Field of the Invention

The present invention relates to telephone systems and, in particular, discloses an arrangement by which a telephone system can be more readily used in public situations without the inherent problems associated with providing public telephones including the cost of their installation and upkeep. Background Art

Almost all telephone systems throughout the world include, in one form or another, a public telephone by which persons in public locations may access the telephone system through the deposit of moneys into a pay telephone type device. When serviceable, such systems are reliable and are reasonably well used.

However, public pay telephones are often subject to vandalism and the like which can render the service provided by them at best unreliable, and sometimes, dangerous. Furthermore, in Australia the cost of installing a public telephone booth is generally between A$3,000-A$5,000 once appropriate cables are run, the booth installed and appropriately lit, and a bulky vandal resistant pay telephone installed. Accordingly, such installations are not inexpensive and to be effective, it is necessary to provide a network of installations generally in locations where the public congregates such as shopping centres and the like. However, such installations are still prone to vandalism in spite of the costly efforts that have been made to make them vandal resistant.

It is therefore an object of the present invention to provide a public telephone system which substantially ameliorates the prospect of vandalism yet permits users ready access to such system. Summary of the Invention

In accordance with the present invention there is disclosed a public telephone system comprising a public telephone terminal and a portable telephone handset carried by a user thereof, said terminal comprising a barrier which separates said user from a connection to a public telephone network to which access by said user using said handset is desired, said barrier having a coupling location through which a coupling device of said handset interfaces with a complementary coupling device interconnected to said telephone network. Preferably, the barrier and coupling location are configured in a vandal resistant manner to ameliorate the effects of vandalism of said terminal. In one embodiment, the coupling device and complementary coupling device are formed by plug and socket arrangement with the barrier including an aperture through which the plug is insertable, whereby the plug is adapted to open a shutter that normally closes the aperture to protect same from vandalism.

Alternatively, remote or non-physical coupling across the barrier can be used wherein the coupling device and complementary coupling device communicate across

and through the barrier to provide a telephone connection. Remote coupling can be achieved using optoelectronic or ultrasonic transmitters and receivers, or using a split transformer arrangement.

Generally, the coupling device is retractable via a cable into the handset to form a unitary package. Also preferably the coupling device includes an attachment arrangement for removably affixing same to the coupling location. A magnet can be used, for example. A hook switch apparatus can be provided on the network side of the barrier to form a closed telephone circuit when the coupling device is appropriately positioned. The invention also includes, in other aspects, the telephone handset configured for use with the terminal, and the terminal itself. Brief Description of the Drawings

A number of embodiments of the present invention will now be described with reference to the drawings in which: Fig. 1 is a partially cut-away perspective illustration of the system of one embodiment;

Fig. 2 is a schematic cross-sectional illustration of a public telephone terminal configured in a remote manner of another embodiment;

Fig. 3 is a schematic representation of a generalised embodiment of the present invention;

Fig. 4 is a schematic block diagram representation of a portable telephone handset configured for use with the preferred embodiments;

Figs 5 and 6 are perspective views of the handset of Fig. 4 in both opened and closed configurations respectively; Fig. 7 is a sectional elevation view of one embodiment of a coupling arrangement for use with the handset of Figs 3 to 6;

Fig. 8 is an alternative embodiment of a coupling arrangement for use with the handset of Figs 3 to 6;

Fig. 9 is an alternative embodiment of a coupling arrangement for use with the handset of Figs 3 to 6;

Fig. 10 is an alternative embodiment of a coupling arrangement for use with the handset of Figs 3 to 6;

Fig. 11 is a schematic block diagram representation of another embodiment;

Fig. 12 is a schematic circuit implementation of Fig. 11; Figs. 13 and 14 are views similar to Figs. 11 and 12 respectively, but of another embodiment; and

Fig. 15 illustrates a coupling configuration that can be used with the embodiments of Figs. 9 and 11 to 14.

