US2298204A - Telephone system - Google Patents

Description

Oct. 6, 1942. E. L. ERWIN TELEPHONE SYSTEM Filed March 16, 1940 /NVE/VTOR E L ERW/N 27mm/Di Patented Oct. 6, 1942 TELEPHONE SYSTEM Edson L. Erwin, Towaco, N. J., assgnor to Bell Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Application March 16, 1940, Serial No. 324,306

15 Claims.

This invention relates to telephone systems and particularly to telephone systems in which connections are established automatically.

An object of the invention is to improve and simplify such systems and to economically utilize the required equipment.

Heretofore systems of this type have been arranged with common recorders, marking circuits and linking circuits for establishing connections between subscribers lines and between trunks and subscribers lines in which idle links and registers'are seized and controlled by a common marker circuit to effect connections after which the recorder and marker circuits are reverted to common use.

A system to which the present invention is ap. plicable has been disclosed and fully described in a copending application of E. L. Erwin and F. R. Lamberty, Serial No. 325,510, led March 23, 1940. This system contemplates the use of call originating switches of the cross-bar type for establishing connections from calling lines to linking circuits and of call terminating switches of the same type for'establishing Vconnections from said linking circuits to called lines, that'is, all the lines appear as calling lines on call originating switches and as called lines on call terminating switches. Thus when a call is made a select magnet in a call originating switch is operated followed by the operation of a holding magnet to establish a connection from the calling line to a link circuit and when the call is extended to the desired called line a select magnet in a call terminating switch is operated followed by the operation of a holding magnet to establish a connection from said linking circuit to the called line.

In the foregoing system it is a feature of the applicants invention to arrange the marker circuit for establishing connections between subscribers lines so that when a holding magnet in a call originating switch is operated, a holding magnet in the associated callfterminating switch where the calling line also appears as a called line is operated and when a call terminating switch is to be operated for establishing a connection to a called line, the holding magnet in the associated call originating switch is first operated followed by the operation of the holding magnet in the call terminating switch, thus both holding magnets are always operated in a call originating switch and the associated call terminating switch regardless of which of the two switches are used to establish a connection. The purpose of this arrangement is to simplify and improve the operation of the control circuits for the switches.

It is another feature of the present invention to utilize these holding magnetsfor a calling subscriber lock-out arrangement whereby if the calling subscriber fails to dial within a certain time interval after dial tone is received or fails to complete the dialing during this period, the call originating switch is released and the calling subscriber is locked out or prevented from originating another call unless he rst replaces the receiver. The arrangement is such that when this time interval has elapsed, a permanent signal is received causing the release of the holding magnet in the call originating switch which causes the operation of the calling subscribers line relay which in turn locks the holding magnet of the associated call terminating switch and this latter holding magnet being maintained operated now controls circuits that prevent the line relay of the calling subscriber from originating a second call.

' Itis another feature of the invention to utilize these holding magnets for the establishing of revertive calls on party lines. The arrangement is such that when a subscribers station is called which is connected to the same party line as the calling subscribers station, the called subscriber is rung by the designated code ring and when the subscriber answers, the holding magnet of the call originating switch is released to release the established connection and this magnet in turn causes the line relay of this line to operate and hold vthe holding magnet of the call terminating Vswitch operated to maintain the line busy as in the case of the lock-out arrangement described.

This invention has been illustrated in the accompanying drawing in which Fig. 1 shows in diagrammatic form the general switching plan employed in the above-mentioned copending application and to which the present invention may be applied, while Fig. 2 shows the circuits disclosing applicants invention applied to the system ofthe above-mentioned copending application.

Referring now to the drawing and particularly to Fig. l a short description will be made in connection therewith to clearly establish how the applicants invention may be applied in the system disclosed in the above-mentioned application. For a full description of -this system reference may be had to the specication and drawings in the above-mentioned application.

