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Патент USA US2277600

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March 24, 1942.
.1_ B, MCKIM
Filed Jan. 5, 1940
11 Sheets-Sheet 1
March 24, 1942.y \
Filed Jan. 5, 1940
11 sheets-sheet 2
By J. B. Mc KIM
March 24, 1942.
J, B, McK|M
Filed Jan. 5, 1940
11 Sheets-Sheet 3
March 24, 1942.
2,217,600 Í
Filed Jan; 5J,- 1940
11 Sheets-Sheet 4
J5. Mc K/M‘
"W [email protected]
'March 24, 1942.
_1_ B. McKlM
Filed Jan. A5, 1940
11 sheets-sheet 5
/N VEA/ron
J. B. Mc K/M
March 24, 1942.
J. B. _MMM .
Filed Jan. 5, 1940
_ 11 sheèts-,shee't 6_
y .
[email protected]
March 24, 1942.
J. E3.lWC|<|hd
Filed Jan. 5, 1940
11 Sheets-Sheet 7
y J B. Mc K/M
March 24, 1942.
J. B. McKlM
2,277,600 v
Filed Jan. 5, 1940
1l Sheets-Sheet 8
//v VEA/Tok
J. B. Mc KIM
March 24, 1942.
Filed Jan. 5, 194C
11 Sheets-Sheet 9
J. B. Mc KIM
~March 24, 1942. .
` J, B,A McklM
Filed Jan. 5, 1940 f
11 Sheets-Sheet ¿10
_nwe/v TOR
March 24, 1942.`
¿_ Bl, McKlM
Filed Jan. 5, 1940
11 sheets-sheet 11
Patented Mar. 24, 1942
James. B. McKim, Newv York,y N. Y., assignor to
Bell Telephone Laboratories, Incorporated, New
York, N. Y., a corporation of New York
Application January 5, 1940, Serial No. 312,468 v
l0 Claims.
This invention relates to telephone systems and
more particularly to switching systems for auto
matically connecting units of equipment together
for telephone connections and supervision.
Switching systems which are automatically re
sponsive to incoming telephone calls have in
cluded link structures for connecting units of
equipment together which serve either as trans
mission paths or for setting equipment for com
pleting a telephone connection. Links used for
transmission paths for telephone connections are
held in place for the duration of the telephone
connection. Other links used for temporarily
(Cl. 179-27)
sponsive to the signals registered in the control
Another and related feature'is in a system yof
automatically controlling the locking or releas
`_ ing «of the link and channel by transmitting class
l0 -
signals from the trunk line to the control unit,
responsive to the connection of the link to the
position channel and responsive to the connec
tion of the control unit to the position circuit.
Another and related feature is a'system for
manually controlling the locking of the link and
channel to the trunk line connection for the
duration ofthe call or releasing the link and
connecting units of equipment together have been
channel therefrom.
released' after the connected equipments have
completed their functions in setting switches or
other units of equipment for completing a tele
phone connection. In the latter method of op
eration it is often necessary to recall the services
These and other features will be discussed more
fully in the following description.
To illustratethe features of the invention ref
erence may be ,hadto the accompanying draw
ings in which:
1 Figs. 1 toV 11’, inclusive, when arranged as in
dicated in Fig. 12 show the detailed structure in
of the same link or a link of like structure in the
same group of links one or more times for super
visory purposes after a telephone connection has
been completed. The selection and operation of
links for supervisory purposes constitute a delay
in the continuity of telephone service which with
the present invention may be avoided.`
An object of this invention is, therefore, t0
' which a link' and channel may be'locked to the
apparatus involved in a telephone connection for
supervisory purposes ;y
v Figs. land 2 illustrate a distant calling toll
' oflice, an incoming trunk, an outgoing trunk, a
plurality of switches- for connecting incoming
and= outgoing trunks and a distant called toll
provide channels including a link between the
equipments involved in a telephone connection
rconnecting calling incoming trunks and link
switchesA to aflink-control circuit shown in Fig. 6;
f Fig. 4 illustrates the operator’s positionchan
, Figs, 7, 10 and 11 illustrate a cordless toll op
pervision from this operator’s position.
erator’s position circuit;
A feature of this invention is in a system of
control circuit;
to an incoming call over a trunk line for connect
ing the trunk line to a channel in an operator’s
Fig. 9 diagrammatically illustrates an oper
ator’s position sender, a connector for connect
ing such sendersïto one of a plurality of markers
and the apparatus of a marker which may be
position, in connecting the incoming trunk line
to an outgoing trunk line and in controlling the
locking or releasing of the link and channel re
used to disclose the invention.
sponsive to signals registering the class of the
incoming and the outgoing trunk lines involved
Another and related feature of this invention
is in a system of selecting and operating an idle
link responsive to an incoming call over a trunk
line for connecting the trunk line to a channel
connection and in automatically controlling the
The trunks incoming to a toll office vary in
transmission characteristics and also vary in
character. Via or terminal ringdom trunks in
coming from a distant toll ofñce operate from
in an operator’s position, in transmitting signals ‘ `alternating
current signals.
between the trunk line and the position channel,
in setting a control unit from the operator’s posi
tion for automatically completing a telephone
, Figs. 5 and 8 illustrate a cordless toll position
selecting and operating an idle link responsive
in the telephone connections.