Fig. 1 illustrates a public telephone terminal location 100 which includes three public telephone terminals 101, 102 and 103 that face into a public area for access by a user 104. The terminals 101-103 are configured within a wall 105, of a shop for example, and each incorporates a wired line interconnection 106 (only one of which is seen in Fig. 1) to a public telephone network. The user 104 carries a portable telephone handset 107 from which a cord 108 extends. Arranged at the periphery of the cord 108 is a coupler 109 which is configured to mate or otherwise interface with one of the telephone points 101-103. The telephone points 101-103 each include a respective arrangement 110 (only one of which is seen in Fig. 1) that permits communications interconnection between the line 106 and the handset 107. The arrangement 100 is configured so as to not be accessible by the user 104 to thereby provide resistance to vandalism.

Fig. 2 illustrates an alternative configuration where a public telephone terminal 115 is arranged in a supporting pole 116 of a street lamp 117. In such an embodiment, it is usually unlikely that a wired connection to a public telephone network will be available at or near the pole 116. In Fig. 2, the public telephone terminal 115 interconnect with a fixed location cellular radio transceiver 117 arranged within the pole 116 and able to communicate radio frequency telephone signals with a public cellular telephone network via an antenna 118. Also, in view of this embodiment being configured in a light pole, mains power can be obtained via a mains supply 119 which is generally used to power the lamp 120. In this embodiment, the mains supply 119 can be used to power the fixed cellular transceiver 117 and, where appropriate, any electronics package 121 associated with the public telephone terminal 115. The package 121 has an output 122 which connects to the transceiver 117 and conveys telephone speech signals therebetween.

Having now described a general configuration of a number of embodiments of the invention, a more specific configuration can be described.

With reference to Fig. 3, a telephone terminal configuration 1 is shown in a side sectional elevation view which includes a public telephone terminal 2 which permits a person in possession of a private portable telephone handset 3 to interconnect with a pair of telephone exchange lines 7 arranged on a exchange side 6 of a substantially vandal resistant wall 4, the handset 3 being located on a subscriber side 5 of the wall 4. The wall 4 is configured to be vandal resistant so as to protect from vandalism components provided on the exchange side 6, and in particular the exchange lines 7 which connect to a public switched telephone network (PSTN).

It is noted that the exchange lines 7 of the PSTN, and the cellular transceiver of the cellular network, act as a means by which access is gained to a public telephone network that includes either one, or both of the PSTN and the cellular network, but can also include satellite networks, optical networks and the like.

Shown extended from, and forming part of the telephone handset 3, is a coupling device 8 which interconnects with the handset 3 by means of a cable 9. The coupling device 8 is configurable at a coupling location 10 in the wall 4 where access to the exchange side 6 can be made. Arranged on the exchange side 6 at the coupling location 10 is a complementary coupling device 11 which supplies a pair of connecting lines which include a hook switch 12 which emulates the role of a hook switch in a standard telephone handset.

Depending upon the particular application, the connecting lines 13 can connect directly to, or form, the exchange lines 7. Alternatively, where it is necessary for the complementary coupling device 11 to have some electronic processing capability, an optimal interface unit 14 can be provided to interface telephone signals directly onto the exchange line 7. An optional local power supply 15 can be provided where it is necessary for additional power to be provided to the interface unit 14 and/or the complementary coupling device 11. However, where possible it is preferred that components provided on the exchange side 6 are powered from energy provided by the exchange line 7.

With the configuration of Fig. 3, the person carrying the telephone handset 3 can approach the public telephone terminal 2 and attach the coupling device 8 at the coupling location 10. Generally, the attachment of the coupling device 8 acts to close the hook switch 12 thereby completing a communication the circuit formed with the exchange line 7. The telephone handset 3 can then be operated whereby the coupling device 8 and the complementary coupling device 11 communicate through the barrier provided by the vandal resistant wall 4. In this manner, access to the exchange line 7 is achieved whereby a person using the telephone handset 3 can implement a telephone call.

So that the cost of the telephone call can be charged, the system is configured such that the telephone handset 3 contains an identity code of a particular telephone account and the cost of the telephone call made at the public telephone terminal 2 is charged to that account and billed in an appropriate manner. Where desired, a personal identification number (PIN) can be used to ensure valid use of a telephone account number prior to the system connecting a telephone call.

