US2277441A - Telephone system - Google Patents

Description

March 24, 1.942.

c. D. KQECHLING TELEPHONE SYSTEM 3 Sheets-Sheerl 1 Filed July, 1940 /N V E /V TOR c. 0, Kob-CHL /NG B V T TORNE V March 24, v1942., c. D. KOECHLING 2,277,441

TELEPHONE SYSTEM Filed July 5, 1940 3 sheetsheet 2 Q I N n v I n, /N VEN TOR c. .0. KOECHL/NG March 24, 1942.

y Filed July 5, 1940 C. D. 'KOECHLING TELEPHONE SYSTEM ATTE/WANTS ser F/as I A7' LOCATION C 3 Sheets-Sheet 3 v A l, IL. Il

5s/I, To laz ncl/.frits ok NI/ENTOR C. D. KOECHL/NG BV ArrjORA/Ey Patented Mar. 24, 1942 OFFICE TELEPHONE SYS TEM Application July 5, 1940, Serial No. 344,039

7 Claims.

This invention relates to telephone systems and particularly to automatic working, being especially directed to transferring means whereby connections extended to one point may be rerouted to another point.

The object of the invention is to provide facilities whereby flexible operation by a subscriber having a plurality of terminating stations in different localities may be had.

The prior art affords a number of disclosures of telephone systems wherein calls may be transferred from one called subscriber to another called subscriber. Generally speaking such facilities are provided in special private branch exchange arrangements. The present invention, however, contemplates a plurality of private branch exchange installations and the object is to transfer a vcall incoming to one such private branch exchange operator to another and particularly where the different private branch exchange switchboards are in diierent localities. The present invention therefore differs from previously known arrangements in several essential aspects.

In accordance with one feature of the invention the transfer arrangements While still controlled by a called subscriber are nevertheless located at the distant end of the line. Specifically, the transfer is made at the central office end of a trunk rather than locally in the private branch exchange circuits.

In accordance with another feature the transfer is more in the nature of a rerouting since the new connection is not directively extended to a particular called subscribers line but rather to another group of lines leading in the desired direction.

A further feature of the invention is a simple key controlled means for initiating the transfer or rerouting operation at the distant end of the trunk line. In the specific embodiment of the invention herein employed a differential relay at the central office end of a trunk is made to respond to a manual key controlled operation at the private branch exchange end of the trunk.

In accordance with another feature each of a group of central cnice lines terminating in a distributing means for allotting incoming calls to individualattendants of a group has in it a transfer means operated by a common key at each attendants position to affect transfer means at the central office end of the line for there transferring or rerouting the call over one of another group of lines extending to a different location. Where a subscriber has premises at two widely separated locations and where cable conductors are at a premium the, present invention becomes a means ytoward economy especially since additional tie line facilities need not be provided for transferring calls directed to one location which are to be handled at another location.

In accordance with a further feature of the invention such transferred connections may be used for conference purposes since the original connection to the subscribers premises to the irst location is not destroyed after being transferred or rerouted though it may be abandoned.

Other features will be set forth in detail in the following description.

The drawings consist of three sheets.

Fig. l is a schematic diagram showing the general plan of operation; and

Figs. 2 and 3 with Fig. 3 placed to the right of Fig. 2 provide a circuit diagram for explaining the present invention.