Fig. 3 illustrates a- link and a connector for
and an operator’s position, which may be auto
matically or manually locked for supervision of
particular classes of telephone connections and
automatically or manually released when the
class of the telephone connection requires no su
Other toll offices
may use the straightforward trunking system
transmitting direct current signals for energiz
ing the incoming ktrunks of a distant office.
Other trunks are known as dial intertoll trunks
locking or releasing of the link and channel re- f . which are operated from pulse transmitting sys
tems for automatically operating apparatus in a
machine switching office. In view of this the
trunks involved in a toll connection require dif
ferent class of service signaling means depending
upon the character of the trunk. Signal trans
mitting apparatus is included in each such trunk
for indicating to the associated apparatus of an
automatically operable toll office, the character
ofthe trunk connected to this apparatus in order
energizes a marker connector 90| for associat
ing an idle marker therewith which receives code
registrations from the sender covering the dis
tant toll office or station to which the call
should be routed, the character of the trunk
lines, the class of the call and the character and
class of the incoming trunk line. The registra
tions are used for selecting an outgoing trunk of
a particular routing having the characteristics
that the same character of trunks shall or shall 10 required for the type line connection to be made.
not be connected together for transmission pur
poses, and in order that it shall be determined
whether supervision of the telephone connection
Circuit combinations are made in the marker
by apparatus operated in accordance with the
foregoing registrations which control operations
in the sender and the position control circuit when
is required. The same or diiîerent characters
of intertoll trunks are connected together de 15 the marker is in the process of releasing. The
circuits >energized determine whether a link and
pending upon the length of the interconnected
channel is to be connected between the incom
toll trunks for completing a telephone connection.
ing trunk and position channel apparatus for
It is therefore necessary that the connecting
the duration of the telephone conversation or
apparatus be guided in the matter of class of
intertoll trunk and the transmission character 20 whether this apparatus shall be released. When
supervision is to be maintained over a telephone
istics of both interconnected trunks. In the sys
connection during the period of conversation,
tem disclosed, such information is automatically
circuits are established in the position control
available responsive to the connection of an in
circuit for energizing a particular relay in the
coming trunk with the connecting apparatus and
responsive to the registrations for selecting an 25 incoming trunk circuit. The energization of the
latter relay establishes a locking path for the
outgoing trunk to a local or distant office.
link and a locking path for particular apparatus
A call from a distant oflice actuates the appa
in one channel of the position which is associated
ratus of the receiving toll oiiice by signals, which
with this link connection. The position channel
automatically energize the apparatus of a link
for connecting the intertoll trunk such as dis 30 and the link is thus locked for maintaining
supervision of the telephone connection. Ener
closed in Figs. 1 and 2 with a cordless toll oper
gization 0f apparatus in the position control cir
ator’s position, such as disclosed in Figs. '7, 10
cuit by a circuit combination in the marker also
and 11. An idle link channel is chosen by the
energizes a. relay in the incoming trunk when no
energization of the link-control circuit of Fig. 6
which selects an idle channel, Fig. 4, entering 35 supervision is required. In this case the chan
nel and link switches are released and may be
one of a plurality of cordless toll operators’ posi
associated with other incoming trunks for serv
tions. There are ordinarily a plurality of chan
nels entering each position. Each channel is
ing other incoming calls. When the link is
locked to a channel, only one relay in the chan
connected to a secondary link switch, such as
switches 302 or 303. These are interconnected 40 nel is kept _operated for associating signal paths
to a plurality of primary link switches available
to the calling incoming trunks. By means of
cross-wiring these secondary switches may be
associated through one of a plurality of primary
switches with the calling incoming trunk thus 45
an idle channel of a position may be actuated
by the link-control circuit, Fig. 6, and connected
between the position and the incoming trunk cir
cuit so that the toll operator’s position signals
may be actuated at any time when either the
calling or called parties require the attention of
the cordless toll operator.
