Abstract:
A telecommunication connector for a distribution point comprises a base part and a detachable configuration module, the configuration module being able to take a plurality of dispositions with respect to the base part, the base part having connection means to (i) a telecommunications cable from an exchange, (ii) a cable to a further distribution point, and (iii) a cable to a consumer, wherein the configuration module causes electrical connection from the exchange to the further distribution point in a first disposition but not in a second disposition. This permits the installer who is connecting a new consumer to disconnect the unnecessary part of the wire forming the relevant pair when activating the service whilst leaving intact the investment in the network. The configuration module can also contain protective devices for the line, such as three or five pin protection, over current devices and over voltage devices, or other active electronic elements. It is further preferred that in the first orientation, the configuration module causes electrical connection between the exchange and consumer to be broken.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to an electrical connector for use in telecommunications. 
     BACKGROUND ART 
     Telecommunications utilities provide a network of cables through which the calls they handle can be routed. These cables can be of optical fibre or conductive copper, but the end of the network close to the subscriber is usually copper. As the network is usually of necessity laid prior to application for service by subscribers, it is necessary to provide a flexible network which can be reconfigured as required by the pattern of subscribers, and to allow for disconnection, reconnection, and connection of new subscribers. 
     Accordingly, the usual practice of a utility when laying a new local network is to install a multi-pair cable, such as a  400  pair cable, from the exchange past a number of distribution points. Each individual pair is accessible at several distribution points, so the resulting network is highly flexible. This practice is acceptable for voice telephony and low speed data use. 
     A distribution point is typically housed in a cabinet at the roadside, although other arrangements are used, and contains an array of connectors at which wire pairs leading to the consumer premises can be attached to form a spur. Each spur is tapped into a pair of the cable, enabling service to be provided. If that service is discontinued, the relevant spur is removed and the connector becomes available for use in providing service to another consumer. 
     However, when a connection is made at a distribution point other than the last, the additional cable between the chosen distribution point and the last acts as a further spur of cable off the electrical path between the exchange and the subscriber. In high speed data uses such as ISDN and DSL/ADSL, this further spur is one of the factors placing an upper limit on the available speed. It is therefore necessary on occasions to “clean the copper”, ie locate the spurs of unused copper and cut them off. This is a lengthy process, estimated at costing $800 per pair, and also reduces the flexibility of the network to meet future demand. If the service to that subscriber is discontinued then that pair can only be reused if another consumer adjacent the same distribution point happens to request service. Even then, it is unlikely that sufficiently accurate records could be kept to enable that pair to be re-used. 
     SUMMARY OF THE INVENTION 
     The present invention therefore provides a telecommunications connector for a distribution point comprising a base part and a detachable configuration module, the configuration module being able to take a plurality of dispositions with respect to the base part, the base part having connection means to (i) a telecommunications cable from an exchange, (ii) a cable to a further distribution point, and (iii) a cable to a consumer, wherein the configuration module causes electrical connection from the exchange to the further distribution point in a first disposition but not in a second disposition. 
     This permits the installer who is connecting a new consumer to disconnect the unnecessary part of the wire forming the relevant pair when activating the service. If service should be discontinued, the pair can be reconstructed. This leaves intact the investment in the network. Such an operation can also be carried out by an installer without assistance from the specialist cable engineer required for cleaning the copper. By integrating the reconfiguration into the connector unit a reliable and reusable network is achieved which can be manipulated by non-specialist staff. 
     The configuration module can also contain protective devices for the line, such as three or five pin protection, over current devices and over voltage devices, or other active electronic elements such as (but not limited to) line termination devices, remote identification devices, and so on. 
     It is further preferred that in the first orientation, the configuration module causes electrical connection between the exchange and consumer to be broken. Thus, the exchange is always connected to either a consumer or a further distribution point (except at the last), but potentially never both. 