Turning now to Fig. 4, the handset 3 is shown schematically and includes a standard telephone circuit 16 to which are connected each of a loud speaker 17 and a microphone 18 which perform their usual functions. A key pad assembly 19 is also provided which incorporates dialling keys 20, a number of preset keys 21 for accessing preset telephone numbers, and a display 22. A read only memory (ROM) 23 is also provided which can be used to store the preset numbers 23 as well as store a telephone account number corresponding to the telephone handset 3.

Where the handset 3 is not able to be powered from the exchange lines 7, a battery pack 24, which is preferably rechargeable, is provided to energise the handset 3. The telephone circuit 16 connects to a cord line retractor 25 which permits the cable 9 to be retracted when not in use. The coupling device 8 incorporates both a telephone coupler 26 and a physical coupler 27. The coupling device 8, when the cable 9 is spooled, integrates with the bulk of the telephone handpiece. Thus, when not in use, the handset 3 forms a unitary module which can be easily stowed. When use of the telephone handset 3 is desired, the coupling device 8 can be detached from the body of the handset 3 and the cable 9 extended until the physical coupler 27 is located at the public telephone terminal 2 formed in the wall 4. The telephone coupler 26 provides the actual communications between the telephone handset 3 and the exchange side 6.

In Figs 5 and 6, one configuration of the telephone handset 3 is shown where the handset 3 is formed by a housing having two halves 28 and 29 interconnected by a hinge 30. As seen, the various integers described with reference to Fig. 4 are distributed about each of the halves 28 and 29 with the coupling device 8 being detachable from the half housing 29 with the cable 9 extending from the cord line retractor 25.

It will be appreciated by those skilled in the art that the significant advantage of the present invention lies in the provision of a vandal resistant coupling across or through the coupling location 10 provided in the vandal resistant wall 4.

Fig. 7 shows one embodiment of a coupling configuration 35 which provides for physical and electrical connection between the cable 9 extending from the telephone handset 3 and the exchange line 7 which thereby permits the handset 3 to be powered directly from the exchange line 7. As seen, the wall 4 includes a small aperture 36 through which a 2-conductor 3 mm plug 37 can be inserted to contact a complementary socket 38 arranged on the exchange side 6. Such an arrangement permits direct physical and electrical connection between the cable 9 and the exchange line 7.

The coupling configuration 35 is made substantially vandal resistant through provision of a shutter 39 arranged on the exchange side 6 of the aperture 36. The shutter 39 is connected to a hinge arrangement 40 which is biased by an annular magnet 41 placed about the socket 38. The magnet 41 is located to complement a similar magnet 42 arranged about the plug 37 which is locatable in a recess 43 in the wall 4 arranged about the aperture 36. In this manner, the recess 43 permits accurate locating of both the magnet 42 and the plug 37 thereby permitting its insertion through the aperture 36. Furthermore, when the magnet 42 is positioned, the magnet 41 is attracted towards the aperture 36 thereby causing the hinge arrangement 40 to pivot lifting the shutter 39 away from the aperture 36 to expose the socket 38 to the plug 37. In this manner, the plug 37 can be pushed home into the aperture 36 to make appropriate contact within the socket 38. This can be assisted by a spring bias mounting

configuration 44 by which the plug 37 and magnet 42 are interconnected to form a unitary coupling device 45 which can be retracted into the telephone handset 3.

Also illustrated in Fig. 7 and connected in series with the exchange line 7 is a reed switch 46 which is magnetically operable upon movement of the magnet 41 towards the aperture 36 to close thereby completing the circuit formed by the exchange line 7 and the cable 9 supplying the telephone handset 3. Alternatively, the hook switch function can be provided by the socket 38 including contacts that are closed upon insertion of the plug 37.

Once appropriate connection is made, a telephone call can be instigated using the handset in the manner earlier described. Initially, the user preferably depresses one of the preset keys 21 which incorporates the telephone account number to which the call is to be charged and then enters an appropriate PIN number. Once the PIN number is accepted, a telephone number may then be dialled.

The embodiment of Fig. 7 has the specific advantage that electrical power for the operation of the telephone handset 3 can be derived from the exchange line 7.