This switching plan as far as the invention is vconcerned discloses call originating crossebar line switches 5 with a group of subscribers lines terminating therein as calling lines and indicated by Vertical lines. There is also shown call terminating cross-bar line switches 6 in which the same group of subscribers lines terminate as called line and indicated by Vertical lines. The switches and 6 are interconnected by a linking system comprising links 1 appearing as horizontal lines in switches 5 and leading into secondary cross-bar switches 8 where they appear as vertical lines and links or junctors 9 appearing as horizontal lines in switches 8 and E. The links 1 also appear as horizontal lines in the recorder switch IU where they may be connected to recorders, one of which is indicated at I I and appears in the recorder switch as a vertical line. A common marker circuit indicated at I2 may be employed as control, means for establishing of connections between lines. In general such a connection may be established in the following manner: When, for example, the

connects it to the link in the group 1 to which the calling subscribers line is connected and also connects this junctor to the called line, for example, line I4, through the switches 6. A further description in regard to the ringing and completing of the connection between the subscribers appears to be unnecessary as far as the present invention is concerned except to point out that when the calling subscribers line I3 is connected to a link in the group 1 and associated select magnet, such as I5, for example for the rst link, would operate followed by the operation of the holding magnet for line I3, such as magnet I6, to establish the connection through switches 5. In the switches 6 where this line I3 also appears the holding magnet such as I1 for this line will also be operated. This is possible as it will be observed that the select magnet for connecting this line through switches 6 is not operative at this time. Consequently,

no harm is done by having the two holding magrying out the applicants invention. Referring now to Fig. 2 a description will be made of the operation of the system with respect to the locking-out of the calling subscribers line in case he fails to dial within a certain period of time after the dial tone has been received or fails to complete the dialing during this period.

This Fig. 2 shows a subscribers line 20 terminating in a call originating switch CO through which a connection from line 2D as the calling line may be established over contacts at the cross-point 2I by the operation of the select magnet 22 and the holding magnet 23 to a link 24 for the extension of a connection as described in connection with Fig. 1 and according to the system disclosed in the above-mentioned application. If the line is a called line the connection may be established thereto over contacts at the cross-point 25 in the call terminating switch TI by the operation of select magnet 26 land the holding magnet 21 from a junctor 28 in accordance with the system as disclosed in the above-mentioned application.

It should be understood that the operations of the circuits shown in this figure should be considered in connection with the above description relating to Fig. 1 and with the disclosure in the above-mentioned application. Only a suiiicient description will therefore be included in this application to clearly illustrate the present in- Vention and reference may be made for further circuit operations if desired to the above-mentioned application. To show how both of the holding magnets 23 and 21 will operate on a call from line 20 as the calling line it may be assumed that the subscriber of line 26 in initiating a call removes his receiver from the switchhook. This closes a circuit for the operation of the line relay 30 from battery and ground through the two windings of this relay and contacts of the holding magnet 23 over the tip-and ring conductors through the loop at the subscribers station. Relay 30 in operating closes a circuit to battery from lead 3I over contacts of the holding magnet 21. This operates a relay in the control and marker circuit to cause operations to identify the calling line, seize the marker circuit, select a recorder and choose an idle link such as 24 for connecting the line 2B to an idle recorder through the call originating switch CO and the recorder switch. The result of these operations is that the select magnet 22 operates over a circuit from ground supplied at the contacts of a relay in the marker circuit to lead 32 through the winding of magnet 22 to battery, followed by the operation of the holding magnet 23 over a circuit from battery through the winding of magnet 23 to ground supplied over lead 33 from contacts of a relay now operated in the marker circuit. This connects the calling line at the cross-point 2| in the call originating switch CO to the link 24. The holding magnet 23 in operating opens the circuit for the line relay 30 which now releases to open the circuit for the lead 3|. A pulsing relay 34 in the recorder is now operated over a circuit closed through the subscribers loop over the tip-and-ring conductors, contacts at the cross-connecting point 2l, link 24, through the connection at the recorder switch and the windings of relay 34 to battery and ground. This connection also extends to a dial tone source 35 which transmits a dial tone to the calling subscriber so that the subscriber may begin dialing of the desired number. When the number of the called subscribers line has been dialed, including the ringing and coin control circuit code digit, and recorded and the circuits have operated as described in connection with Fig. 1 to select an idle junctor such as 36 in the group 9 and connected to the link 24 through the secondary switch 8, a circuit is closed for the operation of the select magnet 31 in the terminating switch T-I from battery, winding of this magnet, lead 38 to ground at the contacts of a relay in the marker circuit. The operation of this select magnet indicates the selection of the idle junctor 36 and this junctor circuit is then connected to the called line 39, rst by the operation of the holding magnet 40 in the call originating switch CO over lead 4I from battery, winding of this magnet, lead 4I and contacts of a relay in the marker circuit to ground. Magnet 4I) closes an obvious circuit for the holding magnet 42 in the terminating switch T-I so that the called subscribers line 39 now is connected through the terminating switch T| at contacts 43 and junctor 36 to the link 24 and through contacts 2| to the calling subscribers liner 20. The marker circuit is then released and the ringing of the called subscriber now takes place from a ringing and coin control circuit, over a ringing circuit connector switch. When the called subscriber answers the ringing circuit is released and the holding magnets 23 and 42 are held over the sleeve lead while the magnets 22 and 31 are released on the release oi the marker circuit. Conversation between the calling subscriber on line 24, and the called subscriber on line 39 over the link circuit`24Y and the junctor circuit 35 through the secondary switch 8 may new take place.