     A removable configuration module can thus be provided with seven electrical connections, being two each for the pairs leading to the exchange, further distribution point and consumer, together with an earth. Thus, in another aspect the present invention also relates to a seven pin protector module for a telecommunications line. However, designs with less than 7 pins or more than seven pins are possible. Accordingly, the present invention also relates to a five pin protector module for a telecommunications line which is adapted to seat in a seven pin socket of a base unit. However, designs with less than 7 pins or more than 7 pins in the base unit are again possible. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the present invention will now be described with reference to and/or as illustrated in the accompanying figures, in which; 
     FIG. 1 is a schematic illustration of a local telephone network; 
     FIG. 2 is a schematic illustration of the electrical structure at a distribution point according to the prior art; 
     FIG. 3 is a schematic illustration of the electrical structure at a distribution point according to the present invention, in a first orientation; 
     FIG. 4 is a schematic illustration of the electrical structure at a distribution point according to the present invention, in a second orientation; 
     FIG. 5 is a perspective view from above of a base unit according to a first embodiment of the present invention; 
     FIG. 6 is a perspective view from below of a configuration module according to the first embodiment; 
     FIG. 7 is a cut away view showing the electrical contacts and surge arrestor only of the base unit and the configuration module of FIGS. 5 and 6; 
     FIG. 8 is a perspective view from above of the base unit of the first embodiment showing the electrical conductors of the configuration module in place; 
     FIG. 9 is a perspective view from above of the configuration unit of the first embodiment; 
     FIG. 10 is a sectional view of a second embodiment of the present invention, in a first disposition; 
     FIG. 11 is a sectional view according to FIG. 10 but showing a second disposition; 
     FIG. 12 is a schematic view of the electrical connections to the base unit according to a third embodiment; 
     FIGS. 13 and 14 are top and sectional views of the electrical conductors of an unprotected configuration unit according to the third embodiment, respectively, FIG. 14 being a section on XV of FIG. 13; 
     FIGS. 15 and 16 are top views of the mating parts only of the electrical conductors of both the base and configuration units of the third embodiment, when connected in a first and second disposition respectively; 
     FIGS. 17 and 18 are top and side views of the electrical conductors of an protected configuration unit according to the third embodiment, respectively, FIG. 18 being a section on XIX—XIX of FIG. 17; 
     FIG. 19 is a perspective view of the third embodiment, showing the base unit and the conductors only of the configuration unit; 
     FIG. 20 is a perspective view of the third embodiment, showing the base unit partially cut away and the conductors only of the configuration unit; 
     FIG. 21 is a perspective view of the third embodiment, cut away to show the conductors only of the base and configuration unit together with the connection means; 
     FIGS. 22 and 23 are views of the third embodiment from beneath, showing alternative connection routes; 
     FIG. 24 is a perspective exploded view of a fourth embodiment; 
     FIG. 25 is a perspective view of the conductive components of FIG. 24; 
     FIG. 26 is a perspective view of the operative parts of FIG. 24, in a first state; and 
     FIG. 27 is a perspective view of the operative parts of FIG. 24, in a second state. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Referring to FIG. 1, a typical local network includes a 400-pair cable  100  which enters the area to be served and splits into branch cables such as  102  which contain a lesser number of pairs. Each branch cable is connected to a number of distribution points such as those at  104  and  106 . The cable branches repeatedly at branch points such as  108  so as to serve a large number of such distribution points. An individual pair, such as (for example) pair number  81  of the  400  may itself branch at a number of such branching points  108  and be made available at a number of distribution points on that branch and on other branches. FIG. 1 shows the pair numbers which (in this example) are made available on each branch or segment of the line. The distribution points at which pair no.  81  is available are indicated with a *. It will be seen that this pair is available at six distribution points and branches twice along its length. 
     This branching does not present a problem in voice telephony and low rate data use. The demands placed on the electrical properties of the pair are sufficiently light to cope with such branching. However, high speed data use such as ISDN and DSL/ADSL demand a better response and the signal echo generated by branches such as are shown in FIG. 1 produces an unacceptable impairment of the electrical properties. Therefore, assuming that the subscriber was connected to the network via pair  81  at distribution point  106  it will be necessary to locate distribution point  110  where pair  81  is also available, identify the appropriate wire pair and cut it. There will be a short branch between branching point  108  and distribution point  110 , but this is not so long to detrimentally affect the electrical properties of the pair. However, this process is lengthy and expensive since specialist cable connection staff must be called upon, and involves a permanent degradation of the network capabilities. 