However, it does present, through the public telephone terminal 2, a means by which vandals may, with effort, cause damage to a mechanism as well as to the exchange line 7.

The embodiments of Figs 8, 9 and 10 show various arrangements in which there is no direct electrical interconnection between the subscriber side 5 and the exchange side 6 of the wall 4 whereby remote communication through the wall 4 is provided to ensure a substantially vandal resistant environment.

Turning now to Fig. 8, the wall 4 is provided with two windows 50 and 51 which are separated by an opaque barrier 52. Positioned about windows 51, 52 on the subscriber side is a recess 53 which permits the locating of a magnetic coupler 54 which incorporates an optoelectronic transmitter 55 and a corresponding optoelectronic receiver 56, both of which being positioned adjacent corresponding one of the windows 50, 51.

Positioned on the exchange side of the windows 50 and 51 are complementary optoelectronic receivers and transmitters 57 and 58 which couple to an interface unit 59 which supplies the exchange line 7. A magnetically operable hook switch 60 is also provided in the manner similar to the arrangement of Fig. 7. With this configuration, the optoelectronic transmitters and receivers 55-58 can be energised respectively by the interface unit 59 and the telephone handset 3 to provide appropriate coupling of voice signals through the windows 50, 51 provided in the vandal resistant wall 4. This can be achieved using frequency modulation permitting detection using phase locked loops using a carrier frequency of approximately 100 kilohertz thereby easily supporting a telephone bandwidth of 3 kilohertz. Other arrangements for driving the optoelectronic devices 55-58 can be used as known in the art. It will also be appreciated that with this

embodiment it may be necessary to power the interface unit 59 from an additional energy source such as the local power supply 15 of Fig. 3. However, through using low power devices, and in view of the absence of the need for a ringing circuit in the embodiments of this specification, it is possible that the interface unit 59 and its associated components can be energised using current drawn from the exchange line 7. Fig. 9 illustrates a further embodiment which utilises electromagnetic coupling through the vandal resistant barrier 4. In this embodiment, the barrier 4 is manufactured of materials that are transparent to electromagnetic flux, and coupling is provided by a split transformer arrangement comprising one transformer half 70 which connects to the cable 9 leading to the telephone handset 3, and a complementary transformer half 71 which connects to the telephone line 7 via a magnetically operable hook switch 72. In this embodiment, the transformer halves 70 and 71 can be formed using miniature pot core type assemblies which can be energised to provide a high degree of coupling between the two, yet have relatively small size and are thereby conveniently located within a portable telephone handset.

In the embodiment of Fig. 10, acoustic coupling is provided in a manner similar to the optoelectronic coupling of Fig. 8. In this embodiment, the barrier 4 is provided to be substantially acoustically transparent and a coupling device 80 is provided which incorporates an acoustic transmitter 81 and an acoustic receiver 82. Complementary devices are arranged in a complementary coupling device 83 provided on the exchange side of the wall 4 which incorporates a hook switch as before. In the acoustic coupling embodiment, preferably ultrasonic transmissions are used at different centre frequencies thereby ensuring distinction between signals crossing the wall 4 in either direction. It will be appreciated by those skilled in the art that the foregoing arrangements permit a public telephone installation to be provided without the need to provide a telephone handset permanently configured at that location. All that is required is a means for connecting a portable telephone handset carried by a user of the system and which permits coupling to a public telephone terminal in either a physical manner as shown in Fig. 7 or in a remote manner as shown in the embodiments of Figs 8, 9 and 10.

The preferred embodiments of the public telephone terminal are implemented using the split transformer configuration of Fig. 9 for which a number of arrangements are shown in Figs. 11 to 15. In Fig. 11, a public telephone arrangement 125 is shown which includes a connection point 130 connected to a PSTN line 131 and a mains supply 132. The connection point 130 couples telephone signals across a vandal resistant isolation barrier 139 using a split transformer having one half 136 interconnected with the

connection point 130 and another half 141 forming part of a personal telephone handset 140 carried by a user of the arrangement 125.

