US2249486A - Telephone system - Google Patents

Description

July 15, 1941. I. MOLNAR TELEPHONE SYSTEM 7 Filed Dec. 29, 1939 5 Sheets-Sheet 4 w e F 0 M M 7 8 Win n 4/..F 3 R WM m 8 0 C 4 W 4 C 4 0 5 L A 5 R M P. 5 R 1 8 n 0 4 5 L m 0 2 w 2 1Q; 3 3 2 V W INVENTOR Imre Mal/'70!" BY ATTORNEYS Patented July 15, 1941 TELEPHONE SYSTEM Imre Molnar, Chicago, Ill., assignor to Associated Electric Laboratories, Inc., Chicago, Ill., a corporation of Delaware Application December 29, 1939, Serial No. 311,546

57 Claims.

The present invention relates to telephone systems and more particularly to improvements in apparatus for handling branch exchange calls of a special character.

As explained in Patent No. 1,816,634, Carpenter et al., granted July 28, 1931, and Patent No. 1,841,093, Dahl, granted January 12, 1932, in certain' branch exchange installations a large part of the incoming calls are of a special character. For example, in large department stores a major portion of the incoming calls are for the purpose of placing orders or represent requests for information concerning the price of the merchandise on sale. In order more expeditiously to handle the calls incoming to a branch exchange of this type it is desirable to segregate the calls of special character from the other calls and to route the calls of special character to special informa tion or order operators positions, which positions are staffed with attendants qualified to dispatch the desired information. In the two patents cited above, apparatus is provided for the general purpose just mentioned, the arrangement being such that all of the calls of special character are first stored in a call storage circuit and are then released from storage to the special operators positions in the same order as they are stored. This arrangement not only requires an extremely complicated and extensive switching arrangement in association with the special operators positions, but is open to the objection that the calls are delayed somewhat due to the extensive switching operations required to first store the calls and then release the calls from storage.

It is an object of the present invention, there- 'fore, to provide in a telephone system improved special call handling facilities of the character described which are of simple and economical arrangement, are positive and reliable in operation and are so arranged that the special calls are normally routed directly to the special operators positions so long as any of the special operators positions are idle.

It is another object of the invention to provide improved special call handling facilities of the character described wherein provisions are made for storing the special calls only when the number of special calls existing at any one time exceeds the call handling capacity of the special operators positions.

It is a further object of the invention to provide improved special call handling facilities of the character described wherein the call storage circuit is so arranged that the excess stored calls are released from storage and routed to the special operators positions in the same order as they were stored.

It is another object of the invention to provide an improved call storage arrangement wherein exceedingly simple provisions are made for positively preventing undue delay in releasing calls from storage and for normally preventing excess calls from obtaining preferred storage positions.

It is a further object of the invention to provide a call storage circuit of the character described which is so arranged that excess calls may be permitted to obtain preferred storage positions, whereby under certain conditions of heavy trafiic all of the available call storage positions of the circuit may be utilized.

It is still another object of the invention to provide in a telephone system, improved special call handling facilities of the character described wherein provisions are made for readily transferring the calls of special character from the special operators positions to the regular branch exchange switchboard and for routing calls directly from the special operators positions to the branch exchange switchboard.

It is astill further object of the invention to provide in a telephone system including special call handling facilities of the character described, an improved arrangement whereby all of the special call trunks, the call storage circuit and the special operators positions may be supervised from a supervisory operators position and the call storage apparatus may be controlled from the supervisory operators position.

In the illustrated embodiment of the invention, there is provided atelephone system which comprises a central exchange and a branch exchange area including regular'branch exchange facilities. These facilities comprise the usual branch exchange switchboard at which are terminated a plurality of trunks which extend to switching equipment in the central exchange. The system further comprises additional apparatus which is adapted to handle the calls of special character routed from the central exchange to the branch exchange area. This additional apparatus comprises a plurality of special operators positions and'a plurality of special call trunks which extend from the central exchange and terminate in the branch exchange area in trunk circuits, each of which includes a position finder having access to all of the special operators positions. The arrangement of the trunk circuit apparatus is suchthat calls originating on the associated trunks in the central exchange are automatically routed through the associated position finders directly to idle ones of the special operators positions so long as any of these positions are idle. For the purpose of storing excess or overflow calls until such time as special operators positions are available, thereis provided a call storage circuit which is commonly associated with the various trunk circuits and includes a call storage position distributor and call storage release means. In order to permit the transfer of special calls from the special operators positions to the regular branch exchange switchboard, a plurality of transfer trunks are provided, which extend from the trunk circuits just mentioned to the branch exchange operator's switchboard. The transfer trunks are utilized solely to transfer incoming special calls to the branch exchange operators switchboard, an additional group of trunks being provided for enabling the special operators to extend calls from their respective positions to the regular branch exchange switchboard. More specifically, the additional trunks, just mentioned, individually terminate in position finder switches which have access to the special operators positions and have commonly associated therewith a distributor which functions to allot the position finders and associated trunks for use in a predetermined order.

The arrangement of the call storage circuit and of the associated trunk circuits individual to the special call trunks is such that stored calls are released from storage in the same order as they are stored. More particularly, each.of the trunk circuits is provided with a storage position finder having positions individually corresponding to the storage positions of the storage position distributor and the call release positions of the storage release means. The arrangement is such that the storage finders are operated in response to calls initiated on the associated trunks when all of the special operators positions are busy, means controlled by the storage distributor being provided for stopping the storage finders in different positions whereby the excess calls are stored in a predetermined order. Additional apparatus controlled Jointly by the storage release means and the storage position finders and operative in accordance with the settings of the storage finders, are provided for routing the stored calls to the special operators positions in the same predetermined order as the special operators positions are released or become idle. In order to prevent any unnecessary elapse of time in releasing calls from storage, control apparatus is provided for preventing the storage release means from operating through a position occupied by the position of the storage position distributor. Additional control apparatus is provided for normally preventing the storage position distributor from operating through a position occupied by the storage release means, thereby to prevent later initiated special calls from obtaining preferred storage positions. The arrangement is such that the last-mentioned control apparatus may be rendered inactive, whereby storage positions of the storage distributor which correspond to abandoned stored calls may be utilized in storing additional calls. More specifically, the last-mentioned control apparatus is under the control of a supervisory operator whose function it is to maintain supervision of the various special operators positions and the special call trunks having access to these positions. To this end. various supervisory lamps are provided at the supervisory operators position and Provibranch exchange area 20 there are provided a plurality of branch exchange trunks, one of sions are made whereby the supervisory operator may monitor any connection established to any one of the special operators positions. Among the supervisory lamps provided at the supervisory operator's position are included a group of call storage lamps which are individual to the several special call trunks, the arrangement being such that each of these lamps is energized when a call, present on the associated trunk, is placed in storage. Further, the control arrangement for the call storage lamps is suchthat each lamp is deenergized when a call stored on the associated trunk is abandoned prior to its release from storage. By virtue of this arrangement, the

1 supervisory operator may maintain a close check upon the number of calls in storage and ascertain the advisability of utilizing vacated call storage positions of the call storage distributor to store additional calls.

Further features of the invention pertain to the particular arrangement of the circuit elements whereby the above-outlined and additional operating features are attained.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention, both as to its organization and method of operation, together with further objects and advantages thereof will best be understood by reference to the specification taken in connection with the accompanying drawings in which Figure 1 schematically illustrates a telephone system having incorporated therein the features of the invention as briefly outlined above; Fig. 2 illustrates the manner of assembling the remaining figures of the drawings to form a unified system; and Figs. 3 to 6, inclusive, illustrate the details 1of the apparatus schematically shown in Referring now more particularly. to Fig. 1 of the drawings, the telephone system there illustrated comprises a central exchange l0 and a branch exchange area' 20 within which are located the substations of a department store, or the like. The central exchange l0 may be of any desired type; that is, it may be of the manual type, in which case, the subscribers and trunk lines extending thereto are terminated in line multiples at the operators switchboard in the usual manner. Alternatively, the exchange ll may be of any desired automatic type, in which case, connections are established between the lines extending thereto through the provision of dial controlled automatic switching apparatus. This exchange is arranged to serve a large number of central omce subscribers lines, one of which is indicated at H as extending to the central oflice subscriber's substation A. For the purpose of routing regular substation-to-substation calls between the central oiiice and the which is indicated at I2. This trunk has a trunk circuit l3 of conventional arrangement associated therewith and terminates at a jack M which is provided at one of the operators positions forming a part of the branch exchange operator's switchboard. This switchboard is provided for the purpose of serving the regular branch exchange substations located within the area 2|,

- one such substation B being connected to a substation line I! which terminates at the branch exchange switchboard in a jack l1 and has associated therewith a line circuit Ii through operation of which calls involving the line l5 may be supervised. 4