     FIG. 2 shows the typical electrical structure at a distribution point. A wire pair  112  enters the distribution point and continues on through and out as  114 . Electrical connections  116  are made with each wire of the pair and brought to a connector  118  which is usually of the insulation displacement type (IDC). At the IDC connector  118 , a pair  120  is connected and leads away from the distribution point to the subscriber. 
     Where no subscriber is connected at that distribution point, the pair therefore continues undisturbed. Where a subscriber is connected, this is essentially by way of a tap on to the existing wire pair. 
     FIGS. 3 and 4 illustrate the principle behind the present invention. A wire pair  112 ′ enters the distribution point and departs as wire pair  114 ′. However, the two wire pairs are not connected together directly but instead each end at connectors  122 ,  124  respectively. A consumer pair  120 ′ also leaves the distribution point for the subscriber&#39;s premises but is connected to a third connector  126 . A configuration module is connectable to any or all of the three connectors  122 ,  124 ,  126  and contains a pair of bridging links which are able to bridge appropriate pairs. In this position illustrated at FIG. 3, the bridging links  128  bridge connections  122  and  124  and therefore link the incoming wire pair  122 ′ with the outgoing wire pair  114 ′. The subscriber pair  120 ′ is left unconnected. 
     In the second disposition shown in FIG. 4, the conductors  128  of the configuration unit bridge connectors  122  and  126  thereby connecting the subscriber pair  120 ′ to the incoming wire pair  112 ′. It is to be assumed that the incoming wire pair  112 ′ is from the exchange and the outgoing wire pair  114 ′ is to a further distribution point. Thus, in this disposition, the subscriber is connected to the exchange but the “tail” of unused wire pair is left isolated, not forming part of the circuit to the subscriber. 
     In the configuration shown in FIG. 1, it would then be a simple matter to visit distribution point  110  and change the disposition of the configuration unit in a like fashion. This could be done by unskilled staff since it does not require interference with the cabling network. Equally, the process is easily reversible should service need to be ceased to that subscriber, allowing the wire pair to be redeployed for a different subscriber at a different distribution point. This would completely clean the copper in a simple and reversible fashion. 
     FIGS. 5 to  9  show a first working example of how this might be put in practice. The embodiment consists of two main parts, a base unit  200  shown in FIG. 5 and a configuration unit  202  showing in FIGS. 6 and 9. The base unit  200  contains seven conductors  204  which are accessible on the underside of the base unit  200  via IDC connectors. These are presented within a recess  206  on the upper surface of the base unit  200  as upstanding metal blades such as  208 . Of the seven blades, six are parallel and arranged in pairs, one pair at one end of the recess  206 , one pair at the opposite end of the recess  206  and the third pair at the centre of the recess. The seventh blade  210  is presented at right angles at the centre of the recess  206  between a pair. 
     In use, the central pair  212  is connected to the wire pair  112 ′ from the exchange. The pair of connectors  214  at one end of the recess are connected to the ongoing pair  114 ′ leaving two further distribution points. The pair of blades  216  at the other end of the recess  206  are connected to the subscriber pair  120 ′. 
     The configuration unit  202  contains two conductors  218  ,  220 . These are spaced and arranged so that they will bridge the gap between either blades  212  and  214  or blades  212  and  216 . The mating surfaces between the base unit  200  and the configuration unit  202  are made symmetric under a rotation of  1800  and therefore the configuration unit  202  can be placed in any one of two dispositions so as to effect connection between the appropriate set of blade pairs. 
     Thus, when placed in the first orientation the configuration unit causes the incoming wire pair or  112 ′ from the exchange to be connected to the outgoing wire pair  114 ′ to further distribution points. When inserted in a rotated disposition, the configuration unit  202  causes the incoming wire pair  112 ′ to be connected to the subscriber  120  and disconnected from the outgoing wire pair  114 ′. Thus, the principle illustrated in FIGS. 3 and 4 is effected. 
     FIG. 8 shows the base unit  200  with the conductors  218 ,  220  of the configuration unit  202  in place and the remainder of the configuration unit  202  cut away. It will be seen that the conductors make electrical contact on one side of the blades  208 . 
     FIG. 7 shows the two units connected but with all non-conducting parts removed. It can be seen that a three pole protection module  222  such as a gas discharge tube is connected at either end to the conductors  218 ,  220  and at its centre to a further conductor  224  which grips the sides of the earth contact  210 . Thus, the configuration unit  202  is also able to offer protection to the line if desired. It will be seen that if protection is undesired for a particular line, the protection unit  222  can simply be omitted. 