The connection point 130 includes a noise filtering and protection unit 133 which is arranged to provide sufficient immunity to line coupled noise and to prevent high rise-time impulses from lightning strikes and other transients being induced into the circuitry of the connection point 130. Such an arrangement can include the appropriate transient protection devices such as metal oxide varistors, or spark gap arresters. Furthermore, if the isolation/vandal resistant barrier 139 is of sufficiently high electrical break-down characteristics so as to meet telephone authority requirements, the inclusion of a isolation transformer between the PSTN line 131 and the connection point 130 may not be required, however dielectric isolation can be included in the noise filtering and protection unit 130 as needed. The unit 133 outputs to a speech and line control block 134 is provided to activate the PSTN line 131 subsequent to detection of the connection of a handset, which is performed by a handset detection arrangement 137. The speech and line control block 134 acts to draw loop current from the PSTN line 131 to provide a dial tone to the personal handset 140. Where appropriate, the speech and line control block 134 can also include an amplification arrangement so as to ensure the PSTN line 131 is not overloaded and to ensure adequate coupling over the barrier 139. In this embodiment, electrical power for both the connection point 130 and personal handset 140 is derived from the mains supply 132 by means of a power supply and barrier drive unit 138. The unit 138 is configured to rectify the mains supply 132 in a conventional manner and to directly supply the components of the connection point 130. In addition, it is configured to output an above audio frequency signal developed by a low impedance drive circuit driving the transformer half 136 to couple same across to the personal handset 140. For example, in most cases, the telephone bandwidth is between 300Hz and 3000Hz. Accordingly, the above audio frequency barrier drive signal can be between about 10kHz and typically 100kHz. In order to prevent the barrier driver signal impinging upon the telephone communication circuitry, a blocking filter 135 is inserted to allow telephone signals to pass between the transformer half 136 and the speech and control block 134. Typically, the blocking filter 135 comprises a low-pass filter having minimal attenuation in the audio band (eg. 300Hz-3000Hz), but having significant attenuation at the frequency of the barrier drive signal (> 10kHz). Furthermore, the role of the blocking filter 135 can be further supplemented in the noise filtering and protection unit 133 so as to ensure signal requirements set by the local telephone authority are met.

The handset detection circuit 137 is arranged to detect the presence of the personal handset 140 at or near the barrier 139 so as to cause the PSTN line 131 to be looped.

The personal handset 140 includes the transformer half 141 which couples both telephone audio signals and barrier drive AC signals across the barrier 139. The above audio frequency barrier drive signals are supplied to a power supply unit 140 which includes filtering and rectification components arranged to provide a DC signal necessary to supply electronic circuitry within the handset 140. A blocking filter 143, which can be identical to the blocking filter 135, is provided to allow telephone audio signals to pass to a speech circuit 144 whilst preventing the barrier drive signals from impinging upon the speech circuit 144. Where appropriate, the power supply 142 can include a low-dropout regulator which can be arranged to supply both analog and logic circuitry within the handset 140. The speech circuit 144 can be formed of a integrated circuit device of reduced implementation to those commonly used in modern telephone handsets. A reduced implementation is sufficient as the handset 140 is not configured to receive telephone calls and therefore there is no requirement for a ringing circuit within the handset 140. The speech circuit 144 connects to an earpiece 145 and a microphone 146 in the usual manner. An example of a speech circuit 144 that can be used is the Motorola MC34014 device which has a DTMF input capability. Other integrated circuit devices include pulse style and those with incoming ring facilities. An access code dial circuit 148 interconnects a dial pad 149 with the speech circuit 144. The circuit 148 is configured to minimise the component count in the dial pad 149 and is configured to forward dialling signals to the speech circuit 144 for coupling same across the barrier 139 for the initiation of a telephone call. Furthermore, the circuit 148 can be configured to detect the application of electric power to the handset 140 via the power supply 142 and, after a preset delay, automatically send an appropriate security code to the telephone network exchange via the PSTN line 131 to enable dial- out access. More particularly, coupled with the security code can be an account code, whereby calls made from any particular personal telephone handset 140 are charged to a corresponding telephone account.