In order to handle calls of special character routed from the central oflice subscribers substations through the central exchange I 0 to the branch exchange area 20, a plurality of special call trunks, one of which is indicated at l8, are provided. Assuming that the central exchange In is of the manual type, these trunks extend from the operators switchboard in the central exchange I 0 to the branch area 20 where they terminate in trunk circuits individual thereto. These trunk circuits have access to a group of special operators positions. In the case under consideration wherein it is assumed, for purposes of explanation, that the branch exchange area 20 constitutes a department store or other merchandise establishment, the special operators positions may be provided for the purpose of taking orders from the central office subscribers. For convenience in describing the apparatus, the special call trunks will be referred to hereinafter as order trunks, the trunk circuits associated therewith will be referred to as order trunk circuits, and the special operators positions will be referred to as order operators positions. More specifically, the order trunk l8 terminates in the branch exchange area 20 in an order trunk circuit I 9 which has access to a group of order operators positions including the position 2|. Under certain circumstances and, more particularly, when all of the order operators positions are not staifed, the volume of trafiic over the order trunks may be in excess of the call handling capacity of those order operators positions which are attended. In order to hold such excess calls until such time as an order operators position is released, there is provided, in common association with the several order trunk circuits, a call storag circuit 3| which functions to store the excess calls in the order of their initiation and to release the stored calls from storage in the same order, as the order operators positions become idle. For the purpose of enabling the order operators to transfer calls from their positions to the branch exchange switchboard, whereby they may be extended to the regular branch exchange substations, there are provided a group of transfer trunks, one of which is indicated at 22 as extending from the order trunk circuit l9 to a jack 23 located at the branch exchange operators switchboard. This group of trunks can only be used for transfer purposes. Accordingly, additional means comprising a second group of trunks including the trunk 28 is provided for enabling the order operators to route calls directly from their positions to the branch exchange switchboard. More specifically, these additional trunks terminate in position finders which have access to the various order operators positions and have associated therewith a position finder distributor 30 which functions to allot the additional trunks and associated position finders for use in a predetermined order. Thus, the trunk 26 terminates at the branch exchange switchboard in a jack 28 and extends to a position finder 29 having access to all of the order operators. positions. For the purpose of supervising calls routed by way of the order trunks to the order operators positions there is provided a supervisory operators position 32 at which are located signal lamps for indicating whether or not the order operators positions are staffed and, if staffed, whether idle or busy, and also for identifying those of the order trunks which are occupied with calls in storage.

Neglecting for the present the particular arrangement 0f the circuit elements embodied in the apparatus schematically illustrated in Fig. 1 and considering the operation of the system generally, it will be apparent that interexchange traific between the central oflice subscribers substations and the regular-substations provided in thebranch exchange area 20 are handled by the regular branch exchange facilities including the branch exchang operators switchboard and the group of trunks of which the trunk l2 forms a part. To thi end, the branch exchange operators switchboard is assigned a particular directory number which is different from the directory number assigned to the order operators positions. By virtue of this directory numbering scheme the special or order trunk calls may be segregated in the central exchange and routed by way of the order trunks to idle ones of the order operators positions. For example, a call routed over th order trunk l8 may, through operation of the order trunk circuit Ill, be routed to the order operators position 2|. If the order operator attending this position is unable to give the calling subscriber the desired information, she may cause the call to b .transferred to one of the regular substations provided in the branch exchange area 20 by operating a transfer key located at her position, thereby to signal over the transfer trunk 22 the branch exchange operator attending the position at which the trunk 22 is terminated. The branch exchange operator may, in turn, route the call to the desired substation, such, for example, as the substation B. After a call transfer of this character is made the order operator attending the position 2| may remain connected to the established three-way connection or may retire from the connection and release her position for utilization in the handling of additional calls. If an operator attending one of the order operators positions, such, for example, as the position 2|, finds it necessary in handling an inquiry to look up certain information and then call a central ofiice subscriber, she may secure the desired connection by seizing one of the trunks assigned for use by the position finder distributor 30, such, for example, as the trunk 26, thereby to route a connection from her position to a position at the branch exchange switchboard. From this latter position the call may be routed over one of the regular branch exchange trunks and through the central exchange ID to the desired substation. In a similar manner the order operators may route calls directly from their positions to the regular substations located in th branch exchange area, such calls being handled by the operator or operators attending the branch exchange switchboard. In the event all of the order operators positions become busy at the same time and special calls routed over the order trunks continue to arrive, operation of the call storage circuit 3| is initiated whereby the excess calls are stored in the order of their initiation. As th order operators positions are thereafter released and rendered available for use in handling other calls, the call storage circuit 3| in cooperation with the associated trunk circuits functions to release the stored calls from storage in the same order as they are stored. Supervision of the order operators positions and of the special calls handled at these positions is under the control of a super. visory operator attending the position 32.

' I" and a plurality of associated control relays and control circuits. The switches 360 and 400 are of the well-known rotary type and may be of any desired commercial construction. The number or contact points provided in the position finder switch 400 is determined by the number of available order operators positions, each setting of this switch being individual to a particular order operator's position. Similarly, the number of contact points provided in the storage position finder switch 360 is determined by the number of storage positions available in the call storage circuit 2|. In the arrangement illustrated, twenty-four call storage positions ar available in this circuit and hence twenty-five sets of contact points are provided in the rotary switch 360, the first set of contact points being reserved as the normal or home position of this switch. The control equipment associated with the two switches 360 and 400 comprises a line relay R300 which is normally bridged across the conductors of the order trunk I8 in series with a condenser Ill and is arranged to operate when energized with either alternating or direct current. This equipment further comprises a slow-to-operate position finder start relay Bill), a pair of call storage control relays R320 and R330, a combined cell transfer and trunk release relay R340 which is provided with two operating positions in addition to its normally released position, and a combined finder stop and line switching relay R250.

The apparatus provided at the order operator's position 2| comprises an induction coil I which is connected to a pair of talking conductors C492 and C493, these conductors being terminated in corresponding sets or contacts in the position finder switches individual to the various trunk circuits. This induction coil has connected thereto transmitter and receiver jacks 4|! and 4, respectively, which are arranged to receive the contacts of a multiple plug 2'', The contacts of this plug are connected in the usual manner to a transmitter 4H and a receiver 2 forming an operator's head set. There is also provided at the operators position 2| a relay R00, which is operative to indicate that the position is staffed, and a slow-to-operate control relay R440. The latter relay is arranged to control the energization of a call signallamp 423 and 'to perform other control operations described hereinafter. The control equipment provided at the order operators' position III also includes a combined call transfer and trunk circuit release key 6 and a branch exchange call key 420, the first of these keys being operative to control the transfer of calls from the position 2| to the branch exchang switchboard and to control the release of trunk circuits which are operated when calls are routed by way thereof to the position 2|. The key 420, on th other hand, is provided for the purpose of routing calls from the order operator's position 2| directly to the branch exchange switchboard.

As illustrated in the right-hand portion of Fig. 4, the position finder 29, which is individual to the trunk 26 extending to the branch exchange switchboard. comprises a finder switch 450 of the well-known rotary type and a line switching relay R480. The number of contact points provided in the finder switch "I is determined by the number of associated order operators positions, one set of contact points being'reserved for each of the order operators positions to which it has access. Operation of this position finder and of-the other finders individually associated with the other trunks extending to the branch exchange switchboard is under the control of the position finder distributor 30 which is illustrated in Fig. 6 as comprising a distributor switch 640, also of the well-known rotary type, and having positions corresponding to the number of position finders available. This distributor also includes a plurality of control relays which may be identified as a slow-to-operate start relay RBHI, a pulsing relay R830, a relay R820 for controlling the line switching relays of the respective associated position finders, and a slowto-release relay R600 which is operative to delay the trunk hunting operation of the distributor switch 640 for a short time interval after a previously selected position finder switch is operated to seize a calling one or the order operators positions.

As pointed out previously, the apparatus provided at one of the branch exchange operators positions forming a part of the branch exchange switchboard comprises the jacks H, 28, I4 and 23 at which the lines ll, 26, I2 and 22, respectively terminate. These lines have individually associated therewith call signal lamps 668, 663, 665 and 653, respectively. There is also provided at this branch exchange operator's position an operator's cord circuit 860 which may be of conventional arrangement. This cord circuit is connected to call and answer plugs 652 and Gil, respectively, and includes a transmitter 610 and a receiver ill.

The call storage circuit 3| is illustrated in Fig. 5 as comprising a call storage distributor switch 500 and a call release switch 5! each of which is of the well-known rotary type and includes twenty-five sets of contact points respectively representing twenty-four difi'erent call storage positions and a blank or unused position. The operation of these switches is under the control of associated relay equipment which comprises a call storagestart relay R540, a call storage stop relay R530. and a pulsing relay network for the rotary switch H0 which includes the relay R520 and the slow-to-release relay R510. A second slow-to-operatepulsing relay R560 is provided for controlling the operation of the distributor switch 500. The relay equipment also includes a stop relay R550 which functions to prevent the rotary switch Elli from operating to a storage position in advance of that occupied by the distributor switch 500 all in the manner more fully explained hereinafter. For the purpose of indicating an all-busy condition of the order trunks, there is provided an all-trunk's-busy meter 522.

