
Discardable cellular telephones are also known (WO-A-96/03001).
SUMMARY OF THE INVENTION
The invention seeks essentially to provide a method and a system for mobile radio telephony that gives immediate access to the network on purchase of a terminal, that is of low cost, and that allows telephone calls to be made during a limited length of time only, while being comparable in convenience to a complex cellular telephone, and without requiring a public telephone to be found.
To this end, the invention proposes in particular a radio telephony method implementing a network having at least one call center and portable terminals each given a predetermined credit of telephone charging units and each having fixed means for calling a single center, in which method, on the first occasion a call is made from a terminal, the terminal transmits an identifier to the single call center and the call center transmits a temporary subscriber number to the terminal, thereby enabling said terminal to be called via the network, and said number is stored in the call center.
On each call from the terminal, the debit is incremented and is compared with the credit, or is debited from the credit. When credit has been exhausted, calls from the terminal are rejected and/or the terminal is invalidated, and its subscriber number is released, possibly after a period of time.
The invention also proposes a digital radio telephony system comprising a network having at least one call center and having portable terminals each of which stores identity data, a call number for a single center belonging to the network, and optionally an indication of an initial number of units that can be transmitted to the center.
Finally, the invention proposes a terminal that is usable in a system of the kind defined above, the terminal including a speech encoder/decoder connected to means for transmitting/receiving a carrier that is modulated by a speech signal, a preprogrammed memory that is not accessible for writing and that is protected for reading, the memory containing an identifier, means for making a call to a single call center having a predefined number that is stored, and for transmitting the identifier, optionally together with prerecorded credit, transmission being in secure form. It is nevertheless more convenient for the credit to be deduced by the network from the identifier that it receives. The identifier should comply with the standards of the radio network used, e.g. the 11 to 15 digit standard presently provided in GSM.
To reduce the cost of the terminal, it is possible to provide it with a single call button causing a link to be established with the call center by ‘dialling’ the number of the center, assuming that only outgoing calls are authorized. Nevertheless, it is preferable to provide one or more buttons enabling the terminal to be switched off, to be put on standby (to receive calls), to answer an incoming call, and to seize a line to make an outgoing call.
The screen usually provided on cellphones can be omitted, thereby also reducing cost. However a monochrome or a color liquid crystal screen can be maintained for the purpose of displaying prerecorded messages that are stationary or animated, including advertising messages or games, so as to create a collectible. However the screen is not intended to display telephone information.
The invention has numerous applications since various circumstances make it essential to have a mobile telephone even though a subscription is not otherwise justified or when the conditions required for obtaining a subscription are not satisfied (e.g. people away from home).
By way of non-limiting example, mention can be made of children on an occasional trip, in particular during school holidays, people having a bad credit rating, and managers working away from the office under circumstances where there is reason to fear that a conventional mobile telephone will break down, be stolen, be lost, or be forgotten.
The terminals can be sold in supermarkets or in tobacconists, for a prepaid amount which may be accompanied by the constraint of telephoning only from or only to the country of sale. To reduce the cost price of the terminal, its case may carry advertising with a contribution to costs coming from the advertiser.
The telephone number allocated to the purchaser is kept valid so long as a credit balance remains and/or so long as a term of validity has not expired, and it enables the purchaser to be called, including from abroad, via the network with which the telephone is associated. The terminal is generally not rechargeable so as to avoid risks of fraud.
The operating principle can implement means comparable to those used for phone cards and for GSM, but in highly simplified form, particularly in the most common circumstance of no recharging being provided for. Nevertheless, and this is an essential difference, the prepaid amount is debited by the network on the basis of the credit communicated by the call center. Terminals are invalidated after their credit has been used up and/or after their period of validity has expired, but they may optionally be collected so that various components thereof can be reused several times over, e.g. the vocoder and the high frequency head (as happens with so-called discardable cameras). Management at the call center and at the charging center is very simple and very flexible. The initial credit can be decremented progressively with the caller being informed of the balance by the call center each time a new call is made. Consumption can be determined as use takes place and compared with the initial credit. The option of receiving calls can be maintained by programming at the call center for a determined duration after credit has expired, possibly accompanied by a message indicating that credit has expired.
The initial operations of putting into service by allocating a number, and then of establishing a call can be performed by means of a voice server. Nevertheless, it is not always justifiable, these days, to make use of human operators.
The identifier can be implemented in a manner comparable with that used in GSM and can be calculated on the basis of a serial number, a manufacturer's number, etc. which numbers are inaccessible from the outside and are calculated by means of an algorithm such as the data encryption standard (DES), or the Rivest Shamir Adleman (RSA) algorithm, or an algorithm requiring zero knowledge input.
To simplify the terminal, it is preferable to avoid data transfer other than transfer of data
Chin Vivian
France Telecom
Larson & Taylor PLC
Milord Marceau
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