BACKGROUND TO THE INVENTION South Africa has approximately 126000 registered taxis which convey 3.5 million commuters on a daily basis. Many of these commuters live in areas that have poor telecommunications infrastructure. Applicant believes that the needs of such commuters can be met by means of a telephone communication system which is available for use in the taxi in which they are travelling.

BRIEF DESCRIPTION OF THE INVENTION According to the present invention there is provided a telecommunication system which comprises a cellular telephone, timing means, control means for entering a selected period of purchased call time during which said cellular telephone can be used, means for starting the timing means, and means for disabling said cellular telephone at the end of said selected period.

Said telecommunication system can include an array of lights, said control means illuminating all or a selection of said array of lights in dependance on the amount of call time purchased.

Said telecommunication system can include a cradle for the cellular phone and a control unit including said control means, said array of lights and said timing means, said cradle having an array of lights which corresponds to the array of lights of the control unit, and there being means for ensuring that the lights which, in use, are illuminated on the cradle replicate the lights illuminated on the control unit.

Each array of lights can include a number of lights of a first colour and a single light of a different colour.

In the preferred form said means for starting the timing means generates a start signal upon a called number answering.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawing in which:- Figure 1 is a diagrammatic representation of a telecommunication system in accordance with the present invention ; and Figure 2 is a block diagram.

DETAILED DESCRIPTION OF THE INVENTION In Figure 1 reference numeral 10 designates a cellular telephone.

Such a telephone is referred to as a"mobile"in European countries and the USA.

The cellular telephone will in this description be referred to as a cell phone.

A cradle 12 is provided for receiving the cell phone 10, the cradle 12 and cell phone 10 being connected by a communication and power cable 14.

The third component of the system is a unit 16 which is for the driver's use. The unit 16 and cradle 12 are connected by a communication and power cable 18.

The main power supply is constituted by a direct current power source (not shown) connected to the unit 16 by way of a power cable 20.

The cell phone 10 is standard except in one respect. This is that a signal is generated and is available at an external data port immediately a call made from the cell phone connects to the called number. The cell phone's keypad and display are used in conventional manner to initiate and terminate calls.

The cradle 12 provides a pocket for receiving the cell phone 10. The cradle does not include any electronics but does include a series of lights (preferably LEDs) which indicate the available call time. In the illustrated embodiment there is a red light 22 and four green lights 24,26, 28, 30. If only the red light 22 is illuminated, this indicates that less than a minute of purchased call time remains available. When the red light 22 and the green light 24 are illuminated, the caller has between one and two minutes left. When the red light 22 and the two green lights 24,26 are illuminated there is between two and three minutes available and so on. The cable 14, which can be a so-called"curly cable"so that it can be extended, is connected through terminals 32 and 34 of the cradle 12 to the cable 18. Data communication between the unit 16 and cell phone 10, and the supply of charging power from the unit 16 to the cell phone 10, is thus through the two cables 14, 18 and the terminals 32,34.

Turning now to the unit 16, this has a number of controls shown at 36, 38 and 40 and an array of lights 44,46, 48,50 and 52. The light 44 is red and the lights 46,48, 50 and 52 are green. The controls have the following functions:- Control 36. This enables the taxi driver to set the amount of call time purchased. As he does this the appropriate lights on his unit 16 and on the cradle 12 are illuminated. In addition to being illuminated the lights can flash.

Control 38. This is the enter control and is activated as soon as the desired call time has been entered.

Control 40. This is the reset control and, when actuated, deletes all previous settings,.

The cell phone 10 can be in a housing which includes a manually operable lock (not shown). The cell phone can only be removed from the housing once the lock has been released. The driver releases the lock to enable him to remove the cell phone from the housing and use it away from the taxi.

The operation of the system described is as follows. When a passenger wishes to make a call, the duration is decided upon by the passenger (one to five minutes) and the taxi driver is paid. The driver then uses the control 36 to set the duration of the call, for example, by depressing the control once for each minute purchased. The red light and the appropriate number of green lights illuminate.

The passenger then removes the cell phone 10, still locked in its housing, from the cradle 12 and makes a call, using the keypad and other functions of the cell phone, following standard procedures. As the called number answers, a confirmatory signal is made available at the data port of the cell phone. This is transmitted to the unit 16 and is used to start the countdown timer.

As the call progresses, the lights go out in sequence. More specifically, as each minute of the call is used up, one light is extinguished both at the driver's unit and on the cradle. When only the red lights are on, the passenger knows that less than one minute is left. The call is terminated, and the red light extinguished, at the end of the period paid for.

If the call is terminated by the passenger before the paid for time has been used up, the driver can activate the re-set control 40 whereupon any lights still illuminated are extinguished. The system is then ready for a further call to be made.

Should the call fail to connect, and the cell phone be returned to the cradle unused, the driver resets the system and refunds the prepaid amount.

It will be understood that the SMS function is automatically available on the cell phone. This can be used by purchasing, say, one minute of phone time, keying in the message and sending it. The signal acknowledging that the message has been successfully sent can be made available at the data port of the cell phone, transmitted to the unit 16 and used to return the system to standby mode.

The system can be configured so that if, upon the passenger terminating a call, more than, say, sixty seconds remain of the paid for time, a second call can be made. If this facility is available the system does not reset upon the first call being terminated provided more than a minimum amount of time is still available.

Incoming calls can be directed to voicemail so that the driver can retrieve them later.