US2209777A - Telephone system - Google Patents

Description

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u -FF GR. MM #SamxtW w M KM u 5 w. A RR w W m M. m w W Patented July 30, 1940 PATENT OFFICE TELEPHONE SYSTEM Ralph E. King, Short Hills, and Ohmer R. Miller, Morristown, N. J., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application December 1, 1938, Serial No. 243,348

21 Claims.

This invention relates to telephone systems and particularly to systems comprising toll offices and automatic switching means for completing toll calls.

It is the object of the invention to minimize the number of manual switching operations involved in establishing toll connections, to expedite the completion of such connections, and to more efficiently and reliably effect the transmission of directive and supervisory signals to and through the automatic switching means employed in completing desired connections.

One of the features of this invention is a telephone system comprising toll ofiices in which automatic switches are provided for routing incoming calls to called toll and local oflices, the talking conductors of one or more of the trunk and selector circuits constituting a simplex circuit for controlling the operation of a relay bridged across one end of these talking conductors, supervisory signals being transmitted from a connected outgoing line or trunk to the incoming line over a non-talking conductor other than the usual sleeve or test conductor. The relay is operated due to an unbalance between the two sides of the simplex circuit when the outgoing line or trunk to which the connection is extended is of such a character as to require that the transmission pads associated with the incoming line be included in the talking circuit, If two lines, each provided with transmission pads, are connected together, the simplex circuit comprising the talking conductors of the connection is used to control the transmission pads of both lines, one relay being bridged across the talking conductors at one end of the simplex and another relay being bridged across the talking conductors at the other end of the simplex.

Another feature of the invention is the provision of a non-talking conductor between an incoming line and a connected outgoing line for transmitting supervisory signals from' the outgoing line or trunk to the incoming line in combination with the provision of a simplex .circuit over the talking conductors of the connection for transmitting supervisory signals from the incoming line to the outgoing line or trunk, and for controlling the short-circuiting of the transmission pads associated with the incoming line.

Another feature of the invention is a circuit arrangement whereby a calling toll operator, v

;, during the completion of a connection from an incoming line to a desired toll operator or local subscriber under the control of the calling operators dial, will receive a stop-dialing signal whenever the connection is extended to a trunk which is not at the time of seizure ready to receive dial impulses, and will receive a startdialing signal as soon as dialing may be resumed. According to this feature a toll route selector is arranged to transmit a stop-dialing signal to a calling operator as soon as the brushes are selectively advanced to a group in which each of the trunks is connected to an impulse receiver in response to seizure of the trunk, the stop-dialing signal being continued by the seized trunk circuit until an impulse receiver is associated therewith. In a case where the impulses are being transmitted by a register sender, the stop dial signal can-be used to stop the sending of impulses until the stop-dialing signal ends.

According to a further feature, the dial pilot lamp in an operators dial circuit is arranged to respond to supervisory signals, including a stopdialing signal, received by the associated outgoing trunk circuit while the dial circuit is connected to the trunk, the disconnection of the dial circuit being effected only upon restoration of the dial key.

Another feature of the invention is the provision, in a toll oflice comprising selector switches for extending connections from incoming lines to outgoing trunks, including t1 unks to community dial oflices in which impulse responsive apparatus is connected to a trunk as a result of its seizure, and to lines including ring-down toll lines, of supervisory signaling means individual to each selector having access tosuch trunks and lines for establishing the required signaling and supervisory circuits depending upon the character 'of a selected line or trunk.

These and other features of the invention will be further explained by considering their application in the telephone system shown schematically in the drawings of this specification. The

'invention is, however, not limited in its application to the system shown in the drawings and is generally applicable to toll systems comprising selector switches for establishing connections including interoflice trunks.

Referring to the drawings:

Fig. 1 shows a toll operators cord Cl and operators telephone;

Fig. 2 shows a toll operator's position dial circuit PDI; I

Figs. 3 and 4 .show outgoing jacks J I, J2, answeringjacks J3, J4, and an outgoing trunk circuit OT] connected to jack-J l Fig. 5 shows intertoll selectors TS I and'TS3, an interswitch trunk. circuit ISTI and an assoelated auxiliary intertoll selector ASI, an incoming trunk circuit ITI connected to jack J3 of Fig. 4, an intertoll trunk T3 with its associated composite signaling circuit CS3, two-way trunk circuit TWT3 and outgoing trunk circuit 0T3 connected to jack J2 of Fig. 3;

Fig. 6 shows a composite signaling circuit CSI connecting trunk circuit OTI of Fig. 3 to one end of intertoll trunk TI;

Fig. 6A shows a two-way trunk circuit TWTI connecting trunk circuit OTI of Fig. 3 to the toll route selector T81 of Fig. 5;

Fig. 7 shows a composite signaling circuit CS2 at the other end of intertoll trunk TI Fig. 7A shows a two-way trunk circuit TWT2;

Fig. 8 shows toll route selector TS2 associated with the two-way trunk circuit TWT2 of Fig. 7 and toll route selector TS4 associated with the two-way trunk circuit TWTQ of Fig. 9;

Fig. 9 shows outgoing Jacks J5 and J6 and an outgoing trunk circuit 0T2 connecting jack J5 to the composite signaling circuit CS2 of Fig. 7 and trunk circuit TWT2 of Fig. 7A; Fig. 9 also shows an outgoing trunk circuit 0T4 connecting jack J 6 to the associated two-way trunk circuit TWT4 and through the composite signaling circuit CS4 to an intertoll trunk T4;