In addition to the arrangement for locking a
link and channel automatically from the marker,
a second arrangement is used for locking the
link and channel manually by the energization
by the link-control circuit. The operation of 50 of a position key which energizes relays accom
plishing the result manually which is accom
the link switches connects the apparatus of the
plished automatically by the marker. The actual
channel with the apparatus of the calling in
locking of the link is only accomplished after
coming trunk circuit causing the energization of
the marker has completed the selection of the
apparatus in both the channel circuit and the
calling incoming trunk circuit. The energiza 55 outgoing trunk and set the switches for the
connection between this outgoing trunk and the
tion of this apparatus is successively interacting
incoming trunk. As before, the marker in the
which adjusts the incoming intertoll trunk cir
process of releasing energizes apparatus which
cuit, Figs. 1 and 2, and adjusts the apparatus
completes circuits for locking the link by the
of the channel, Fig. 4, and the position apparatus,
Figs. "I, l0 and l1, for successive cooperative sig 60 energization of particular relays in the position
control circuits. This manner of locking the
nals. The apparatus of the channel and posi
link manually is placed under the control of the
tion circuit is adjusted for receiving class of
marker in order that apparatus operations take
trunk line signals from the incoming trunk cir
place in proper sequence.
cuit. The incoming trunk circuit is adjusted
for transmitting these signals. The operation of 65
the position apparatus progresses to a point
In the present disclosure the distant office
where signals are given to the cordless toll oper
|00 is connected to the automatically op
ator including a tone signal to indicate to this
erable toll cnice illustrated in the drawings Figs.
operator the character of call to be answered.
The apparatus of the position control circuit, 70 1 to 1l, inclusive, by a ringdown intertoll trunk
which is energized by transmitting ringing cur
Figs. 5 and 8, is energized including a start cir
rent from office |00 over conductors |35 and |36
cuit for the sender 900. Registrations are made
to the incoming trunk, Figs. 1 and 2. After the
in the sender by the cordless toll operator ac
distant operator in office |00 has completed set
cording to code designations given to her by
ting apparatus for the connection, this ringing
the Acalling party at station | 00. The sender
by this link-control circuit through a secondary
and primary link switch which are also actuated
current is applied .automatically or manually to
conductors |35 and |30 which is transmitted
through the winding of alternating current relay
|03 energizing this relay. The energization of
relay |03 releases relay |04 which is normally
energized from battery through its winding to
ground on the contact of relay |03. _The re
lease of relay |04 establishes a circuit for op
erating the incoming trunk relay 202 over a cir
tion to which this channel is connected. In
view of the fact that each channel is connected
to a different horizontal level of secondary
switches, such a's 302 and 303, the test of the
channel determines the secondary switch to be
used. Each incoming trunk appears on at least
one horizontal level oi‘. a primary linkv switch
which may be reached from different secondary
link switches through diiîerent verticals on this
cuit from battery through the winding of relay l0 primary link switch. The hold magnets for the
primary and secondary switches, which consti
202, contact 2 of relay |04, contact 1 of relay
tute a channel, are connected in multiple as
||1, contact 6 of relay 203 to ground. Relay
shown and operate together. An idle channel in
202 in operating establishes a locking circuit for
a position having an operator in attendance has
itself through its contact 3, contact 1 of relay
||1 to ground through contact 0 of relay 203. 15 battery on lead 340 and ground on lead 34|.
Ground is placed on lead 34| by the operation of
When ringing current is disengaged from the
relay 40|I actuated when relay 10| is actuated.
trunk conductors |35 and |36', relay |03 releases
Relay 10| is only actuated when an operator is
which reenergizes relay |04. A circuit is thus
servingv the cordless position. The circuit for
established for- relay ||3 from battery through
its winding, contact 5 of relay M2, contact 2 of 20 relay 10| may, thus, be traced from battery
through its winding, contact | oi individual
relay |04, contact 3 of relay 202, contact 1 of
channel relays 42|, 420 and 402 normal,.jack
relay | |1, contact 0 of relay 203 to ground. Re
H04 which has its contact closed when the
lay ||3 is locked through contact 4 of relay
telephone operator’s headset plug | |00 is inserted
20|, contact 5 of relay H3 to its operat
ing ground on contact 6 of relay 203. The 25 therein, key 505, to ground on contact | of relay
operation of relay ||3 now establishes a start
circuit for a link which associated the incoming
trunk and the operator at ofñce |00 with the
Relay 40| has as many contacts thereon as
there are channels in the position and, there
fore, its operation makes all channels idle which
are not in use. The release of this relay makes
cordless operator Whose telephone apparatus is
shown in Fig. 11 of this disclosure. This link 30 all channels busy. This will be seen fromthe
description of the channel apparatus.
start circuit may be traced from ground on con
tact | of relay ||4 through contact 2 of relay
Link and Zink-control circuit
H3, contact | of relay ||2, lead 320, contact of
The link-control circuit, Fig. 6, is used for se
relay 3|2, winding of link-start relay 3| i to bat
tery. The link-connector and link-control cir 35 lecting an idle channel from a large plurality of
channels entering cordless toll positions. The
cuit is shown diagrammatically and reference is
control circuit is associated with channels which
made to the patent application to King et al.
are connected to certain levels of the secondary
Serial No. 295,010, iiled September 15, 1939 is
sued as Patent No. 2,236,246, March 25, 1941 or ` cross-bar switches shown in the right-hand por
the patent application to Busch et al. Serial No. 40 tion of' Fig. 3. These control circuits are in an
incoming group arranged to serve the calling
295,012, filed September 15, 1939, for a com
incoming trunks for testing the channels of the
plete disclosure of this link-connector and link
position and operating switches which connect a
control circuit.
calling incoming trunk with an idle channel.