Returning now to the point where the calling line was connected to the link 24 by the operation of the holding magnet 23, it should be noted that the circuit from ground on lead 33 for operating the holding magnet 23 is extended over the sleeve circuit, the contacts at the crosspoint 2|, contacts of the recorder switch, contacts of an intermediate relay which is operated at this time through the windings of relay 44 to battery causing the operation of this relay which causes the release of the select magnet 22 and otherwise prepares the circuits for dialing. The holding magnet 23 and relay 44 are now locked independent of the original operating circuit for this magnet over circuits to ground at contacts of relay 45. The locking circuitfor relay 44 extends from battery of relay 44, contacts of the intermediate relay and of relay 44 to ground at contacts of relay 45 and the locking circuit for magnet 23 extends from battery, contacts at the cross-point 2|, contacts of relay 44 to ground at contacts of relay 45.

Therefore if the subscriber on line has failed to dial or failed to complete the dialing within a certain interval after the operation of relay 44 these locking circuits for the relay 44 and the holding magnet 23 will be opened to release this relay and magnet to disable the cir.-

cuit from establishing a connection to a called subscriber by releasing therecorder and marker circuits and to prevent the calling subscriber from initiating a second connection as long as his receiver remains oi the switchhook.

This is accomplished as follows: It should rst be observed that on the operation of the holding magnet 23 the associated holding magnet 21 in the call terminating switch TI is operated over an obvious circuit. Now if this subscriber fails to complete the call within this .certain interval a timing circuit arrangement is operated bythe operation of relay 44. Relay 44, closes a circuit for relay 45 from battery, left-hand winding of this relay, contacts of relays 44, 46, and 41 to ground. Relay 45 transfers the holding ground for relay 44 and holding magnet 23 to ground at contacts of relay 41. Relay 45 is also locked over a circuit from battery through .its right-hand winding and contact on this relay, contacts of an intermediate relay and contacts of relay 44 to ground. Relay 45 now closes an abvious vcircuit for the operation of rel-ay 46 which locksto ground over contacts of relay 41. Relay 45, in turn, closes an obvious circuit for the operation of relay 48, this relay in turn closing an obvious circuit for the operation of relay 41. Relays 46, 41 and 48 are slow in operating to measure the desired time interval. When relay 45 operated the operating circuit for relay 45 was opened and when relay 41 operated the locking circuits for relay 46, magnet 23 and relay 44 were opened causing the release of magnet 23 and relay 44. Relay 44 in releasing opens a circuit for relay 45 which in releasing opens the operating circuit for relay 46 which no-w releases causing the release of relays 48 and 41 in succession. It should be understood that the above-mentioned time interval within which the calling subscriber must complete a connection may be varied. To this end relays 4S, 41 and 48 which determine this interval may be of any wellknown delayed action type which may be adjusted to suit different requirements in this respect. l

The holding magnet 23 in releasing closes the circuit for the reoperation of the line relay 33 and also opens the operating circuit for the holding magnet 21 but as the line relay operatesA and the holding magnet 21 is slow in releasing relay v33 closes a locking circuit for this holding magnet from battery, winding of magnet 21,' contacts of this magnet to ground at contacts of relay 3D. Relay 33 now. in operating also closes a circuit from ground through its contact to the lead 53 which is the busy test lead to indicate that the calling line is busy. Hence by maintaining of the holding magnet 21 operated the circuit from battery through contacts of relay 34 to lead 3| is opened at contacts of magnet 21 and thus the initiation of operations to establish a connection a second time is prevented. This condition of the circuit now prevails until the calling' subscriber replaces his receiver on the switchhook when the line relay 3@ releases causing the release of the holding magnet 21. Thus it will be seen that the holding magnet 21 for the call terminating switch T| is employed to prevent a second call from being initiated as long as the calling subscribers receiver remains oir the switchhook.