To ensure non- volatile storage of network access codes, account codes and abbreviated dial memories, a back-up supply 147 can be included and take the form of a long-life dry cell battery.

Turning now to Fig. 12, a specific implementation of the arrangement of Fig. 11 is shown where a two-wire telephone line 131 has connected across it a three- terminal protection device such as a gas arrester 150 or a configuration of metal oxide varistors. The line 131 connects to the speech line control block 134 which is formed in this embodiment using a bridge rectifier 151, a relay 152 and an electronic load formed by components 154-158. The relay 152 is closed by a handset detection circuit 153 and operates as the hook switch of a standard telephone handset such that line current is drawn by the circuit components 154-158. The components 154-158 include a Darlington connected pair of transistors 156 biased from a resistor 154 whose bias

voltage is filtered using a capacitor 155. Current drawn by the transistors 156 is dumped into a resistive load 157. A zener diode 158 clamps the maximum voltage applied across the electronic load. A capacitor 159 is used to AC-coupled telephone communication signals such as dial tone and speech to the split transformer half 136. The blocking filter 135 is implemented by an inductor 160, and two series combinations of a capacitor 161 and resistor 162, arranged in a π-configuration.

The mains supply 132 inputs to a conventional power supply 154 which includes an isolating transformer and rectifying components. The power supply 154 supplies electrical energy to an AC drive 155 and the handset detection circuit 153. The AC drive 155 provides a relatively high frequency signal, for example in excess of 10 kHz, to the transformer half 136 to permit coupling of a power signal across the split transformer 136,141. As shown in Fig. 12, the relatively high frequency power signal is blocked from impinging upon a speech circuit processor 166 by a blocking filter 143 corresponding to the blocking filter 135. The power signal is rectified by a diode 162 and subsequently smoothed by a π-filter 163 including an inductor 164 and two capacitors 165. The DC level output from the π-filter 163 is supplied to electronic circuitry within the personal handset 140 which additionally includes a 4-bit microcontroller 167, a clock extraction circuit 168 and the dial pad 149. The speech circuit device 166 can be the Motorola MC34014 device, or other suitable device, and the microcontroller 167 can be a known device which includes a built-in DTMF generator and therefore is able to directly couple to the speech circuit device 166. The clock extraction circuit 168 operates to supply clock and timing signals to the microcontroller 167. A backup battery 169 is provided and can be in the form of a small button-cell. The handset detection arrangement 153 which actuates the relay 152 can be configured to detect a change in the level of the AC drive 155 which occurs when the transformer half 141 is coupled to the barrier 139 and therefore places a load on the drive 155. The handset detection circuit 153 can therefore include an amplitude sensitive arrangement. The arrangement of Figs. 11 and 12 need not be powered directly from an AC mains supply 132, but can alternatively be powered from any other available supply, such as a solar charged battery supply 170 such as that illustrated in phantom in Fig. 11. Such an arrangement may be useful where no mains supply 132 is conveniently available or in system specifically configured without self-powered personal handsets. Fig. 13 shows an arrangement similar to Fig. 11 with corresponding blocks being given corresponding reference numerals. In this embodiment however, the arrangement is configured to operate without a power supply being provided from the telephone network side of the barrier 139. In this manner, a connection point 180 is powered entirely from the PSTN line 131, and a personal handset 190 is configured,

not unlike the handset 140 of the previous embodiment but additionally including a main battery supply 191 coupled to the circuitry by a switch 192. All other components within the handset 190 can be configured in a corresponding manner to the handset 140. A specific arrangement of the battery powered system 175 of Fig. 13 is shown in Fig. 14, where again similarly numbered components perform the same function. In this embodiment, the battery supply 191 can be interchangeable to permit consistent use of the handset 190. Also, in view of the telephone network side of the barrier 139 being powered directly from the line 131, an alternative arrangement for the detection of the handset 190 is provided. As shown, a reed switch 181 is provided which is coupled by physical association indicated at 182, to a magnet incorporated in or with the transformer half 141 of the handset 190, not seen in Fig. 14, but shown in more detail in Fig. 15.