The apparatus provided at the supervisory operator's position 22 comprises a plurality of jacks at which are terminated trunk lines bridged across the talking conductors provided in the various order operators positions. Thus, a jack I is provided which is connected to the conductors C482 and C493 constituting the talking conductors provided at the order operator's position 2|. There are also provided at the supervisory operators position 32 a plurality of signal lamps individual to the order operators positions and to the order trunks which enable the supervisory operator to check at all times the condi-- tion of the trunks and of the order operators positions. Thus, a position lamp 425 is provided which is individual to the order operator's position 2| and which, when energized, indicates that this order operators position is attended. A second lamp 424 individual to the order operator's position 2| is also provided which, when energized, indicates that the associated position is busy. A third signal lamp 426 is provided which is individual to the order trunk l8 and functions, when energized, to indicate that the associated order trunk is occupied with a call which has been placed in storage. In order to enable the supervisory operator to control the call storage circuit 3| in accordance with the conditions indicated by the energized and deenergized conditions of the associated trunk call storage lamps, there are provided two keys 42! and 422, the last of which is operative to render the call storage circuit 3| totally inactive. The key 42!, on the other hand, is provided for the purpose of enabling the storage distributor switch 500 to be advanced through a position occupied by the call release switch 5lll, thereby to permit those call storage positions in the switch 500 which have the connection has been been vacated through the abandonment of stored calls to be filled up with additional incoming calls.

Traflic between central office and branch exchange switchboard Referring now more particularly to the operation of the apparatus illustrated in Figs. 3 to 6, inclusive, if a call routed over one of the central oflice subscribers lines, such, for example, as the line II, to an operators position in the central oflice I0 is to be extended to a substation line accessible to the branch exchange switchboard, the central oflice operator handling the call may seize the trunk I2 and, by operation of the ringing key embodied in her cord circuit, project ringing current over this trunk for the purpose of energizing an alternating current relay bridged across the conductor of this line and included in the trunk circuit l3. The resulting operation of this alternating current relay causes the energization of the call lamp 665 individual to the trunk l2. The branch exchange operator, upon observing the lighted condition of this lamp, may answer the call by inserting the plug 66l in the jack I 4. In response to this operation, a talking circuit is completed between the calling subscriber's substation and the branch exchange operators head set, whereby the operator may converse with the calling subscriber and obtain the identity of the desired branch exchange substation. When the plug 66! is inserted in the jack l4, ground potential is impressed upon the ring contact of the jack l4 to cause the energization and operation of one of the relays included in the trunk circuit apparatus I3. The resulting operation of this relay causes the deenergization of the call lamp 6B5in the usual manner. When the plug GBI is inserted in the jack l4, a direct current bridge is also established between the tip and sleeve contacts of this jack, thereby to cause the operation of a supervisory relay-embodied in the cord circuit in use by the operator handling the call in the central oifice I0. Assuming that the substation B is desired by the calling central oflice subscriber, the branch ex- .change operator may extend the connection to the desired substation by inserting the call plug 662 in the jack I! and operating the ringing key of the cord circuit 660 to cause ringing current to be projected over the line l5 and through the windings of the ringer conventionally provided at the substation B. When the call is answered at the called substation, the branch exchange operator may retire from the connection and rely upon the supervisory lamps embodied in the cord circuit 680 to indicate when the connection is ready to be released. When either of the two lamps individual to the calling and called ends of the connection is illuminated, indicating that released at one end thereof, the branch exchange operator may clear out the connection. For example, if the called party at the substation B hangs up prior to the release of the connection at the calling end thereof the supervisory lamp of the cord circuit 660 individual to the called is energized to indicate to the branch exchange may now clear out the connection by withdrawing the plugs 66l and 662 from the jacks l4 and II, respectively. In response to this operation, the trunk circuit l3 and the line circuit l6 are restored to normal in the usual manner and the bridge circuit established across the conductors of the trunk line I2 is opened to cause the energization of the disconnect lamp associated with the trunk line I! and embodied in the cord circuit in use at the operator's position in the central ofllce l0. Upon observing the lighted condition of this lamp, the operator handling the call at the central oflice may clear out the connection in the usual manner.

In the event thecall is cleared out at the subresponse to this operation a disconnect signal is transmitted over the trunk I2 to the cord circuit 660 to cause the energization of the supervisory lamp in the cord 0 *uit 660 which is individual to the calling end of the connection. Energization of this lamp serves to inform the branch exchange operator that the connection has beenreleased at the calling end thereof and may be cleared out at her switchboard. To clear out the connection, the operator withdraws the plugs 6! and 662 from the jacks l4 and II, respectively, whereby the trunk circuit I3 and the line circuit l6 are restored to normal in the usual manner.

The trunk l2 and the other similar trunks may also be used in routing calls from the branch exchange switchboard to the subscribers lines terminating at the central ofiice I 0. For examring contact of the jack I"! to complete a circuit for energizing the signal lamp cut-ofi relay conventionally embodied in the line circuit I 6'.

The resulting operation of this relay causes the deenergization of the call lamp 666. Upon ascertaining that a central oflice call has been initiated at the substation B, the P. B. X. operator may forward the connection to an operators position in the central ofilce I by inserting the plug 652 in the jack l4 and operating the ringing key embodied in the cord circuit 660 to project ringing current over the trunk line l2. The resulting operation of the signal device or devices individual to this trunk line and provided at the operators switchboard in the central oflice l0 serves to inform one or more of the central oflice operators that a call is present on the trunk, line l2 which should be answered. Upon answering the call the central oilice operator handling the call may converse with the party at the substation B and ascertain the substation desired by the calling party, following which may set up the desired connection in the manner conventionally followed in manual oflice practice. After the connection has been established, the supervision and release thereof are exactly the same as set forth above with reference to a call routed from a central ofllce subscribers substation to one of the branch exchange telephone stations.

Central oflice call to order operators position Each of the order operators, when on duty, maintains her telephone set connected to the substation circuit apparatus provided at her position. For example, when an operator is on duty at the order operators position 2| the terminals of the multiple plug H2 and terminating the cords respectively extending to the transmitter 4H and the receiver 2, are maintained inserted in the jacks M3 and M4, respectively, so that the transmitter 4| I is bridged across one winding of the induction coil 5 in series with a coupling condenser and the receiver 4 2 is bridged across a portion of the other induction coil winding in series with another coupling condenser. With the transmitter 4 connected to the terminals of the jack 3, a circuit extending through the plug and jack contacts and the transmitter 4 is completed for energizing the relay R430 and for supplying energizing current to the transmitter. With the relay R430 in its operated position, a battery marking path is completed, at RA43I, for identifying the operators position 2| as idle in the bank contacts of all of the position finders having access thereto. As explained more in detail hereinafter when the position is occupied with a call this idle marking is removed and a busy ground marking is substituted therefor. Thus, under normal conditions incoming order trunk calls are being handled, certain of the order operators positions are marked as idle and others are marked as busy in the bank contacts of the position finders. With the relay R430 operated, a circuit extending through RA433 is completed for energizing the position lamp 425 individual to the order operators position 2| and located at the supervisory operators position 32, thus indicating to the supervisory operator that the order operators position 2| is attended.

Assuming that certain of the order operators positions are conditioned to receive incoming calls, and further that the trunk line I8 is seized at the central oifice and ringing current is projected thereover, the relay R300 is energized by the ringing current traversing its winding, the resistor 3|5 and the condenser 3H in series,

Upon operating, the relayv R300 completes, at RA30I, a circuit for energizing the relay R3l0, this circuit extending from ground by way of RA30|, RA344, RA32| and the winding of R3|0 to battery. At RA302, the relay R300 prepares a circuit, now open at RA54|, for energizing the upper winding of R320. At RA303, the relay R300 prepares a holding circuit for the relay R330. The relay R3|0 operates after an interval to open, at RA3|4, the prepared operating circuit for R320; to prepare at RA3I3, a test circuit including the lower winding of R350; and to complete, at RA3I2, a circuit extending through RA353 and over C311 forenergizing the magnet 403 of the position finder switch 400. At RA3I3, the relay R3|0 also completes a priming circuit for the relay R350, this circuit extending through the resistor 358 and the upper winding of R350 to battery. The resistance of this priming circuit is such that R350 does not operate when it is completed. At RA3| the relay R3|0 connects the winding of the relay R300 directly across the line conductors of the trunk line l8, thereby to cause the operation of an answer lamp embodied in the cord circuit being used by the calling operator in the central ofllce I0 and to establish a loop circuit including the central exchange battery over which the line relay R300 is held energized.

Due to the circuit interrupting action of the armature 0 carried by the magnet 409, the position finder switch 400 operates buzzer fashion so that the wipers thereof are advanced step by step until the contacts corresponding to the first idle order operators position are selected. During this operation of the switch 400 the lower winding of the relay R350 is short circuited so long as the test wiper 401 is passing over con tacts corresponding to busy order operators positions. Assuming that the order operator's position 2| is the first idle position available, operation of the switch 400 is arrested when the wipers of this switch are advanced to the position corresponding to this order operators position. More specifically, when the test wiper 401 engages the associated test contact individual to the position 2|, the above-mentioned test circuit is completed, this circuit extending from ground by way of RA3I3, the lower winding of R350, C318, the wiper 401, RA43| and the winding of R440 to battery. When its lower winding is energized over this circuit the relay R350 first operates to complete, at the X contacts associated with RA354, an obvious path for shortcircuiting the resistor 358, whereby its upper winding is fully energized. Following this operation, the relay R350 fully operates to open, at RA353, the above-traced operating circuit for the magnet 403, thereby to arrest operation of the switch 400 with the wipers of this switch standing on the contacts terminating the conductors extending to the substation apparatus provided at the order operators position 2|. At RA35| and RA352, the relay R350 connects the conductors of the trunk line l8 through the line wipers 405 and 400 of the line switch 400 to the line terminals of the induction coil 45|, thus completing a talking circuit between the calling central oifice subscriber's substation and the telephone set in use by the operator attending the position 2|. At RA355, the relay R350 prepares a circuit traced hereinafter for energizing the combined call transfer and trunk release relay R340. At RA355, the relay R350 opens a point in the prepared holding circuit for R330. At

contacts associated with RA344 RA351, the relay R350 removes ground potential from the marking wiper 368 of the storage posithe circuit. for energizing the busy lamp 424 provided at the supervisory operators position 32.