In regard to revertive calls from one subscriber to another on a party line, this arrangement operates as follows. When the connection has been established to test the called line it is found busy, due to the connection over lead 59 being opened. The open condition of lead 5| through contacts of the holding magnet 21 prevents certain relays in the marker circuit from operating to proceed with the functions to establish a connection to the busy line.' Instead the operation `of the holding magnet 21 closes a connection to lead 54 directly from ground and contacts of the holding magnet 23,v contacts of the holding magnet 21, lead 55 to operate a relay in the marker circuit. This relay now causes the selection and Vconnectionoi an idle ringing and coin control circuit through a ringing circuit connector switch to the link 24 and causes the ringing of the desired called party over this link 24 in accordance with the code selected. When the subscriber answers this code ringing, a ringing trip relay in the ringing circuit operates and the established connections are releasedV causing the holding ground over the sleeve conductor through the call originating switch CO to be removed. Magnet 23 thereby releases causing the operation of the line relay 34 which holds the magnet 21 operated as this magnet is slow to release. The absence of ground on lead 5i indicating that the line is busy and relay 34 and magnet 21 are maintained operated until the subscribers hang upV their receivers. Y

What is claimed is:

1. In a telephone system, lines, a call originating switch having a holding magnet for each line, a call terminating switch having a holding magnet for each line, said lines appearing in both of said switches, linking circuits, means responsive to a line when calling for operating said originating switch and the holding magnet of both switches for said calling line for extending a connection from said calling line to an idle linking circuit, and means for operating said terminating switch for eastablishing a connection from said seized linking circuit to a called line and for operating the holding magnets of both switches for said called line.

2. In a telephone system, lines, a call originating switch having a holding magnet for each line, a call terminating switch having a holding magnet for each line, said lines appearing in both of said switches, linking circuits, means responsive to a line when calling for operating said call originating switch and the holding magnet of both switches. for said calling line for extending a connection from said calling line to an idle linking circuit, means for operating said terminating switch to extend a connection from said seized linking circuit to a called line and causing the operation of the holding magnet of the called line in the call terminating switch to operate by rst causing the associated holding magnet in the call originating switch to operate.

3. In a telephone system, lines, linking circuits, cross-bar switches for extending connections between a calling line and a called line over a 4linking circuit and including a holding magnet for holding a connection over a call originating switch from a calling line to a linking circuit and a holding magnet for holding a connection over a call terminating switch from Aa linking circuit to a called line, means responsive to the seizure of a calling line for connecting said calling line to an idle linking circuit over a call originating switch and operating the holding magnet in said call originating switch and in response to the operation of said magnet for operating the holding magnet in the associated call terminating switch for said calling line, and means responsive to dial pulses received from the calling line for connecting a called line to the seized linking circuit over a call terminating swit-ch and for operating the holding magnet of the associated call originating switch and in response to the operation of said holding magnet for operating the holding magnet in the said call terminating switch.

4. In a telephone system, an originating switch, a terminating switch, a line appearing in both of said switches, means responsive to said line when calling for operating said originating switch to extend a connection from said line, means for operating said terminating switch to extend a connection to said line when called, means effective while said line is in a calling condition for releasing said originating switch to release the connection extended from said line, and means including said terminating switch for preventing said calling line from causing the reoperation of said originating switch.

5. In a telephone system, an originating switch, a terminating switch, a line appearing in both of said switches, a line relay individual to said line and normally connected thereto, means controlled by said relay when said line is calling for operating said originating switch to extend a connection from said line, means for disconnecting said relay from said line, means for operating said terminating switch to extend a connection to said line when called, means for releasing said originating switch to release the cennection extended from said line and for reconnecting said line relay to the line, and means including said terminating switch for preventing said line relay from causing the reoperation of said originating switch.