     FIG. 9 shows the configuration unit  202  from above. A pair of recesses  226 ,  228  are formed into which extend the ends of the conductors  218 ,  220 . The recesses  226 ,  228  would normally be filled with a gel, grease, or other conformable material to allow environmental protection. Nevertheless, such material can be penetrated by crocodile clips or test leads of various types thereby allowing test access to the port. Thus, for maintenance purposes an engineer will be able to make temporary contact to the line to ascertain whether or not a call is in progress. If not, he can remove the configuration unit  202  and gain access to the three wire pairs therewithin. If testing of a central pair  212  reveals no connection to the exchange, the engineer can ascertain whether the pair has been disconnected at a distribution points closer to the exchange. The engineer can also test the quality of the line from blade  216  to the subscriber, thereby achieving “look both ways testing”. 
     A further embodiment of the invention will now be described with reference to FIGS. 10 and 11. A base unit  300  contains a pair of conductors  302 ,  304 . The first conductor  302  consists of a first lower IDC contact  306  which projects from the lower face of the base unit  300  and a first upper split beam contact  308  which projects upwardly of the base unit  300 . The second conductor  304  consists of a second lower IDC contact  310  which also projects from the lower face of the base unit  300 , a second upper split beam contact  312  which also projects upwardly of the base unit  300  adjacent to the first upper split beam contact, and a subscriber IDC contact  314  which projects upwardly of the base unit  300  at a location displaced from the second upper IDC contact  312 . The first and second upper split beam contacts  308 , 312  project upwardly of the base unit  300  by different lengths, the second ( 312 ) being shorter. 
     A mating face  316  is formed on the upper surface of the base unit  300  around the first and second upper split beam contacts, enclosing them within a recess  318  so as to permit environmental protection by way of gel, grease or the like, and also supporting them so as to prevent unintended deformation during use. A configuration module  320  is formed with a complementary mating face  322  to allow it to be joined to the base unit  300 . The mating faces  316 ,  322  are symmetrical under a 180° rotation and therefore the configuration unit can be attached in at least two dispositions. 
     The configuration module  320  contains a conductor  324  which has two legs  326 ,  328  extending towards the space enclosed by the mating face  322  of the configuration module  320 . The leg  328  is longer than the leg  326  by a length corresponding to the difference in length of the first and second upper split beam contacts  308 ,  312 . 
     The subscriber IDC contact  314  may be supported appropriately in a suitable structure and provided with wire carrying structures to permit a wire to be inserted and removed as necessary. The precise structure of this is not germane to the present invention and will not be described in detail. Suitable structures are illustrated and described in our earlier patent publications GB 2129630 and EP0683925. 
     This arrangement is duplicated alongside the above-described arrangement so as to allow for wire pairs to be connected. For ease of explanation, the connection of one wire of the pair will be described. The other wire of the pair connects in like fashion to the duplicate. 
     In use, the base unit  300  is installed at a distribution point and a wire pair  330  from an exchange is attached to the second lower IDC contacts  310 . A wire pair  332  leading to a further distribution point is attached to the first lower IDC contacts  306 . The configuration unit  320  is attached via the mutual mating faces in a first disposition such that the longer leg  328  mates with the (shorter) second upper split beam contact  312  and the shorter leg  326  mates with the (longer) first upper split beam contact  308 . Thus, the wire pair  330  is connected to the wire pair  332  and the pair is in effect allowed to continue through the distribution point to a more distant distribution point. 
     When a subscriber is to be connected, a test probe can be attached to the subscriber IDC contact to ensure that a call is not then in progress. Assuming not, the configuration module is then removed, breaking the pair at that distribution point. A wire pair  334  leading to the subscriber&#39;s premises is then attached to the subscriber IDC contacts  314  and the configuration unit  320  replaced in a disposition which differs by a 180° rotation. 