' Thus, the trunk circuit apparatus I9 is fully retion 2| ground potential as connected through the lower winding of R350 and over C318 to the wiper 401 is impressed upon the test contacts of all of the other position finder switches which correspond to theorder operators position 2|, thus identifying this order operators position as busy in the contacts of the other'position finder switches.

As indicated above, the slow-to-operate relay R440 is energized in series with the lower winding of the relay R350 immediately the order operators position 2| is selected by the position finder switch 400. The relay R440 operates after an interval to complete, at RA442, an obvious circuit for energizing the call signal lamp 423, thereby to indicate to the operator attending the position 2| that an incoming call should be answered. At RA442, the relay R440 also opens one of the multiple paths over which ground potential is normally impressed upon the storage start conductor 0483. At RA443, the relay R440 completes an obvious circuit for energizing the busy lamp 424 provided at the supervisory operators position 32 and individual to the order operator's position 2 l.

Following operation of the relay R350 to establish a talking circuit between the calling central ofllce subscribers substation and the operators position 2|, the order operator attending this position may converse with the calling subscriber and give the calling subscriber the information desired. In order to initiate the release of the connection after the conversation is terminated, the operator attending the position 2| momentarily actuates the release key M6 to the offnormal position required to cause engagement of the springs 8. When these contact springs are engaged a circuit is completed for partially eneregizing the call transfer and trunk release relay R340, this circuit extending from ground by way of the resistor 4| 9, the springs M, the wiper 408, 0319, RA355 and the winding of R340 to battery. When energized over this circuit the relay R340 partially operates to open the closed without closing the make contacts associated with this armature. As a result, the above-traced operating circuit for the relay R3|0 is interrupted and this relay restores to open the holding circuit for R350; to open a further point in the operating circuit for the driving magnet 409; and to disconnect the winding of the line relay R300 from across the conductors of the trunk line l8, thereby to cause the energization of a disconnect signal lamp provided in the cord circuit in use in the central oifice l0 in the usual manner. The relays R300, R350 and R440 now restore. Shortly thereafter and when the call transfer'and trunk release key M6 is released and allowed to return to its normal position, the springs 8 are opened to open the circuit for partially energizing the transfer and release relay R340, causing this relay to restore. The relay R440, upon restoring opens, at RA442, the circuit for energizing the call lamp 423; prepares, at RA44I, the path for impressing ground potential upon the distributor start conductor C480; completes, at RA442, the multiple path, individual to the position 2|, over which ground potential is normally impressed upon the conductor C483; and opens, at RA443,

. operating circuit for the relay R3l0.

stored to normal and the order operators position 2| is again identified as idle in the bank contacts of the various position finders having access thereto. When the central oflice operator handling the call observes the lighted condition If the connection routed over the trunk line 8 to the order operators position 2| is released at the operators position in the central ofiice |0 prior to actuation of the transfer and M6 in the manner set forth in the paragraph, the relay R300 restores'to open the The relay R3I0, upon restoring, causes the release of the relays R350 and R440 in the manner previously explained. Thus, in the case where the connection is cleared out at the operators position in the central oflice l0, the trunk circuit l9 and the operators position circuit are fully released without any operation on the part of the order operator attending the position 2|.

Transfer of order trunk call to branch exchange switchboard In the event the order operator attending the position 2| finds it necessary to converse with a party located at one of the branch exchange substations in order to obtain the information desired by the calling subscriber, or to connect the calling subscriber directly to one of the branch exchange substations, she may route the call to the branch exchange switchboard by operating the transfer and release key 6 to the off-normal position required to cause engagement of the contact springs 4". In response to this operation the relay R340 is energized over a circuit from which the resistor M9 is excluded and, accordingly, is caused fully to operate. While assuming its fully operated position, the relay R340 completes, at RA344, an obvious holding circuit for the relay R3l0; initially completed operating circuit for the latter relay. At RA342 and RA343, the relay R340 opens the established talking circuit extending between the calling subscribers substation and the'substation equipment provided at the order operators position 2|. At RA34| the relay R340 completes a circuit for energizing the signal lamp 653 provided at' the branch exchange switchboard, this circuit extending from ground by way of RA34I, C345, the jack-springs 854 and the filament of the lamp 653 to battery. The energization of the lamp 653 serves to inform the branch exchange operator that a call is present on the transfer trunk 22 which should be answered. To answer the call the branch exchange operator may insert the answer plug 06| of the cord circuit 660 in the jack 23, thereby to comat the same time opening the Assuming, for example, that the substation B is desired by the order operator, the branch exchange operator may route the connection to this substation by inserting the call plug 662 in the Jack I1 and operating. the ringing key provided in the cord circuit 660 to cause ringing current to be projected over the line l5 for the purpose of energizing the ringer or signal device provided at the substation B. When the call is answered at the substation B, the desired talking circuit may be established through the operators cord circuit 660 between this substation and the substation apparatus provided at the order op erators position 2|. With the apparatus in this condition the operator attending the position 2| may converse with the answering party at the substation B to obtain the desired information, and during the course of the conversation the calling central oflice subscriber is excluded from the connection. If the operator attending the position 2| desires, she may establish a threeway talking circuit between her substation, the

central ofiice subscriber substation and the substation E. To this end, the transfer and release key 6 is restored to its normal position. In response to this operation the transfer and release relay R340 is released to open the completed holding circuit for the relay R310 and torecomplete the operating circuit for this relay. At RA342 and RA343, the relay R340 connects the conductors of the order trunk l8 to the talking conductors of the transfer trunk 22, thereby to establish a talking circuit between her station, the calling central oflice substation and the substation B. Upon restoring, the relay R340 also opens, at RA34I, a further point in the previously traced circuit for energizing the signal lamp 653. After the connection is established between the substation B and the substation of the calling central office subscriber in the manner just explained the operator attending the order operators position 2| may return from the connection and release the trunk circuit 19 and the position circuit individual to the position 2| by operating the transfer and release key 416 to the position required to cause engagement of the contact springs 418. The manner in which the trunk circuit apparatus l9 and the order operators position circuit are released in response to operation of the transfer and release key 416 is exactly the same as described previously. Following the release of this apparatus, supervision of the call as extended through the operators cord circuit 660 to the substation B is under the control of the branch exchange operator, the supervisory lamps provided in the cord circuit 660 being utilized to indicate when the connection is no longer desired. In this regard it is pointed out that an auxiliary direct current bridge is established in the operators cord circuit 660 between the line conductors of the order trunk 18 when the answer plug 681 is inserted in the jack 23 and the transfer and release relay R340 is restored to normal. Thus, energization of the disconnect lamp associated with the trunk 13 and provided in the cord circuit in use in the central ofllce I0 is under the control of the branch exchange operator. More particularly, if the branch exchange operator receives a disconnect signal caused by release of the connection at the substation B, she may clear out the connection by withdrawing the call and answer plugs 662 and GM, respectively, from the jacks l1 and 23, respectively. In response to this operation the established direct current bridge across the conductors of the trunk I0 is interrupted causing the energization of the disconnect lamp provided in thecord circuit in use in the central oflice I0. The central omce operator may then clear out the connection in the usual manner. If the central ofllce subscriber is the first to abandon the connection, the central office operator may clear out the connection in the usual manner and in so doing opens the loop circuit extending by way of the trunk 18 and the transfer trunk 22 to the operator's cord circuit 660, thus causing the energization of the disconnect lamp provided in this cord circuit. As a consequence, the branch exchange operator is informed that the connection is ready for release and may clear out the connection by withdrawing the plugs 662 and 661 from the jacks l1 and 23, respectively.

Call from order operators position to branch exchange switchboard If for any reason the operator attending the order operators position 2| finds it necessary to obtain information from one of the clerks or employees normally attending one of the branch exchange substations, she may cause a connection to be routed to the branch exchange switchboard by operating the call key 4220 to its off-normal position. In response to this operation the contact spring-s 435 are engaged to prepare a circuit, traced hereinafter, for energizing the relay R440; the contact springs 433 and 434 are disengaged to open the associated multiple path over which ground potential is normally impressed upon the conductor C403; and the springs 433 and 432 are engaged to complete a circuit for energizing the distributor start relay R6l0. This circuit extends from ground by way of the springs 433 and 432, RA44I, C480, the winding of R6l0, RAGI3, the armature 652 and the winding of the magnet 65l to battery. Due to the relatively high resistance of the winding ofthe relay R610, the magnet l is insufliciently energized to operate when this circuit is completed. The relay R610, however, operates after an interval to prepare, at RAGI2, a circuit for energizing the winding of R620, the lower winding of R630 and the winding of R440 in series. At RA6I3, the relay RBIO opens the path normally short-circuiting the resistor 615, thereby to insert further resistance in the above-traced circuit serially including its own winding and the winding of the magnet 05L At RAG, the relay R610 opens an alternative circuit for energizing the magnet 651 and completes an obvious circuit for energizing the slow-to-release relay R600. The relay R600, upon operating, prepares the alternative circuit for energizing the magnet 65L Assuming that the wipers of the distributor switch 640 are positioned in engagement with the contacts corresponding to the trunk 26 and associated position finder 20, the relay R610 completes, at RASII, a circuit for energizing the operating magnet 451 of the finder switch 450, this circuit extending from ground by way of RAGI I, RA03I, the wiper 646, C416 and the winding of the magnet 451 to battery. The magnet 451, upon operating, completes, at its armature 458, a circuit extendingby way of C411 and the wiper 641 for energizing the upper winding of R630. The relay R630'now operates to open, at RA63I, the operating circuit for the magnet 451, causing this magnet to release and advance the wipers 454 to 456 inclusive, one step. At its armature 458, the magnet 451 opens the circuit for energizing the relay R830. Accordingly, the

