Patent GB-217981-A (GB)
IPC: H04M7/06
Abstract: 217,981. Siemens Bros. & Co., Ltd., Berry, J., and Peters, C. L. March 24, 1923. Automatic and semi-automatic exchange systems; metering.-In an exchange network in which the first three letters of the name of the wanted exchange are dialled to a register-controller, which translates them into the series of two or three digits necessary for routing the call to a wanted exchange, the first and second letters are registered on a 100-point switch and the second and third letters are registered on a second 100-point switch, the settings of these switches jointly determining the setting of a code selector, the contacts engaged by the wipers of which are jumpered over a distributing frame in a manner corresponding to the digits comprising the routing number. For example, if a subscriber in exchange " CITy " is required, a Strowger switch hereafter referred to as the AB recorder is set by the digits corresponding to the letters CI, and a second Strowger switch subsequently designated the BC recorder is set by digital equivalents of the letters IT. The code selector, which also comprises a 100-point Strowger switch, is first stepped up vertically by a counting switch to a level corresponding to the setting of the AB recorder, and is then rotated to a contact set in this level determined by the setting of the BC recorder. The contacts of the AB and BC recorders are jumpered to the contacts of the counting switch in such a manner as to utilize the hundred code selector contacts to the best advantage. If there are more than a hundred exchanges in the network, a further code selector can be added. The register-controller also comprises means for (1) steering the connection to manual or special operators' positions in response to particular digits, or if delay occurs between the dialling of the digits, (2) releasing the register-controller if no impulses are received by it, (3) giving the calling party a busy signal if dialling is begun before an idle register-controller is found, and (4) operating an attendants' alarm if the calling party delays dialling or a permanent loop develops across the calling line, if the calling party omits to hang up after the completion of the conversation, if delay occurs in the re-transmission of impulses by the register-controller. Other features of the system described are claimed in the divided Specifications 219,631, 221,459, and 221,460. Connection to idle register-controller. A calling line is extended over first and second preliminary selectors to an idle first selector trunk a, b, Fig. 1, the test circuit being completed over the test wire c and the wipers AS of an associated sequence switch in its normal position. The response of the line relay A energizes a relay V, which connects holding battery to the test wire c and closes a circuit CS, v3, cs for the sequence switch magnet SS. The magnet SS breaks its own circuit at contacts cs and on its relapse advances its wipers to their first position in which the stepping magnet TS of the registercontroller selector is energized and rotates its wipers tsa - - tsd. When an idle register-controller is engaged, a test relay P is energized over the test wiper tsc, opens the circuit of the stepping magnet TS, and short-circuits its righthand winding to mark the seized register-controller busy. An impulse relay AA is also energized over a circuit p3 tsb, za5, aa12, and closes a circuit for a relay VV, which energizes a relay D and also drives the sequence switch to its second position, in which a circuit is closed for an alarm lamp and for an alarm relay PL, which may control an alarm which operates after the relay PL ha.s been energized for a predetermined interval, to warn an attendant that the subscriber has delayed dialling or that a permanent loop has occurred. Registration of wanted number. The test relay P also closes a circuit over wiper tsa for an impulse-receiving relay A<1>, Fig. 2, at the register-controller, after which a slow-release relay V', Fig. 3, energizes the stepping magnet of a switch RS the function of which is to direct the series of incoming impulses to the appropriate register switches. In the first position of the switch RC a relay D' is energized over the wiper rca and an off-normal contact K12 of the AB recorder, and opens the circuit of the stepping magnet of the switch RC. The response of the relay D causes dialling tone to be transmitted over contact d3, and the subscriber commences to dial the wanted number. On the first relapse of the line relay A, the sequence switch is driven to its third position in which dialling tone is disconnected and the alarm relay and lamp PL deenergized. The first series of impulses are relayed at the contact a2 to the impulse receiving relay A<1> of the register-controller, where they are repeated over a circuit d12, a13, rcb, VMI, MA to the vertical magnet VMI of the AB recorder. On the cessation of the first