     In this rotated disposition, the longer leg  328  is above the first upper spilt beam contact  308  and makes contact therewith. The first upper split beam contact  308  is designed so as to be able to accept the length of the leg  328 . However, the shorter leg is insufficiently long to meet the second upper split beam contact  312  and accordingly there is no electrical continuity between the conductors  302 ,  304 . The pair therefore remains broken at this distribution point, but in a reversible fashion since connection can be remade by replacing the configuration unit  320  in its original disposition. The subscriber is nevertheless connected to the exchange since the second lower IDC contacts  310  and the subscriber IDC contacts  314  are parts of the same electrical conductors  304 . 
     A yet further embodiment of the present invention will be described with reference to FIGS. 12 to  23 . FIGS. 12 to  18  show the contacts and conductors only for clarity, FIGS. 19 to  21  show a physical arrangement corresponding to FIGS. 12 to  18 , and FIGS. 22 and 23 show the necessary connections on the rear face of the arrangement shown in FIGS. 19 to  21 . 
     Thus, in FIG. 12 there is shown a plan view of a 7-pin connection point  400 . A central pin  402  is connected to earth  404 . A subscriber pair of connectors  406 ,  408  located to one side of the central earth connector  402  are connected to a wire pair  410  leading to a subscriber&#39;s premises. On the other side of the earth connector  402  are two pairs of connectors, a first pair  412 ,  414  which are connected to a wire pair  416  leading to a subsequent distribution point and a second pair  418 ,  420  arranged either side of the first pair  412 ,  414  and which are connected to a wire pair  422  leading to the exchange. 
     A configuration module contains a pair of conductors  424 , 426  arranged and formed as shown in FIGS. 13 and 14. Each is generally U-shaped with a connection point at either free end  428 ,  430  of the U. One free end  428  is half the width of the other  430 , achieved by a step  432  along the U-profile, on one side. The other conductor  424  has a like step in a mirror image configuration. The free ends of the conductors  424 , 426  are able to mate with the connectors  406 ,  408 ,  412 ,  414 ,  418  and  420  by suitable IDC formations on the latter (not shown). 
     FIGS. 15 and 16 show how these conductive elements can be connected. FIG. 15 shows a first disposition. The conductors  424 ,  426  of the configuration unit engage with those connectors of the base unit  400  which are in an appropriate location to meet. Thus, the wider free ends  430  bridge the first and second pairs of connectors  412 ,  418  and  414 ,  420  respectively whilst the narrower free ends  428  miss the subscriber pair  406 ,  408  since the asymmetric step  432  results in the narrower free end  428  being offset. 
     In the second disposition shown in FIG. 16, the configuration module is rotated through 180°. This places the narrower free ends  428  in the vicinity of the first and second pairs of connectors  412 ,  418  and  414 ,  420  and the wider free ends  430  in the vicinity of the subscriber pair of connectors  406 ,  408 . Thus, connection is made with the subscriber pair, but the narrower free end  428  only makes connection with the second pair  418 ,  420  leading to the exchange. Thus, the subscriber is connected to the exchange but the spare tail of wire pair leading to the further distribution point is disconnected giving a clean copper connection to the exchange. 
     FIGS. 17 and 18 show the arrangement of conductors in a protected configuration module. A three pole protector  432  is located above the U-conductors  424 ,  426  such that its end caps  434 ,  436  contact the conductors. A further conductor  438  is arranged beneath the protector  432  in contact with its central earth contact  440 , and descends downwardly to make contact with the earth connector  402  of the base unit  400 , when in place. 
     FIGS. 19 to  22  show an example using the conductor arrangement principle shown in FIGS. 12 to  18 . To demonstrate alternative ways of employing this principle, a physically different layout is illustrated in which the principle and mode of operation is however identical. To aid understanding, like reference numerals but incremented by  100  are employed to denote corresponding parts. Thus, FIGS. 19 to  21  show the base unit  500  including a recess  540  in which are located the subscriber pair  506 ,  508 , first pair  512 ,  514  and second pair  518 ,  520  of contacts . The configuration module (not shown) is able to fit into the recess and contains the U-conductors  524 ,  526  (shown). 
     The subscriber pair of contacts  506 ,  508  lead to a pair of IDC contacts  542 ,  544  to which a wire pair leading to the subscriber&#39;s premises may be attached. The IDC contacts  542 ,  544  may be supported appropriately in a suitable structure and provided with wire carrying structures to permit a wire to be inserted and removed as necessary. The precise structure of this is not germane to the present invention and will not be described in detail. Suitable structures are illustrated and described in our earlier patent publications GB 2129630 and EP0683925. 