potential, as extended -tery., The resulting illumination relay R660 restores to recomplete the circuit for energizing the magnet 451. The interrelated operation of the magnet 451 and the relay R630 continues until the wipers 454 to 456, inclusive, are advanced into engagement with the contacts terminating the conductor individual to the order operator's position 2|. When the wipers of the switch 450 are advanced to this position, the above-mentioned circuit is completed for energizing the three relays R440, R620 and R630 in series, this circuit extending from ground by way of RA6I2, the winding of R620, the lower winding of R630, the wiper 648, C412, the wiper 456, the contact springs 435 and the winding of R440 to battery. When this circuit is completed, ground through the winding of R620 and the lower winding of R630 to the left winding terminal of the relay R440, is impressed upon the contact associated with the wiper 401 which corresponds to the order operator's position 2|. This contact is multipled to the corresponding contacts of each of the other position finders having access to the order operator's position 2| so that all of these contacts are eflectively grounded, thereby to busy the order operator's position 2| to the various position finders. When the above-traced circuit is completed the relay R630 is held operated independently of the magnet 451 so that the operating circuit for this magnet cannot be recompleted and operation of the finder switch 450 is arrested. The relay R620 upon operating completes, at RA62I, a circuit for energizing the lowerwinding 01' R460, this circuit extending from ground by way of RA62 I, the wiper 650, C413 and the lower winding of R460 to battery. Upon operating the relay R460 completes a holding circuit for itself and the relay R440, this circuit extending from groundby way of the upper winding of A460, RA466, the wiper 456, the contact springs 435 and the winding of R440 to battery. The gro d potential, as extended through the upper w ding of R460 to the left terminal of R440 also serves to mark' the operator's position 2| as busy in the bank contacts of the various position finders individual to the order trunks. At its armatures RA46| and RA462, the relay R460 connects the talking conductors of the trunk 26 to the substation apparatus provided at the order operators position 2|. At

RA465, the relay R460 completes a circuit for energizing the call lamp 663 individual'to the trunk line 26, this circuit extending from ground by way'of the jack spr n s 664, C416, RA465, C419 and the filament .of the lamp 663 to batof this lamp serves to inform the branch exchange operator that an incoming call on the trunk 26 should be answered. At RA464 and its associated resting contact the relay R460 opens one of the paths over which ground potential is normally impressed upon the all-trunks-busy conductor C415. At RA464 and its associated working contact the relay R460 completes a path including C414 for impressing ground potential upon the test contact associated with the wiper 649 which corresponds to the finder switch 450, thus identifying the trunk 26 as busy in the bank contacts of the distributor switch and short circuiting the relay R6l0.

The relay R440 operates shortly following the operation 01 the three relays R620, R666 and R466 and, upon operating, opens, at RA442, one of the multiple paths over which ground potential is normally impressed upon the conductor C466. At RA443 the relay R440 completes the 649 is driven into engagement with the tact of the associated contact set. When an all-- erating circuit for the motor magnet 451, and to interrupt the operating and holding circuits for the relays R620 and R630, causing these two relays to restore. At RA6I4, the relay R6I0 opens the operating circuit for the slow-to-release relay R600 and completes a circuit extending through RA60| for energizing the magnet "I of the distributor switch 640 until the relay R600 releases. When energized over this circuitthe magnet 651 attracts its armature 652 to open its test circuit. At RA6I3, the relay R6l0, upon restoring, short circuits the resistor 6l5, thereby further to prepare the test circuit for the distributor switch driving magnet 65L When the relay R600releases, the magnet 65| is deenergized and in cooperation with the associated ratchet and pawl mechanism steps the wipers 646 to 650, inclusive, into engagement with the contacts corresponding to the next switch. In the event the wipers 646 to 650 inclusive, are now standing on a set of contacts corresponding to an idle position finder switch, no further operation of the distributor switch 640 occurs. On the other hand, it the contacts engaged by these wipers terminate conductors extending to a busy position finder switch, ground potential is connected through the associated test contact to the wiper' 649 so that the magnet 65l is again energized and operates to advance the wipers a second step. Due to the circuit interrupting action of the armature 652 the stepping operation of the switch 640 continues until the wiper 649 is advanced into engagement with a test contact from which ground is disconnected; that is, a test contact corresponding to an idle one of the position finder switches. When this occurs the stepping operation of the distributor switch 640 is arrested, the wipers 646 to 650, inclusive, being left standing in engagement with the contacts corresponding to the selected idle position finder switch. If allof the finder switches are busy at the time operation of the distributor switch 640 is initiated, the stepping operation of this switch continues until position finder last conbusy condition or the position finders and associated trunk prevails, all of the relays corre sponding to and including the relay R466 individual to the position finder 29 and trunk' 26 are operated and the conductor C415 is disconnected from ground. Accordingly, when the wiper 649 is operated to engage the contact terminating the conductor'C415 no further circuit is available for energizing the magnet 65! and operation of the distributor switch 640 is arrested. When thereafter one of the position finders is released to cause the restoration of the relay embodied therein which corresponds to the relay R460 01' the position finder 29,ground potential is again impressed upon the conductor C415 to again initiate the stepping operation of the distributor switch the wiper 640, thisstepping operation continuing until the wipers 646 to 650, inclusive, are driven to the position corresponding to the position finder which has been released. Whenthe idle position finder is found, the wiper 649 is disconnected from ground and the magnet 65| is deenergized; Following the hunting operation of the distributor switch 640, as described above, the distributor 30 is fully released and is conditioned to respond to the initiation of a call at another of the order operators positions.

When the branch exchange operator observes the illuminated condition of the lamp 663 indicating that a call is present on the trunk 26 she may answer the call by inserting the answer plug BM in the jack 28. In response to this operation a talking circuit is completed between the cord circuit 660 and the telephone set in use at the order operators position 2|. In addition, the jack springs 664 are disengaged to interrupt the previously traced circuit energizing the call lamp 663. The branch exchange operator, after conversing with the order operator attending the position 2|, may extend the connection to the desired branch exchange substation by inserting the plug 662 in the jack terminating the line extending to this substation and actuating the ringing key embodied in the cord circuit 660 to project ringing current over the line thus selected. For example, if the substation B is desired by the order operator attending the position 2| the branch exchange operator may insert the calling plug 662 in the jack l1 and actuate her ringing key, thereby to cause ringing current to be transmitted over the line l5 and through the windings of the ringer provided at the substation B. After the call is answered at the substation B the branch exchange operator may retire from the connection leaving the desired talking circuit established between this substation and the order operator's position 2|.

In order to release the connection thus established to the substation B the order operator attending the position 2| restores the call key 420 to its normal position. In response to this operation the contact springs 435 are disengaged to open the circuit including the winding of R440 and the upper winding of R460, causing these two relays to restore. When the call key 420 is restored to normal the springs 432 and 433 are also disengaged to open a further point in the path for impressing ground potential upon the distributor start conductor C480. In addition, the contact spring 433 is moved into engagement with the contact spring 434 to reprepare the multiple path, individual to the order operators position 2|, over which ground potential is normally impressed upon the conductor C463. The relay R440 releasing, reprepares, at RA44I, the path for impressing ground potential upon the distributor start conductor C480 and recompletes, at RA442, the above-mentioned path, individual to the order operator's position 2|, for impressing ground potential upon the conductor C403. At RA443 the relay R440 opens the circuit for energizing the busy lamp 424, individual to the order operators position 2| and located at the supervisory operators position 32, thus indicating to the supervisory operator that the order operators position 2| is again idle. The relay R460, upon restoring, opens, at RA463, a further point in the above-traced holding circuit for itself and the relay R440. At RA46| and RA462 the relay R460 opens two points in the completed loop circuit including the upper winding of the induc- 26 to the operators cord circuit 660. The interruption of this loop circuit causes the energization of the disconnect signal lamp provided in the operators cord 'circuit 660, thus indicating to the branch exchange operator that the connection has been-cleared out at the calling operator's position and may be released. At RA464, the relay Rd60 disconnects the marking lead C414 individual to the position-finder 29 from ground,

thereby to mark this finder as idle in the bank contacts of the distributor switch 640. At RA464 and its associated resting contact, the relay R460 completes the multiple path, individual to the position finder 29, for impressing ground potential upon the all-trunks-busy conductor C415.

At RA465, the relay R460 opens a further point in the previously traced circuit for energizing the call lamp 663 individual to the tnmk line 26. The branch exchange operator, upon observing the lighted condition of the disconnect lamp included in the cord circuit 660, may clear out the connection by withdrawing the plugs 66| and 662 from the jacks 20 and II, respectively. Thus, the apparatus utilized in setting up the connection is fully released.