6. In a telephone system, an originating switch having an operating magnet, a terminating switch having an operating magnet, a line appearing in both of said switches, a line relay individual to said line and normally connected thereto, means responsive to the operation of said line relay when said line is calling for causing the operation of the magnet of said originating switch to extend a connection from said line and to disconnect said line relay from said line, means for operating the magnet of said terminating switch to extend a connection to said line when called, means for releasing the magnet of said originating switch to release the connection extended from said line and to reconnect the line relay to said line, and means controlled by the magnet of said terminating switch for preventing the reoperation of the line relay from initiating the reoperation of said originating switch.

7. In a telephone system, lines, linking circuits, cross-bar switches for extending connections between a calling line and a called lino over linking circuits and including a holding magnet for holding a connection over a call originating cross-bar switch from a calling line to a linking circuit and a holding magnet for holding a connection over a call terminating crossbar switch from a linking circuit to a called line and in which all lines terminate in both the call originating and call terminating switches, means responsive to the seizure of a calling line for connecting it to an idle linking circuit over a call originating switch and operating both associated holding magnets, means responsive to dial pulses received from said calling line for connecting a called line to the seized linking circuit over a call terminating cross-har switch and operating both associated holding magnets, and means controlled by the two first mentioned holding magnets when the connection is established from the calling line to a linking circuit over the call originating switch for releasing said call originating switch to release said linking circuit from the calling line if the connection to the ycalled line is not completed within a certain interval after the connection was extended from the calling line to said linking circuit and for preventing the reoperation of said call originating switch to seize another linking circuit by the calling line.

8. In a telephone system, lines, linking circuits, cross-bar switches including a call originating line switch for extending connections from a calling line to a linking circuit and a call terminating line switch for extending connections from a linking circuit to a called line, said switches also including selecting magnets for selecting linking circuits and holding magnets for selecting calling lines and called lines in said two types of switches respectively, means operative on the seizure of a calling line for operating a select magnet in the call originating switch and the holding magnet for the calling line in said call originating switch and the helding magnet in the corresponding call terminating switch for seizing a linking cirmiit in said call originating switch, means responsive te dial pulses received over the calling line for operating a select magnet in the call terminating switch and the holding magnet of the call line in the call originating switch and the holding magnet in the corresponding call terminating switch for establishing a connection between a seized linking circuit and the called line, a permanent signal arrangement operative in case the calling line subscriber fails to complete the connection to a called line within a certain time interval after the connection has extended through the call originating switch to a linking circuit, said arrangement being controlled -by the two operated holding magnets to release the call originating switch and to prevent the calling subsscribers line from initiating another call.

9. In a telephone system, lines, linking circuits, cross-bar switches including call originating line switches for extending connections from calling lines to linking circuits and call terminating line switches for extending connections from linking circuits to called lines, said switches also including selecting magnets for selecting linking circuits and holding magnets for selecting calling lines and called lines in said two types ci switches, respectively, means operative on the seizure of a calling line for operating a select magnet in a call originating switch and the holding magnet for the calling line in said call originating switch and the holding magnet in the corresponding call terminating switch for seizing a linking circuit in said call originating switch, means responsive to dial pulses received over the calling line for operating a select magnet in a call terminating switch and the holding magnet of the called line in the corresponding call originating switch and the holding magnet in the corresponding call terminating switch for establishing a connection between a seized linking circuit and the called line, a permanent signal arrangement for releasing the holding magnet for the call originating switch to release the calling line from the seized linking circuit operative if the calling line subscriber fails to complete the connection to a called line within a certain interval after the seizure of the linking circuit and means controlled on the release of said holding magnet for maintaining the holding magnet in the corresponding call terminating switch operated and for thereby preventing the calling line from initiating another call.

10. In a telephone system, lines, linking circuits, cross-bar switches including call originating line switches for extending connections from calling lines to linking circuits and call terminating line switches for extending connections from linking circuits to called lines, said switches also including selecting magnets for selecting linking circuits and holding magnets for selecting calling lines and called lines in said two types of switches, respectively, a line relay for each line, means responsive to the seizure of a calling line for operating the corresponding line relay, means controlled by said relay when operated for operating a selecting magnet in a call originating switch and the holding magnet for said calling line in said call originating switch and the holding magnet in the corresponding call terminating switch for seizing a linking circut by said call originating switch and for releasing the line relay when said connection is established, means responsive to dial pulses received over the calling line for operating a select magnet of a call terminating switch and the holding magnet of the called line in the corresponding call originating switch and the holding magnet in the corresponding call terminating switch for establishing a connection between a seized linking circuit and a called line, a permanent signal arrangement for releasing the holding magnet for the call originating switch'to release the calling line from the seized linking circuit operative in case the calling line subscriber fails to complete the connection to a called line a certain interval after the connection was extended through the call originating switch to a linking circuit, and to reoperate the line relay to maintain the holding magnet of the corresponding call terminating switch operated and for thereby preventing the calling line from initiating another call.