In Fig. l the diagram is divided into three portions by a dot-and-dash line. The portion to the left of the vertical ldot-and-dash line represents central office circuits. The two portions to the right of the dot-and-dash line represent the premises of a subscriber, the upper portion representing premises at one location and the lower portion representing premises at another location. A subscriber A wishing to call subscriber B and selecting the telephone number of subscriber B leading to his premises at location C will set up a connection to a line l leading to subscriber B at location C. This line l passes through a transfer circuit 2 over line 3 to an incoming circuit arrangement il which may be attended by an attendant having a circuit 5. The attendant nding that the subscriber A in reality wished to talk to an employee of subscriber B at location D thereupon performs a manual operation within the attendant's telephone circuit 5 which ycauses a relay operation in the incoming trunk circuit 4 and which in turn causes an operation in the transfer circuit 2; thereupon a finder switch 6 will operate and extend the line over an idle trunk circuit 'I leading to the premises of subscriber B at location D where the call will be answered by an attendant having supervision over the central oice trunk circuit 8. In a similar manner a subscriber E may set up a connection to the line 9 leading to the premises of subscriber B at location D. This line passes through a transfer circuit l similar to the transfer circuit 2, thence over a central oice line Il to a trunk termination circuit I2 on the premises of subscriber B at location D, and thence to a termination I3 in a private branch exchange switchboard. The attendant here, finding that the subscriber E actually wished to talk to an employee of subscriber B at location C, performs the same sort of manual operation as the attendant at location C whereupon a dierential relay in the transfer circuit I causes the trunk finder circuit I4 to operate and extend the connection over an idle trunk I5 leading to the premises of subscriber B at location C. The line I6 terminates at that point in an incoming trunk circuit Il which may be attended by the attendant having charge of the attendants telephone circuit 5.

The facilities provided by the trunk nder circuits such as I4 may be utilized by employees of subscriber B for setting up connections to fellow employees at the other location; thus a subscriber F may set up a connection through the station line circuit I8 to a trunk circuit I9 which will cause the operation of the trunk circuit I4 in the same manner as the transfer circuit I0 causes this operation, whereupon the subscriber F, employee of subscriber B, may be connected to a fellow employee at the location C.

The essential parts of the circuit are shown in Figs. 2 and 3. For a more complete disclosure of the circuits of this nature, reference may be had to Patent 1,841,093 to Dahl, January 12|, z

1932. The circuits shown in Figs. 2 and 3 are modifications of the circuit shown in great detail in the above-noted Dahl patent. A subscriber at station may establish a connection, by way of example, through automatic switches 2I and 22 to a line 23 leading to a line termination circuit shown to the right of the dot-anddash line in Fig. 3. This line termination circuit in turn leads to an automatic switch here designated by wipers 24, and 26 leading to an attendants telephone set. The manner in which such a call distributing switch is operated is well known so that here only the parts of the circuit external to the present invention are indicated. It will be noted that between switches 2I and 22 a source of talking battery is furnished to the line in the form of a ground connection to the tip conductor 2l and a battery connection to the ring conductor 28. Battery and ground then cause a current flow in a loop circuit so that this flow of current is equal and opposite in the two conductors. Since these two conductors lead through windings of relay 29, this current flow will not cause relay 29 to operate.

Thus relay 29 is not operated during the normal use of the line from subscriber 2U to the attendant having charge of the attendants telephone set 30.

If the attendant nds that the call should have gone to some other employee at another location, she Will operate transfer key 3I. This key will set up a potentiometer connection including the resistances 32 and 33 and a middle point leading through wiper 26 and thence through the winding of transfer relay 34 to ground on the back contact and lower armature of relay 35. If relay 35 is non-operated, as it would be during the normal use of the line since at that time relay 36 would be operated, then relay 34 will respond. Since the supervisory relay 31 will be operated while the attendants telephone set 30 is oonnected to the line, the operation of relay 34 will place a ground on the ring conductor of the line and through the resistance 38 also on the tip conductor. This will result in a great decrease of current through the left-hand winding of relay 29 and a great increase in the current through the right-hand winding of relay 29. Relay 29 thereupon operates and causes the consequent operation of start relay 39.