     The first pair of IDC contacts  512 ,  514  lead to IDC contacts  546 ,  548  which project from beneath the base unit  500 . As shown in FIG. 23 they are connected to the IDC blades  550 ,  552  of a first MINI ROCKER™ connector  554  via wires  556 ,  558 , for receiving the wire pair leading to the further distribution point. MINI ROCKER™ connectors are single pair push-fit connectors for making connection to wire pairs as required. They are also shown, in a different context, in our earlier application published as GB 2293699. 
     The second pair of IDC contacts  518 ,  520  also lead to IDC contacts  560 ,  562  which project from beneath the base unit  500 . As shown in FIG. 22 these are connected to the IDC blades  564 ,  566  of a second MINI ROCKER™ connector  568  for receiving the wire pair from the exchange. 
     Thus, the base unit  500  is fitted in a distribution point and wire pairs to the exchange and a further distribution point fitted to the MINI ROCKER™ connectors. The configuration unit is then inserted in a first disposition, connecting the first and second IDC connectors  512 ,  514  and  518 , 520 , and linking the exchange pair to the further distribution point pair. 
     As and when a subscriber is to be connected, the configuration unit is removed and a subscriber pair connected to the blades  542 ,  544 . The configuration unit is then replaced in a reversed disposition, thereby connecting the second IDC connectors  518 ,  520  to the subscriber IDC connectors  506 ,  508 , linking the subscriber pair to the exchange pair and disconnecting the further distribution point pair. 
     If the subscriber needs to be disconnected, the configuration unit is removed, the subscriber pair removed, and the configuration unit replaced in its original orientation. The original network architecture is then restored with no loss of flexibility. 
     FIG. 23 shows an alternative wiring for the base unit  500 . Instead of connecting the first IDC contacts  560 ,  562  to the first MINI ROCKER™ and the second IDC contacts  546 , 548  to the second MINI ROCKER™, the A legs  546 ,  560  of the first and second IDC contacts are connected to the first MINI ROCKER™ and the B legs  548 ,  562  of the first and second IDC contacts are connected to the second MINI ROCKER™. Thus, to install the device the engineer fits the two A legs from the exchange and further distribution point pairs to the first MINI ROCKER™ and the B legs to the second MINI ROCKER™. In some circumstances that may be more convenient. The subsequent operation of the device is identical. 
     Finally, the fourth embodiment will be described with reference to FIGS. 24 to  27 . This comprises a 5-pair base unit  600  which is modular in form allowing one or more further 5-pair base units  602  etc to be attached at an end, thereby forming a  10 , 15 ,  20  etc pair module as desired. An end cap  604  is provided to close the attachment points at the end of the base unit  600 . A lid  605  is provided to seal the base unit against the environment when it has been installed. A base with a different number of pairs could alternatively be provided, but five is a convenient number. 
     Within each base unit  600 , five substantially identical points are provided. Each point includes a formation  606  for receiving a consumer plug  608 , adjacent a pair of sockets  610 ,  612  for the link pair and the exchange pair respectively. The sockets  610 ,  612  each contain a pair of connectors which are terminated via IDC blades at the rear on assembly or during installation with separate wire pairs. The pair to the exchange socket  612  leads back to the central exchange, possibly via other distribution points, and the pair to the link socket  610  leads onward to a further distribution point. If the unit  600  is installed at the last distribution point then the link socket  610  can be left unconnected. 
     A bridging link  614  fits into the sockets  610 ,  612  at the initial installation. This contains a pair of conductors which make contact with conductors in the link and exchange sockets via IDC connectors and thereby connect the exchange wire pair to the link wire pair as per FIG.  3 . 
     When a consumer is to be supplied with service, the consumer plug  608  is inserted. It is held in place by retention formations (not shown in FIG.  24 ). Until now the relevant formation  606  for accepting this has been left empty, allowing the service provider to minimize investment in the plant. The consumer plug  608  comprises a consumer socket  616  akin to the link and exchange sockets  610 ,  612  and a MINIROCKER™ type connector  618  as described above. Conductors within the consumer plug  608  make the necessary links between conductors in the consumer socket and  616  and the MINIROCKER™. A wire pair leading to the consumer premises is then connected to the MINIROCKER™. Finally, the bridging link  614  is removed from the link and exchange sockets  610 ,  612  and re-inserted in a 180° rotated orientation into the exchange socket  612  and the newly provided consumer socket  616 . Connection is therefore broken with subsequent distribution points and made with the consumer, as per FIG.  4 . To close the link socket  610  and seal it against the environment, a cap  620  is provided. 