11. In a telephone system, an originating switch, a terminating switch, a party line appearing in both switches, means responsive to said line when a party thereon is calling another party on the same line for operating said originating switch to extend a connection from said line and causing the ringing code of the called party to be transmitted over said connection to the line and means including the terminating switch operative when the called subscriber answers for releasing said originating switch to terminate the ringing and to release the connection extending from said line and for preventing said party line as long as it is engaged by the calling subscriber andcalled subscriber from causing the reoperation of said originating switch.

12. In a telephone system an originating switch, a terminating switch, a party line appearing in both switches, a line relay individual to said line and normally connected thereto, means controlled by said relay when a subscribed on said line is calling another subscribed on the same line for operating said originating switch to extend a connection from said line and to ring said other subscriber and for disconnecting said relay from said line, means for releasing said originating switch to release the connection extended from said line to stop the ringing and connect said line relay to the line when the called subscriber answers, and means including said terminating switch for preventing said line relay from causing the reoperation of said originating switch.

13. In a telephone system, an originating switch, a terminating switch, lines appearing in both. switches, some of said lines being party lines, means responsive to a call from any one of said lines for operating said originating switch to extend a connection from said line and for yoperating said terminating switch to extend a connection to a single line when called, means operated when a subscriber on a party line is calling another subscriber on said party line for ringing said other party over the connection extended through said originating switch, means eiective while a single line is in calling condition or when the called subscriber answers on a call from one subscriber to another on a party line for releasing the originating switch, and means including the terminating switch for preventing the subscriber of the calling line or the calling subscriber and called subscriber on 'a party line from causing the reoperation of the originating switch.

14. In a telephone system, an originating switch, a terminating switch, lines appearing in both of said switches, some of said lines being party lines, line relays individual to each line normally connected thereto, means controlled by a line relay when a single line is calling to operate said originating switch to extend a connection from said line, means controlled by a line relay when the subscriber on a party line is calling another subscriber on the same line for operating said originating switch to extend a connection from said party line and causing the ringing code of the called party on said party line to be transmitted back over said connection from the party line through' the call originating switch, means for disconnecting a line relay from a line whether it is a single or a party line, means for releasing said originating switch to release the connection from a calling line when it is a single or a party line and means including said terminating switch for preVenting a line relay of a single or a party line from causing the reoperation of said originating switch.

15. In a telephone system, lines, some of which are party lines, a call originating switch having a holding magnet for each line, a call terminating switch having a holding magnet for each line, said lines appearing in both of said switches, linking circuits, means responsive to lines when calling for operating said originating switch and the holding magnet of both switches for extending a connection from said calling to an idle linking circuit, means for operating said terminating switch for establishing a connecs,

tion from said seized linking circuit to the subscriber on a called line if the subscriber on said called line is not on th'e same line as the subscriber on the calling line and for operating the holding magnet of both switches for said called line, means operative if a called subscriber is on the same party line as the calling subscriber when said line is calling for operating the call 'originating switch and the holding magnets of both switches to extend a connection to an idle linking circuit and causing the ringing code of the called subscriber on said party line to be transmitted back over said seized linking circuit through the call originating switch to the party line, means operated when the called party line subscriber answers, and for releasing said connection to an idle linking circuit by the release of the holding magnet in the call originating switch and for holding the holding magnet of the call terminating switch operated to prevent the reoperation of the call originating switch until the calling subscriber and the called subscriber on said party line releases the connection and means operative if the calling subscriber fails to complete a call for releasing the connection to an idle linking circuit by the release of the holding magnet on the call originating switch and for holding the holding magnet of the called terminating switch operative to prevent the reoperation of the call originating switch until the calling subscriber releases the connection EDSON L. ERWIN.

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