Relay 39 through its outer right-hand armature and front contact places a ground on terminal 40 individual to the line 23. Through its inner right-hand armature and front contact relay 39 short-circuits the left-hand winding of relay 29 so that relay :29 will remain operated thereafter even though the attendant at the distant end releases the transfer key 3i. Through its inner left-hand armature and front contact start relay 39 establishes a circuit from ground to the right-hand armature of back contact of cut-o relay 4| through the inner left-hand armature and front contact of relay 39, winding of relay 42 to battery. Relay 42 places a ground on group contact 43 of the finder switch here designated by its group contact wiper 44 and the four upper wipers of which No. 45 is one. Relay 42 also extends a ground from its left-hand armature and front contact to the winding of relay 46 which, becoming operated, closes a circuit from ground, inner left-hand armature and front contact of relay 46, armature and back contact of vertical magnet 4'I, back contact and upper armature of rotary magnet 43, left-hand winding of relay 49, back contact and outermost left-hand armature of relay 59 to battery. Relay 49, becoming operated, establishes a circuit from ground, the inner left-hand armature and front contact of relay 45, the armature and front contact of relay 49, the inner left-hand armature and back contact of relay 5l, Winding of vertical magnet 4l, to battery at the back contact and outer left-hand armature of relay 5U. Vertical magnet 4T moves the brushes of this switch on step in a vertical direction and by opening the circuit of relay 49 thereby breaks its own circuit. Thus the vertical magnet will automatically step until it is stopped by brush 44 reaching terminal 43. At this time a circuit will be established from ground, righthand armature and front contact of relay 42, group terminals 43, brush 44, left-hand winding of relay 5I, back contact and upper armature of rotary magnet 48 through the left-hand winding of relay 49 to battery on the back contact and outer left-hand armature of relay 50. As this circuit is completed while the vertical magnet 4'I has opened the circuit through its armature and back contact, relay 49 will not release at this time and thus vertical magnet 4l will not be allowed to close this circuit. Relay 5I responds and closes through a substitute circuit for holding the vertical magnet 4'I as well as the relay 5| energized through its right-hand winding, front contact and right-hand armature.

A circuit for the rotary magnet 48 may now be traced from battery to winding of rotary magnet 48, front contact and inner left-hand armature of relay 5I, front Contact and armature of relay 49, front contact and inner left-hand armature of relay 46 to battery. Magnet 48 operates to move the brushes represented by 45 in a rotary direction and by moving its armatures breaks the circuit of relay 49. Relay 49 becomes deenergized and thus opens the circuit for the rotary magnet 43. By this means the rotary magnet 48 automatically steps the brushes 45 around until the grounded terminal 40 is reached. At this time ground will be extended to the winding of relay 52. Relay 52 operates. At the same time a connection is set up from battery, the

winding of cut-01T relay 4I through the outer left-hand armature and front contact of relay 39, the terminal 53 and its associated brush, leithand winding of relay 54, back contact and middle left-hand armature of relay 50, right-hand Winding of relay 49 to ground on the front contact and outer left-hand armature of relay 46. The cut-off relay 4l will operate in this circuit and lock through its left-hand armature and front contact to the condition found on terminal 53. Relay 49 will remain operated to prevent further stepping of rotary magnet 48 so that the brushes now having found the proper line will remain stationary. Relay 4l removes ground from the winding of relay 42 and this relay allows relay 46 to become deenergized. Relay 54 is also operated and serves to cut through the line to the contacts of relay 55. Relay 54 locks in a circuit from battery through its right-hand winding, front contact and inner right-hand armature, through the lower armature and front contact of rotary stepping magnet 48 to ground on the front contact of relay 46, which is slow to release and which holds ground until relay 50 becomes operated. Upon the operation of relay 54, ground is extended from the lower contacts of the vertical off-normal set of contacts 56 through the front contact and outer righthand armature of relay 543, left-hand winding of relay 50 to battery. Relay 50 now becomes operated and removes the battery connection for the operation of the vertical and rotary magnets, but establishes a connection for the holding of relay 54 which may be traced from battery to right-hand winding of relay 54, front contact and inner right-hand armature thereof, inner lefthand armature and front contact of relay 55 to ground at the front contact of outer right-hand armature of relay 52. Relay 5I becomes deenergized.

When relay 52 is operated, ringing current from a source connected to conductor 5l is connected through the outer left-hand armature and front contact of relay 52 through the left-hand winding of tripping relay 55, back contact and inner left-hand armature of relay 55, front contact and left-hand armature of relay 52 to line conductor 58, and ground is connected from conductor 59 through the inner right-hand armature and front contact of relay 52, the contacts 60 and 6I controlled by the right-hand armature o-f relay 55 through the front contact and inner right-hand armature of relay 52 to line conductor 62. When the subscriber at the end of the line comprising conductors 58 and 62 responds, the current ilowing through the left-hand winding of relay 55 may be increased and this relay will become operated, its right-hand winding thereupon being included in a circuit to ground at the outer right-hand armature of relay 52. The operation of relay 55 also cuts through the line from the line 23 to the line comprising conductors 58 and 62 and cuts oi all connections through the source of ringing current on conductors 51 and 59.