     Earth connections within the base unit  600  are provided by an earth bar  622  which runs the length of the combined units  600 ,  602  etc. Within each 5-pair unit  600 , an earth strip  624  is provided which connects to the earth bar via an IDC connect  626  and provides the necessary earth conductors  628  appropriately positioned for access in the link and exchange sockets  610 ,  612 . This permits protection to be integrated into the bridging link  614  if desired. Also, other active devices could be incorporated into the bridging link  614  as envisaged in our earlier publication EP 0683925. Such active devices include line termination devices, remote identification devices, subscriber management devices, or any desired device. 
     FIG. 25 shows the electrical conductors within the unit. As shown, the consumer plug  608  is present and the bridging link  614  is seated in the link and exchange sockets  610 ,  612 . Either side of the earth bar  622  and earth strip  624  are two adjacent conductors  630 ,  632  for the exchange pair which have IDC blades  634 ,  636  at their lower extremities for connection to the wire pair and flat blades  638 ,  640  at their upper extremities for connection with the bridging link  614 . A similar pair of conductors  642 ,  644  are provided for the link socket  610  for connection with a wire pair leading to any further distribution point. 
     Within the bridging link  614  are a pair of conductors  646 ,  648 . Each extends from over the link socket  610  to over the exchange socket  612  and includes a pair of downwardly extending IDC blades  650 ,  652  projecting into the respective sockets and contacting with the conductors therein. Thus, with the bridging link in this position contact is made with between the exchange and link pairs. 
     Within the consumer plug  608 , a pair of contacts  654 ,  656  extend from the consumer socket  616  to a point beneath the MINIROCKER™. A pair of double-ended IDC blades  658 ,  660  lie within the MINIROCKER™ and connect at their lower end with the contacts  654 ,  656 . Their upper IDC contact is then available for connection to a wire pair leading to a consumer. 
     When the bridging link  614  is moved to the exchange socket  612  and the consumer socket  616 , the contacts  656 ,  648  therein will instead connect the exchange contacts  634 ,  636  and the consumer contacts  654 ,  656 . 
     FIG. 26 shows the unit with the bridging link  614  in the link and exchange sockets  610 ,  612 , partially cut away. This will therefore correspond to FIG. 3, the system as originally installed. The consumer plug  608  has not yet been fitted. A latch  660  on the base unit  600  engages with a tang  662  on the bridging link  614  to retain it in place. 
     FIG. 27 shows the unit with the consumer plug  608  present and the bridging link  614  in the exchange and consumer sockets  612 ,  616 . It is retained by a further latch  664  which engages with the tang  662 . The cap  620  is fitted in the link socket  610  and is retained by its own tang  668  which engages with the first latch  662 . The retention formations  670  for retaining the consumer plug  608  are visible. 
     The multiple IDC blades of the bridging link  614  could be made multiple-use, ie able to withstand repeated insertions. Alternatively, the bridging link could be an inexpensive disposable item intended to be replaced at each reconfiguration of the line. The part will also be lightweight, enabling engineers to carry a stock of such items to replace each time one has to be removed. 
     In all embodiments, it would be convenient to mark the visible surface of the configuration unit with a suitable indicia such as an arrow, to indicate to an engineer the configuration of the device. Surrounding parts can then be marked with appropriate indicia such as “SUBSCRIBER” so that an arrow pointing at SUBSCRIBER indicates that the device is disposed so as to break the wire pair and connect to a subscriber pair connected to that distribution point or elsewhere (as in point  110  of FIG.  1 ). In the fourth embodiment, the bridging link  614  includes an arrow device  672  (FIG. 27) which denotes the appropriate link. An asymmetric keying arrangement prevents the bridging link  614  from being inserted into the link socket  610  or the consumer socket  616  if it is incorrectly aligned. 
     It will be appreciated that many variations can be made to the above-described embodiments without departing from the scope of the present invention.