Call storage As indicated previously, the call storage circuit 3| in conjunction with the call storage position finder switches individual to the order trunk circuits, are provided for the purpose of storing calls to the order operators positions when all of these positions are busy and for routing the stored calls to the order operators positions as the operators positions are released in the order in which the calls are stored. More particularly, when all of the order operators positions are occupied with calls or portions thereof are occupied with calls and the others are not attended, the multiple paths individual to the various positions and over which ground potential is normally maintained upon the common conductor C463 are all interrupted. As a result, the relay R540 is energized over a circuit extending from ground through the winding of this relay and by way of C483, the contacts of the no-storage key 422 and the resistor 484 to battery. When energized over this circuit the relay R540 operates to disconnect the wiper 5|5 of the switch 5l0 from ground and to complete an obvious path for applying ground potential to the conductor C3H. This conductor is commonly included in the operating circuits, traced hereinafter, for the relay R320 and the corresponding relays individually provided in the trunk circuits respectively terminating the other order trunks extending to the central oilice |0. The relay R540 is, at this time, the only operated relay in the call storage circult 3|. Further, the call storage distributor switch 500 may at this time occupy any one of its twenty-four operating positions, while the wipers of the call release switch 5l0 may occupy any one of a number of positions behind the po- RA513 to battery. At

R320 to battery. Due to the slow-to-operate characteristic of the relay R3" and the relatively fast operating characteristic of the relay R320, the last-mentioned relay operates to interrupt, at RA32I, the completed operating circuit for the relay R3|0 before the latter relay can operate. Since the relay R3| is prevented from operating, operation of the position finder switch 000 is not initiated in response to seizure of the associated trunk line [0. Further, with the relay R3l0 in its restored position the winding of the relay R300 is not bridged across the conductors of the trunk line [0 to give the central oilice operator answering supervision in the manner previously explained. Also, the operating circuit for the relay R320 is not opened and no circuit is provided for energizing either of the windings of the stop relay R350. The relay R320 upon operating completes, at RA32I', an obvious path for bridging the winding of the relay R300 across the conductors of the trunk I0 in series with the resistor 3l5, whereby the relay R300 is held operated through energization from the central ofllce battery. The resistance value of the resistor 3l5 is such that the answer relay of the cord circuit in use in the central ofllce is not sufliciently energized to is completed. At RA323 and its associated resting contact, the relay R320 opens the path normally short-circuiting its lower winding. At RA322 and RA323, the relay R320 completes a locking circuit for itself, which circuit extends from ground by way of RA330, RA322, the lower winding of R320 and the resistor M6 to battery. At RA324, the relay R320 completes a circuit extending by Way of C380 for energizing the trunk call storage lamp 426 individual to the trunk l0, thereby indicating that a call present on the trunk line l0 has been placed in storage. At RA325, the relay R320 prepares a circuit, traced hereinafter, for energizing the stop relay R330. At RA326, the relay R320 completes a circuit for energizing the relay R520, this circuit extending from ground by way of RA326, C313, the winding of R520 and I RA321 and its associated resting contact, the relay R320 opens a point in the release or homing circuit for the operating magnet 369 of the call storage finder switch 300. At RA321 and its associated working contact; the relay R320 completes a circuit for energizing the magnet 369, this circuit ground by way of the restored armature RA532, C310, RA321, RA331, the armature 310 and the winding of the magnet 360 to battery. Due to ,the circuit interrupting action of the armature 310, the magnet '36! operates buzzer fashion when the circuit just traced is completed and, in

' cooperation with its associated ratchet and pawl mechanism, advances the, wipers 365 to 360, inclusive, until thesewipersfind the position marked in the contacts of thecall storage position distributor switch 500. Assuming, for example, that the wipers of the switch 500 stand in engagement with their respective associated fourth;

contacts, the wipers of the switch 360 are advanced three steps, at which time they also enextending from operate when this path to the supervisory operator contacts. At RA336, the relay R330 completes an obvious locking circuit for itself. At M3", the relay R330 completes an obvious multiple path including the resistor M5 for bridging the winding of the relay R300 across the conductors ofthe trunk line l0. At RA332, the relay R330 opens a point in the above-traced operating circuit for the relay R320 and connects multiple ground to the common conductor 3", thereby to insure the storing of a later initiated order tnmk call initiated substantially simultaneously with the release of an order operator's position. At RA333 and RA330, the relay R330 transfers locking ground for the lower winding of the relay R320 to the operated make springs associated with RAI. At'RA335, the relay R330 prepares a path, traced hereinafter, for short-circuiting the lower winding of the relay R320 when an order operator's position becomes available.

When the relay R560 is energized in series with the lower winding of R330 it operates after an interval to complete, at RA56I, a circuit extending by way of RA53I for energizing the operating magnet 501 of the switch 500. When thus energized, the magnet 501 attracts its associated armature 508 to open the circuit through the winding of R560 and the lower winding, of R530. thereby to cause the release of the relay R560. This relay releasing opens the circuit forenergizing the magnet 501, whereby this magnet in cooperation with its associated ratchet and pawl mechanism steps the wipers 500 to 506, incluslve, of the switch 500 to the next storage position. Since this next storage position is not occupied with a stored call, the wiper 506 engages an open circuited contact and no further operation, of the relay R560 and the magnet 501 0cours. The purposeof stepping the wipers of the switch 500 one step in the manner just explained is to mark the next storage position of this switch as the position to be assigned to the next call routed over one of the order trunks at a time when all of the order operators positions are busy.

As indicated above, the relay R520 is energized and operates in response to operation of the relay gage their respective associated fourth contacts. 7

When the wiper 361 engages its associated fourth contact, a circuit is completed for energizing the lower winding of R330 in series with the relay R560, this circuit extending from ground by way of RA325, the lower winding of R330, the switch wipers 361 and 506 and their respective associated fourth contacts, the armature 500 and R320, immediately the call is initiated on the trunk line l0. The relay R520 operating, completes, at RA52 I; an obvious circuit for energizing the operating magnet. 5" of the switch "0. This magnet attracts its armature 5" to com plete an obvious circuit for energizing the slowto-release relay R510. The relay R510 operating prepares, at HA5", a holding circuit for itself; prepares, at RA5I2, a circuit for energizing the lower winding of R550; and opens, at RA5'I3, the established operating circuit for the relay R520. The relay R520 releasing opens the established circuit for energizing the magnet 5. The magnet releasing advances the wipers of the switch 5|0 one step and retracts its associated armature 5" to interrupt the operating circuit for the relay R510. The relay R510 releasing recompletes the operating circuit for the relay R520 which reoperates to again complete the operating circuit for the magnet 5". The interrelated operation of the-two relays R520 and R510 and the magnet 5l1 continues until the wipers of the switch 5l0 are positioned on the contacts marked by the setting of the call storage finder switch 366. In the case assumed the wipers of the switch 366 are rapidly advanced to engage their respective associated fourth contacts in response to operation of the relay R326. Accordingly. the wipers of the switch are advanced to engage their respective associated fourth contacts. When the wiper 5l6 engages its associated fourth contact, the above-mentioned circuit is completed for enthe lower winding of R556, this circuit extending from ground at RA35'I by way of the wipers 366 and 5l6 and their respective associated fourth contacts, M512 and the lower winding of R550 to battery. This circuit is completed while the relay R516 occupies its operated position and, accordingly, when the relay R556 operates the above-mentioned locking circuit for R516 is established, this circuit extending from ound by way of RA55I, RA5'H and the winding of R516 to battery. Thus, the two relays R556 and R516 are locked up under the control of the relay R356 to prevent any further operation of the relay R526 and the magnet 5". At this point it is noted that in the trunk circuit IS, the relays R366, R326 and R336 are operated, while in the call storage circuit 3i the relays R566, R556 and R516 are operated. With the ap a atus in this condition no further operation thereof occurs until one of the order operators positions is released, the stored call on the order trunk I6 is abandoned, or a second call is routed over one of the order trunks.