In the arrangement of Fig. 15, the barrier 139 is bolted about an aperture 200 in a wall 201 which can be the wall of a building or other structures such a lamp pole or the like. Vandal resistant bolts or other fasteners 202 are used to fasten the barrier 139 to the wall 201. In this embodiment, the barrier 139 is frusto-conically shaped to receive a plug casing 203 which extends from the telephone handset 190 and is interconnected therewith by a cable 204. The casing 203 encloses one half of the split transformer. In this embodiment, the split transformer is formed by a potcore assembly 205 having halves 206 and 207 arranged on either side of the barrier 139, the half 207 being configured within the plug casing 203. Each of the transformer halves includes a transformer winding 209 and 210 respectively, the latter of which connects to the cable 204. The winding 209 connects directly to the blocking filter 135 of the embodiments of Figs. 11 to 14. In this embodiment, part of the split transformer core 207 arranged within the plug casing 203 includes a magnet 211 which is configured to close a reed switch 212, configured in a corresponding position to permit actuation either in the vandal resistant barrier 139 as illustrated, or immediately adjacent same alongside the other half of the split core 206. The reed switch 212 interconnects between the rectifier 151 and the capacitor 159 as illustrated in Figs. 12 and 14 and is closed by the magnet 211 being placed in the vicinity thereof. The vandal resistant barrier 139 is configured to pass magnetic flux between each of the cores 206 and 207 thereby permitting the communication of telephone acoustic signals and/or higher frequency power signal as used in the embodiments of Figs. 11 and 12. As also seen in Fig. 15, the barrier 139 includes a coupling location 213 configured as a recess which is shaped to receive the plug casing 203 and retain same whilst the telephone call is being made. The barrier can include a bevelled face 214 which acts to guide the plug casing 203 into the recessed coupling location 213. Where appropriate, to ensure correct locating of the plug casing 203 within the recessed coupling location 213, complementary keyway

and/or tongue and groove arrangements can be provided on the plug casing 203 and the coupling location 213.

It will be apparent from the foregoing, that a number of arrangements are provided which permit public telephone services to be provided at substantially reduced costs to that of existing systems and that are less prone to vandalism than existing systems. Furthermore, any of the embodiments described need not be connected directly to a wired telephone system but can, as illustrated in Fig. 2, connect directly to a fixed cellular transceiver device 117 which permits coupling to the public switch network or other cellular networks. It will be further appreciated that in view of such an arrangement involving only the instigation of telephone calls from a portable telephone handset, there is no need for that telephone handset 3 to be provided with a ringing circuit or for the exchange line 7 to supply a ringing signal thereto. This permits a lower power consumption on both sides of the vandal resistant wall 4 by any electronic devices that are used.

In order for the embodiments described to operate within a PSTN network, the telephone network exchange should be configured with some form of call re-direction or coded access facility.

With call re-direction, a controller arranged at the exchange is configured to receive the access code dialled or otherwise sent from the personal handset 140,190, verify its content, and identify any charge account status. Any successive digits dialled are then re-directed to the exchange for processing with call charges being referred to the identified account.

With a coded access facility, the exchange is provided with a controller on each line allocated to a public connection point. In this case, the personal handset is not permitted communication with the exchange until the controller receives a valid access code which is checked against a local or remote database.

In another embodiment (not illustrated), the barrier 139 need not be configured in a wall, but rather can be formed by an enclosure for the entire connection point 130,180. The enclosure can be placed on a trolley or like support and conveniently positioned within or outside a retail location, for example, with the line 131 extending from the enclosure to a standard telephone outlet within the retail location. With this arrangement, the proximity of the retailer can monitor use of the arrangement 125 to prevent vandalism. The foregoing describes only a number of embodiments of the present invention and, modifications, obvious to those skilled in the art can be made thereto without departing from the scope of the present invention. For example, in remote locations where a direct connection to an exchange line 7 is not available, the exchange side of the public telephone terminal 2 can be formed by a cellular radio telephone

installation which can be set into operation in a similar manner to that described above. Solar energy power for any of the embodiments described can also be used. Also, hook switch operation can be electronically actuated by the user via the handset 3.