When the connection is to be released through well-known means, the battery and ground connection to conductors 2'! and 28 will be released, resulting in the deenergization of relay 25. This allows relay 39 to become deenergized which removing ground from the terminal 4) will allow relay 52 to release. This relay removes the ground connection from the conductor connected to its front contact associated with its outer right-hand armature and this breaks the holding circuit for relay 54. This relay in deenergizf ing establishes a circuit for the release magnet 5.3 from battery, the winding of release magnet 63, the upper pair of contacts of the vertical offnorrnal contacts 5.5, outer left-hand armature and back contact of relay 5|, outer right-hand armature and back contact of relay 54, righthand armature and back contact of relay 45 through the lower set of vertical off-normal contacts 56 to ground. Release magnet 63 causes the switch 45 to return to normal.

It should be noted that the connection from subscribers station 20 thus set -up to the attend.- ant having charge of the attendants telephone .Set 30 and thus transferred to the line conductors 58 and 52 leading to the same subscribers premises at a different location, may be made the subject of a conference connection, since the original connection to the attendants telephone set 35 is not destroyed when the connection to the line wires 58 and .62 is established. By the same token, the connection in the new direction may be used and the attendant at the right of Fig. 3 may abandon the connection without disturbing it.

What is claimed is:

1. In a telephone system, a central oiilce, a plurality of groups of lines extending from said central office to subscribers premises, each said group extending to a subscribers premises at a diiferent location, means individual to each of said lines at said central oice responsive to manual control at the said subscribers premises for automatically extending said line from said central office to an idle one of said lines in a predetermined one of said groups of lines.

2. In a telephone system, a central oice, a group of lines extending from said central office to a first subscribers premises, another group of lines extending from said central oice to a second subscribers premises, means at said central cnice individual to each of said lines of said first group responsive to control from said first subscribers premises for causing said lines to be automatically extended to an idle one of said lines of said second group.

3. In a telephone system, a central office, a group of lines extending from said central office to a rst subscribers premises, automatic line nders at said central office for extending each of said lines, a second group of lines extending from said central office to a second subscribers premises, said second group of lines each terminating in one of said line finders and means at said central office individual to each of said lines of said rst group under manual control from said first subscribers premises for automatically causing the operation of said line iinders.

4. In a telephone system, a central oice, a group of lines extending from said central oice to a subscribers premises at a first location, another group of lines extending from said central oice to said subscribers premises at a second location, means individual to each of said lines of said first group at said central oflice responsive to means individual to each of said lines of said first group at said subscribers premises at said first location for extending each of said lines of said rst group to an idle one of said lines of said second group extending to said subscribers oice to said subscribers premises at a second location, a differential relay in each of said lines of said rst group at said `central oiiice unresponsive to normal use of said lines, means individual to each of said lines of said rst group at said subscribers premises for operating said differential relays, a switch for extending each of said lines of said first group to one of said lines of said second group, said switches being under control of said differential relays.

6. In a telephone system, a central oice, a group of lines extending from said central oice to a subscribers premises at a first location, another group of lines extending from said central oflice to said subscribers premises at a second location, an attendants position at said first location accessible to said lines of said rst group, means in each of said lines of said rst group at said rst location for placing a distinctive condition on said lines, means in said attendants position common to said lines for operating said distinctive conditioning means, means in each of said lines of said rst group at said central oflice responsive to a said last-named means for extending said lines to one of said lines of said second group.

7. In a telephone system, a central ofice, a group of lines extending from said central oiice to a subscribers premises at a first location, another group of lines extending from said central oiiice to said subscribers premises at a second location, a plurality of attendants positions at said rst location accessible to said lines of said rst group, a transfer relay in each of said lines of said rst group at said first location, a transfer key in each of said attendants positions for controlling said transfer relays, a second transfer relay in each of said lines of said irst group responsive to said rst transfer relays and means under control of said second transfer relays for transferring a call on one of said lines of said rst group to one of said lines of said second group.

CHARLES D. KOECHLING.

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