Fig, 10 shows answering jacks J7 and J8, an incoming trunk circuit IT2 connecting jack J1 to a set of terminals in the bank of selector AS2 of Fig. 14;

Fig. 11 shows an interswitch trunk circuit IST2 connected to sets of terminals in the banks of selectors T82 and T54 of Fig. 8;

Fig. 12 shows an operators position circuit PC2 and a cord circuit C2 for connection with jacks J5, J6, J1, J8, J3, Jill, JH and JI2 .of Figs. 9, 10, 15 and 16;

Fig. 13 shows a dial circuit DC2 associated with the position circuit PC2 of Fig. 12;

Fig. 14 shows an auxiliary toll route selector AS2 connected to the trunk circuit IST2 of Fig. 11;

Fig. 15 shows a ring-down toll line circuit EDI and jacks J9 and J l0 associated with a ring-down toll line RDL;

Figs. 16 and 17 show a two-way trunk circuit CDTI connecting one end of a trunk CDT to terminals in the bank of selector AS2 of Fig. 14;

Fig. 18 shows "a two-way trunk circuit CDT2 in a community dial oifice at the other end of trunk CDT, a trunk finder TF and incoming selector IS, a connector C, a line finder LFI and first selectorSl, and two subscribers stations A and B; and

Fig. 19 shows the relative position of each of Figs. 1 to 18, inclusive, to form an intertoll dialing system embodying the features of the invention.

The system represented in the drawings includes a plurality of toll oflices, each of which comprises a toll board with operators positions and cords for answering calls incoming from local manual or dial ofiices, from toll subscribers lines, from community dial omces, or from other toll offices and for extending an incoming call to a switching trunk leading to it called manual or dial local oflice, to a called toll subscriber's line, to a community dial oflice, or to an intertoll trunk. Ouigoing jacks connect to switching trunks, toll ines, trunks to community dial offices, and intertoll trunks. Answering jacks are directly connected to recording trunks, toll subscribers lines, trunks from community dial oillces, and intertoll trunks. 'I'oll route selector and auxiliary toll route selectors are provided for use on calls incoming over intertoll trunks to establish connections with called toll, local, or community dial ofi'ices. The operators positions are provided with dials for use in controlling the operation of incoming and auxiliary toll route selectors in other toll ofiices and for controlling the operation of selector and connector switches in local or community dial ofiices. While not shown in the drawings, the operators positions may be provided with key-sets in place of dials, in which case senders are associated with the outgoingv trunks to register the key-set impulses and control the selectors.

The toll board in one toll office is represented by an operators cord Cl and position dial circuit PDI, the outgoing jacks J l and J2 and the answering jacks J3 and J4. The jack J I, outgoing trunk OTI, two-way trunk circuit TWTI, incoming toll route selector TSI, and the composite signaling circuit CSI are all associated with a two-way intertoll trunk Tl, the distant end of which terminates in a second toll office. The

jack J2, outgoing trunk circuit 0T3, two-way trunk circuit TWT3, incoming toll route selector TS3 and composite signaling circuit CS3 are all associated with a two-way intertoll trunk T3, the distant end of which terminates in a third toll oflice. The incoming toll route selectors, such as TSI and T53, have access to auxiliary toll route selectors. The auxiliary route selectors, such as ASI, have access to toll lines, intertoll trunks, switching trunks leading to the local ofiices, trunks leading to community dial ofiices, and to incoming trunk circuits terminating at a toll operators positions, such for instance, as the trunk circuit ITI connecting to answering jack J3. Interswitch trunk circuits such as ISTI are associated with auxiliary route selectors having access to ring-down toll lines or to community dial oflices of the link type, that is, ofiices in which impulse responsive apparatus is connected to a trunk in response to its seizure at the toll oflice.

The toll board in the second toll ofiice is represented by the operators cord C2, position circuit PC2, dial circuit D02, and jacks J5 to Jl2, inclusive. The jack J 5, outgoing trunk circuit 0T2, two-way trunk circuit TWT2, incoming toll route selector TS2, and composite signaling circuit CS2 are all associated with the intertoll trunk Tl connecting with the first toll oflice. The jack J 6. outgoing trunk circuit 0T4, two-way trunk circuit TWT4, incoming toll route selector T84 and composite signaling circuit CS4 are all associated with an intertoll trunk T4 leading to a fourth toll office. The incoming toll route selectors T52 and T84 have access to auxiliary toll route selectors. The auxiliary selectors, such as AS2, have access to tell lines, intertoll trunks, switching trunks leading to local oflices, trunks to community dial oilices and to incoming trunk circuits such as IT2 connecting to answering jack J'L. Interswitch trunk circuit IST2 is individual to the auxiliary selector AS2 which has access to both ring-down lines such as RDL and trunks, such as CDT, to community dial ofilces of the link type.

The outgoing trunk circuits OTI and GT2, incoming two-way trunk circuits TWTI and TWT2, toll route selector circuit TS2, interswitch trunk circuit IST2, auxiliary toll route selector A82, incoming trunk circuit IT2, ring-down toll line circuit RDI, and community dial oflicetrunk circults CDTI and CDTZ are all shown in detail. 75

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