impulse series the relay D1, which during impulse transmission is held over contacts a12, d12, relapses and re-energizes the stepping magnet of the switch RC which advances to its second position in which the relay D<1> is again energized over the wiper rca and an off-normal contact K22 of the BC recorder. The next series of impulses is repeated over the wiper rcb to the rotary magnet RM1 of the AB recorder and to the vertical magnet VM2 of the BC recorder, these magnets being connected in parallel. At the end of this impulse train the relay D<1> again relapses, the switch RC is driven to its third position, and when the third set of impulses is dialled it is repeated to the rotary magnet RM2 of the BC recorder. In the same manner the succeeding trains of impulses composing the numerical portion of the wanted number are directed in turn to the stepping magnets 30 - - 33 of the digit switches over the wiper rcb of the switch RC which advances a step after the transmission of each digit. Setting of the code selector according to the setting of the AB and BC recorders. This commences as soon as the BC recorder takes its first rotary step, the closure of the off-normal contacts W22, Fig. 2, completing the circuit of the start relay ST, Fig. 3, which energizes the stepping magnet of a switch R over a circuit 40, csc, c4, st1, r16. The switch R advances its wiper ra to the first earthed contact, and a moment later the interrupter 41, which lags a little behind the interrupter 40, energizes a relay AA<1>. The relay AA<1> energizes relay C, which locks up over contacts c1, t11, and opens the driving circuit of the switch R. The relav AA<1> now continues to be intermittently energized and de-energized by the interrupter 41, and at each relapse energizes the stepping magnet of a counting switch CS over contacts aa13, c2, and the vertical magnet VM3 of the code selector over a circuit c3, aa14, tcf. When the wiper csa of the counting switch CS reaches the terminal to which the bank contact engaged by the wiper AB of the AB recorder is jumpered, a circuit c5, csa, AB, tee is completed for a test relay T<1>, which is held energized for an interval over the interrupter 41, and at its armatures t11, t12 opens the circuits of the relays C, AA<1>. Relay T<1> also closes a circuit 41, t12 for the stepping magnet of a switch TC which advances to its first position, in which the wiper BC of the BC recorder is connected to the test relay T<1> over the wiper tcc. The relapse of the relay C completes a restoring circuit 42, csb, c2 for the counting switch CS, which in its normal position (over wiper csc) energizes the driving magnet of the switch R, which advances to its sixth position in which its wiper ra is earthed and the relays AA<1>, C energized as previously described, the relay C arresting the switch R and the relay AA<1> thereafter operating intermittently over the interrupter 41. The stepping magnet of the counting switch CS and the rotary magnet RM3 of the code selector are now energized simultaneously, the former over contact aa13 and the latter over the contact aa14 and the wiper bcf, until the counting switch wiper csa encounters the contact jumpered to the terminal engaged by the BC recorder, when the test relay T' pulls up, the relays C, AA<1> relapse, the counting switch CS is restored, and the switch TC is driven to its second position in which the test relay T<1> is connected over wiper tcc to the first wiper 1 of the code selector. Impulse sending operations of the register-controller. The counting switch CS now operates as previously described to engage the terminal marked by the wiper 1 of the code selector. During this operation the impulses which are received by the relay AA' are relayed over contacts aa12, za5 to the impulse relay AA of the first selector which is thereby set in accordance with the jumpering between the terminal engaged by the wiper 1 of the code selector and the counting switch CS. (The impulses received by the relay AA<1> during the setting of the code selector are not transmitted to the relay AA since in the normal and first positions of the switch TC the impulsing contact aa12 is shunted by the wiper tcb.) In a similar manner series of impulses corresponding to the jumpering of the other wipers 2, 3, 4 of the code selector and to the setting of the digit switches 30 - - 33 are sent out in succession, the switch TC advancing a step after each impulse series and connecting up the next wiper of the code selector or the next digit-switch wiper. The pause which occurs between the transmission of successive impulse series whilst the wiper ra of the switch R passes over 4 or 5 contacts to the next earthed contacts, is sufficiently long to permit a hunting operation to take place at a group selector over which the connection is extended. The contacts engaged by the wipers rce, tce of the switches RC, TC are so connected together that if the recording of a numerical digit lags,