If the call present on' the order trunk I6 is abandoned at the calling central ofllce subscrib ers substation prior to the release of one of the order operators positions and the established connection to the line I6 is cleared out at the operators switchboard in thecentral exchange II, the relay R366 restores. Upon restoring, this relay, at its armature RA36I, opens the established locking circuit for the relay R326 and applies multiple ground to the all-trunks-busy conductor C312. At RA362, the relay R366 opens a point in the previously traced operating circuit for the relay R326. At RA363, the relay R366 interrupts the locking circuit for the relay R336. Thus, the two relays R326 and R336 are caused to release. The relay R326 releasing Opens, at RA326, the circuit for energizing the trunk call storage lamp 426; reprepares. at RA32I, the operating circuit for the relay R3l6; opens, at RA325, a further point in the operating circuit for the relay R336; opens, at RA326, the path individual to the trunk circuit [6 over which ground potential is impressed on the conductor C313; and, at RA32I,- opens a point in the initially completed operating circuit for the magnet 36! and prepares an alternative circuit for energizing this magnet. The relay R336 releasing opens, at RA33I, the path bridgin the winding of the relay R366 across the conductors of the trunk l6; disconnects, at RA332, multiple ground from the common conductor C3"; reprepares, at RA332, the operating circuit for the relay R326; opens, at RA333 and RA336, an additional point in the holding circuit for the relay R326; opens, at RA335, the prepared path for shortcircuiting the .lower winding of R326; opens, at RA336, a further point in its own locking circuit; and completes, at RA33I, the above-mentioned alternative circuit for energizing the magnet 363. This circuit extends from ground by way of the wiper 365, the multipled contacts numbered from 2 to 25, inclusive, of the contact set 36l, RA321, RA33I, the armature 316 and the winding of the magnet 36!! to battery. Due to the circuit in terrupting action of the armature 310, the wipers of the switch 360 are rapidly advanced step by step to their respective home positions at which time the wiper 365 engages its associated first contact. Since this contact is not connected to ground, the circuit for energizing the magnet 666 is interrupted and operation of the switch 366 is arrested. Thus, the wipers of the switch 360 are left standing in their respective home positions. During this stepping operation of the switch 366 and when the wiper 366 is disengaged from its associated fourth contact, the previously traced operating circuit for the relay R550 is interrupted causing this relay to restore and open the locking circuit for the relay R516. As a result, the relay R510 restores after an interval to reprepare the operating circuit for the relay R526. Under the circumstances assumed, wherein only the call originating on the order trunk 16 has been stored, ground potential is not present on the common conductor C313 when the relay R616 restores. Accordingly, the'relay R520 is not reoperated to initiate operation of the switch 5". Following the operations just described, the order trunk circuit i9 is fully restored to normal and all of the relays in the call storage circuit, with the exception of the relay R540. are released.

If the order operator's position 2i is released while the call originating on the order trunk I6 is in storage, the relay R446 embodied in the apparatus provided atthis position is released and the position is marked as idle in the bank contacts of the position finders having access thereto. The relay R440 releasing completes, at

RAHZ, its associated path for impressing ground,

potential upon the common conductor C463, thereby to short-circuit the winding of the relay R540. The relay R540 releasing disconnects ground from the common conductor C3" and completes, at RAE, the previously mentioned path for short-circuiting the lower winding of R326, this path extending from ground by way of RA56I, the wipers 5i5 and 366 and their respective associated fourth contacts, RA335, the lower winding of R320, RA323, RA322, RA336, RA333 and RA30I backto ground. When thus deenergized, the relay R326 releases to short-circuit its lower winding and open the short-circuiting path just traced. At RA324, the relay R320 opens the previously traced circuit for energizing the trunk call storage lamp 626, thereby indicating to the supervisory operator attending the position 32 that the call present on the order trunk l6 has been released from storage. At RA325, the relay R320 opens a further point in the previously traced circuit for energizing the lower winding of R330 and the winding of R566 in series. At RA326, the relay R326 opens the associated path for impressing ground potential on the conductor C313. At RA32I, the relay R326 opens a further point in the initially completed operating circuit for the magnet 369 and prepares the above-traced alternative circuit for energizing this magnet. At RA32 i the relay R320 completes the previously traced operating circuit for the relay R3". The relay R3i0 operating bridges the winding of the relay R300 directly across the conductors of the trunk i8, thereby to cause the operation of the answer relay provided in the operator's cord circuit in use in the central oilice I0. The relay R3i0 operating, also initiates operation of the position finder 660 to find the order operator's position 2i which has been released, all in the manner previously described. At M3, the relay R3" opens a point in the previously traced operating circuit for the relay R320. When the wipers of the position finder 400 are positioned on the contacts corresponding to the operator's position 2|, the relays R350 and R040 are energized and operate in the manner hereinbefore described. The 'relay R350, in operating performs the functions previously described, and, in addition, opens, at RA355, the established looking circuit for the relay R330 permitting the latter relay to release. At RA351, this relay R35 opens the previously traced operating circuit for the relay R550, thereby to cause the sequential release of the relays R550 and R510 in the order named. Thus, the apparatus provided in the call storage circuit 3kg; fully restored to normal. It is to be noted that if none of the other order operators positions have been released substantially simultaneously with the release of the order operators position 2|, the relay R440 in operating opens the only completed multiple path for impressing ground potential upon the common conductor C453. As a result, the operating circuit for the relay R540 is reestablished and this relay operates. with the relay R540 operated, further calls routed over the order trunks to the order operators positions are stored until such time as a corresponding number of the order operators positions are released.

The relay R330 releasing opens, at RAMS, RA! and RA332, additional points in the previously traced operating, holding and release circuits for the relay R320; opens, at RA335. a further point in its own locking circuit; opens, at RASSI, the initially completed path for bridging the winding of the relay R300 across the condoctors of the trunk I0; disconnects, at RA332, the conductor 31! from ground; and reprepares, at RA332, the operating circuit for R320. At RA331, the relay R330 completes the previously traced alternative circuit for energizing the magnet 359, causing this magnet, in cooperation with its associated ratchet and pawl mechanism, to advance the wipers 365 to 358, inclusive, step by step until they are moved to their respective home positions. Following the operations just described, the desired connection between the central oflice subscriber's substation and the order operators position 2| is fully established. This connection may be routed to the branch exchange switchboard or through this switchboard to one of the branch exchange substations or may be released under the control of the operator attending the position 2|, all in the manner previously described.

In the event a plurality of calls intended for the order operators positions are routed over the order trunks at a time when all of the order operators positions are busy, these calls are assi ned successive storage positions by the switch 500. In this regard it will be recalled from the previous explanation that the wipers of the switch 500 were advanced one step to a new call storage position in response to storage of the call routed over the order trunk It. More specifically, these wipers were advanced to engage their respective associated fifth contacts. If, with the wipers of the switch 50. standing in this position, a second order trunk call is initiated prior to the release of one of the order operators positions the trunk circuit apparatus associated with the order trunk in use operates in substantially the manner described above with reference to the order trunk circuit l9, except that the wipers of the call storage finder switch embodied in. the

second trunk circuit are operated to engage their respective associated fifth contacts and are left standing in this position. Following such operation of the second call storage finder switch, the wipers of the switch 50l are advanced an additional step and are left standing in engagement with their respective associated sixth contacts. With these wipers in this position a third order trunk call initiated prior to the release of any of the order operators positions is assigned the sixth storage position under the control of the wipers embodied in the switch 500. It wilh thus be apparent that order trunk calls initiated at a time when an all-busy condition of the order operators positions prevails are assigned successive storage positions under the control of the switch 500.

The purpose of the switch 510 and its associ ated control apparatus is to release the calls from storage in the same order as they are stored. Thus, it in the case considered above a plurality of the trunk calls are stored prior to the release of the order operator's position and the call on the order trunk 10 is the first call stored, the order operator's position 2| is assigned to the use of the order trunk it. This is true for the reason that the relays R550 and R510 are held locked up under the control of the relay R350 regardless of the number of steps taken by the wipers of the switch 500 following the locking up of these two relays. Under these circumstances,

when the relay R350 operates in response to op-.

eration of the position finder 00 to seize. the order operator's position 2!, it opens the established operating circuit for the relay R550 causing the latter relay to release and open the established locking circuit for the relay R510. The relay R510 restores after an interval to recomplete, at RA513, the operating circuit for the relay R525. This latter relay operating completes the circuit for energizing the magnet 511 which magnet, in turn, completes the operating circuit for the relay R510. The relay R510 operating opens the operating circuit for the relay R520 to cause the sequential restoration of the latter relay and the magnet 511, whereby the wipers 5 to 5l8, inclusive, are advanced to engage their respective associated fifth contacts corresponding to the second stored call. If this call has not been abandoned, ground potential is present upon the fifth'contact oi the contact set 5|: as a consequence of the setting of the call storage finder switch individual to the order trunk over which the second stored call was routed. Accordingly, the relay R550 reoperates to close the lockingcircuit for the relay R510 and thus prevents further operation of the relay R520 and the magnet5l1. The relays R550 and R510 are thus locked upnnder the control of theground potential is not present upon the contact of'the set 513 which corresponds to the second stored call, namely, the fifth contact of this set. Accordingly, a second cycle of operation of the two relays R510 and R520 and the magnet 5" occurs so that the wipers of the switch 5| 0 are advanced to engage their respective associated sixth contacts. If the stored call corresponding to this position of the switch 510 has also been abandoned the cyclic operation of the two relays R510 and R520 and the magnet again occurs to advance the wipers of the switch 5l0 into engagement with their respective associated seventh contacts. When the position of the switch 5" corresponding to the next call in storage is found, the relays R550 and R510 are locked operated under the control of the relay which corresponds to the relay R350 and is embodied in the trunk circuit associated with the order trunk on which this call is present.

If a stored order trunk call next to be released from storage by the call storage circuit 3| is abandoned before an order operators position becomes available the call release switch 5I0 is automatically advanced to the position corresponding to the next stored call, assuming that additional order trunk calls are in storage. Thus, if a trunk call originating on the trunk is one of a number of order trunk calls in storage, the switch 5" occupies a position corresponding to the call on the trunk I8 and this call is abandoned, the trunk circuit apparatus I5 is caused to be released in the manner previously described. During the release of this apparatus the wipers of the switch 350 are restored to normal under the control of the magnet 350.

This homing operation on the part of this switch 350 results in the removal of ground potential from the contact of the set 364 which corresponds to the position occupied by the wipers of the switch SN and, hence, the relay R550 is deenergized and restores. This relay restoring initiates the cyclic operation of the two relays R510 and R520 and the magnet 5| 1 in the manner previously explained, thus causing the wipers of the switch 510 to be operated step by step until the contacts corresponding to the next stored call are engaged thereby. When the wipers of the switch 5l0 reach the position corresponding to the next call in storage, the relays R550 and R510 are locked up under the control of the relay corresponding to the relay R350 and embodied in the trunk circuit associated with the order trunk on which the next stored call is present.

In order to prevent useless operation of the switch 500 when more than twenty-three of the call storage positions thereof are occupied with stored calls and to prevent later initiated 'calls from obtaining preferred storage positions, an arrangement comprising the slip multiple extending between the contact sets SM and 503 of this switch is provided. More specifically, this slip multiple is such that when the wiper 504 engages any of its associated contacts except the first, it is connected by way of one of the conductors of the multiple to the contact next succeeding the engaged contact and provided in the contact set 503. To this end, the second contact of the set 503, which corresponds to the first storage position of the switch 500, is connected to the twenty-fifth contact of the set 50l and the contacts numbered from 3 to 25, inclusive, of the contact set 503 are respectively connected to the contacts numbered from 2 to 24, inclusive, of the contact set 50!. With this arrangement it call storage is started and all but one of the twentyfour available storage positions are subsequently assigned at a time when no order operators positions are available, the wiper 504 will be connected to a grounded contact in the contact set 503. Thus, if the wipers 504 to 505, inclusive, occupy positions in engagement with their associated third contacts when the next to last storage position is filled, these wipers will not be advanced from this-position. Under these circumstances ii the wipers of the finder switch 300, for example, occupy positions in engagement with their associated fourth contacts, corresponding to the fourth storage position of the switch 500, ground potential is extended from RA325 through the lower winding of R330 and the wiper 301 to the fourth contact of the contact set 503. Accordingly, a circuit is completed for energizing the relay R530, this circuit extending from the grounded fourth contact of the set 503 by way of the third contact of the set 5", the wiper 504, C402, the contacts of the step-0n switch 42l, 040i and the winding of R530 to battery. The relay R530 operating disconnects ground from the conductor C314 commonly included in the various operating circuits for the motor magnets of the storage position finder switches corresponding to and including the switch 350, thereby to prevent any of these switches which are associated with idle order trunks from being operated. At RA53I, the relay R530 opens a point in the above-traced operating circuit for the motor magnet 501, whereby operation of the distributor switch 500 is prevented. With the apparatus in this condition if an order trunk call is initiated, the relays embodied in the trunk circuit associated with this trunk line, which correspond to the relays R300 and R320 of the trunk circuit l3, are caused to operate, the last-mentioned thereof functioning to complete a locking circuit for itself. Following the operation of these two relays the trunk circuit in use remains locked up until the call routed thereover is abandoned or until a call storage position becomes available in the switch 500 through the release of one of the previously stored calls from storage.

The relay R530 remains operated until such time as the stored call corresponding to the storage position of the switch 500 next succeeding. that occupied by the wipers of this switch is released from storage. It will be apparent from the foregoing explanation that this stored call will be the next call to be released from storage under the control of the switch 510. When this call, which, as was stated above, is present on the order trunk I0, is released from storage," the relay R320 is caused to release and the switch 350 is automatically restored to its home position, all in the manner previously explained. The relay R320 releasing disconnects ground from the third contact of the contact set 503 in the switch 500 and in so doing interrupts the previously traced operating circuit for the relay R530. The relay R530 releasing, preparesat RA53I, the operating circuit for the magnet 501. At RA532, the relay R530 again connects the common conductor C314 to ground so that if an unstored call is present on one of the order trunks a circuit is completed for energizing the motor magnet of the call storage finder switch associated with the trunk on which the unstored call is present. This finder switch operates to advance its wipers into engagement with their associated third contacts at which time the previously described trunk circuit relay operations occur to place the unstored call in storage. Incident to these trunk circuit relay operations, ground potential is impressed upon the third contact of the contact set 503 to cause the sequential operation of the relay R550 and the magnet 501 allowed by the release of these two circuit controlling devices.

so that the wipers of the switch 500 are advanced into engagement with their respective associated fourth contacts. At this time ground is again applied over one of the slip multiple conductors to the wiper 504 so that the relay R530 is reoperated to perform the functions previously described. From the foregoing explanation it will be apparent that while twenty-four storage positions are actually provided in the switch 500 only twenty-three of these positions can normally be used simultaneously. It will further be apparent that the slip multiple arrangement between the contact sets M and 503 of the switch Illfunctions to prevent useless operation of this switch when all of the storage positions are filled and to prevent later initiated order trunk calls from obtaining preferred storage positions in the switch 500, thus insuring the release of the calls from storage in the same order as they are stored.

In order further to prevent unnecessary delay in releasing calls from storage an arrangement is provided for preventing the wipers of the switch 5l0 from being operated to a position in advance of the position occupied by the wipers of the switch 500. In this regard it will be recalled from the foregoing explanation that when all of the order operators positions are busy the,s relay R50 is operated. With this relay operated, if a call originates on the order trunk iii,

the relay R320 of the trunk circuit I9 operates to complete the previously traced operating circuit for the relay R520, thereby to initiate the stepping operation of the switch 5l0. Simul taneously with the initiation of operation of the switch 5l0, operation of the switch 350 is initiated in the manner previously explained. It the operation of these two switches is initiated at a time when the wipers of the switch 500 are engaging their respective associated twenty-fourth contacts, twenty-four steps on the part of the switch 350 are required to position the wiper 358 on the associated twenty-fourth contact to com plete the circuit for energizing the stop relay R550 associated with the switch 5l0. on the other hand, if the wipers of the switch are engaging their associated twenty-third contacts when operation of the switch 5|0 is initiated, only three steps are required on the part of the switch H0 in order to advance the wipers of this switch to a position beyond that occupied by the contact of the set 5 is connected to the second contact of the contact set 502 and the contacts numbered from 2 to 24, inclusive, of the contact set 5 are respectively connected to the contacts numbered from 3 to 25, inclusive, of the contact set 502. With this arrangement an alternative circuit is provided for energizing the relay R550 each time the wipers of the switch 5| 0 are advanced to a position one step behind the position occupied by the wipers of the switch 500 at a time when. an order trunk call is to be placed in storage. Thus, in the foregoing illustration wherein a call originating on the order trunk I8 is assigned to the twenty-fifth storage position of the switch 500, ground potential is impressed upon the conductor C313 through operation of the relay R320 in the manner previously explained and the stepping operation of the two switches 350 and H0 is substantially simultaneously initiated. When, however, the wipers of the switch 5l0 have been advanced to engage their associated twenty-fourth contacts the above-mentioned alternative circuit is completed for energizing the relay R550 regardless of the position occupied by the wipers of the switch 350. This alternative circuit extends from ground by way of RA320, C313, the wiper 505 and its associated twenty-fifth contact, the wiper 5| 4 and its associated twenty-fourth contact, and the upper winding of R550 to battery. When this circuit is completed the relay R550 operates to complete the previously traced locking circuit for the relay R510, thereby to arrest the stepping operation of the switch H0 in the manner previously explained. When thereafter the wipers oi the switch 500 are advanced to the next sucwipers of the switch 500. In such case a complete cycle of operation of the switch 5|0 is obviously required before the wiper 5l6 engages the contact in the contact set 5l3 which has been marked through operation of the switch 350 to cause the operation ,of the stop relay R550- Although the step-by-step operation of the switch 5| 0 is relatively slow as compared with that of the storage position finder switchesindividual to the order trunk circuits, it is easily possible for the wipers of the switch 5l0 to be advanced three or more positions while the wipers of the switch 350 are being advanced through twentyfour or less positions. Hence, it would be possible for a substantial time interval to elapse between the release of an order operators position and the release 'of a call from storage.

In order to obviate the difl'iculties outlined in the preceding paragraph, there is provided an arrangement which comprises a slip multiple extending between the contacts of the contact set502 embodied in the switch 500 and the contacts of the contact set 5 embodied in the switch 5". More specifically the twenty-fifth ceeding storage position, in the manner previously described, the alternative circuit for energizing the relay R550 is interrupted at the wiper 505 and its associated twenty-fifth contact. By this time, of course, the wipers of the switch 350 have been positioned in engagement with their respective associated twenty-fifth contacts representing the storage position assigned to the "trunk circuit 10 by the switch 500. Also, ground potential is still present upon the conductor-C313 so that when the relay R550 releases the relays R510 and R520, in cooperation with the operating magnet 5", function to cause the wipers of the switch M0 to be advanced into engagement with their respective associated twenty-fifth contacts. At this time a circuit extending from ground at RA351 and through the wipers 368 and 5|5 is completed for again energizing the relay R550. -This,relay in reoperating completes the locking circuit, for the relay R510, thereby to prevent further operation of the switch 5l0. From the foregoing explanation it will be apparent that the'provision of the slip multiple between the contact sets 502 and 5H positively precludes the possibility of the wipers of .the switch 5|0 from 7 being advanced to a. position ahead of the position occupied by the wipers of the switch 500.

Supervision As indicated previously, apparatus is provided at the supervisory operators position 32 whereby this operator may maintain a close check on the condition of the order operators positions and the volume of-traiiic routed over the order trunk lines. Thus, provisions are made whereby the operator may monitor any connection involving anyone of the order operators positions. To this end, the jack 9| is provided, the springs of which are connected by way of the conductors

Images