Link connector
45 The operation of start relay 3|| establishes cir
cuits for energizing a connector unit for control
The energization of the link-start relay 39|
~ establishes an obvious circuit for a link-con
ling the association of'a calling incoming trunk
with an idle link-control circuit. The switches
300 and 30| comprise a portion of a primary link
ticontact relay such as `3|1 for connecting a large
number of leads from an idle link-control cir 50 switch. Each switch of vthis character ordinarily
nector selecting relay 3|@ which operates a mul- '
cuit, Fig. 6, to the incoming trunk circuit, Fig. l
Aand Fig. 2, to a plurality of toll positions, Fig. 4,
has ten separate levels and a large plurality of
verticals. In this instance only one is shown
which is arranged to connected the calling in
coming trunk to a secondary switch by the oper
and to a plurality of switches, Fig. 3. There are
a plurality of link-control circuits, Fig. 6, which
are small compared to the large number of 55 ation of a select magnet and a hold magnet. In
switches, Fig. 3, and the large number of posi
tion channels, Fig. 4. Consequently, as noted
in the aforementioned patent applications, it is
necessary for a link connector to ñnd an idle link
practice the incoming trunk may be associated
with Various secondary switches 302 and 303
through a number of different verticals on the
primary switch, making a large plurality of
control circuit before operating the multi'contact 60 choices of apparatus for extending a, call from
the incoming trunk to the apparatus of the chan
relay 3|1 to connect these different units to
nels in the toll o?lice switchboard. The second
gether. The switches 300 and 30! represent a
ary switches 302 and 303 may be on a single cross
single horizontal level in two verticals of a pri
bar switch or on separate cross-bar switches de
mary link cross-bar switch connected to an in
coming trunk circuit. Switches 302 and 303 are 65 pending upon the choice of connection which is
best suited for use. The secondary switch points
known as secondary switches of which there are
shown may therefore‘be considered as one level
a large plurality connected to a largevplurality
of any vertical on a single cross-bar switch or
of channels in a plurality of cordless toll posi
one level of a vertical on any of a plurality of
tions. The ones shown are diiîerent horizontal
levels on diiïerent verticals of the same or dif 70 cross-bar switches.
The multicontact relay 3|3 and the multicon
ferent cross-bar switches. The function of the
link-control circuit is to test a plurality of chan
nels associated with a plurality of cordless toll
positions to obtain an idle channel and the
tact relay 3|1 and the relays shown in the lower
portion of Fig. Sconstitute an arrangement for
giving an incoming trunk a plurality of choices,
services of the toll operator in the cordless posi 75 in obtaining the services of a link-control cir
cuit, Fig. 6, which may be associated therewith
by the operation of the multicontact relay 311.
The control circuit associated with a relay, such
as 311, must test idle before it is seized. There
are a plurality of multicontact relays 313 for each
incoming trunk circuit. This plurality of relays
are connected to a plurality of relays 311 which
are interconnected when strapped as shown.
There are a plurality of relays, such as 311, for
each connector extending between the contacts of
relays 313 and 31'1. Each control circuit has a
representative relay in each connector so that
any one of the control circuits may be associ~
ated when idle with any of the connectors be
tween a group of trunks and the control cir
cuits. The operation of start relay 311 by a cir
cuit as previously established from the incoming
trunk initiates the selection of an idle control
circuit. -A circuit is first established from bat
tery through resistance 310, contact of start re
lay 3| 1, winding of relay 316 to ground where a
chain of relays, such as 316, is used to prevent
control circuit may energize the switch combina
tion of primary and secondary switches for con
necting the incoming trunk to the channel se
A group of links and link-control circuits serve
a plurality of groups of trunks which may be
known as subgroups of trunks within the larger
group. When a particular trunk within a sub
group of trunks actuates a link circuit, it is neces
sary to identify the subgroup with which it is as
sociated. The link-control circuit is therefore
provided with a plurality of relays 608 equivalent
to the number of trunk subgroups served through
the contacts of the associated connector relays.
In this instance it may be assumed that a circuit
is established for the group relay 608 to show the
subgroup of trunks requiring service. A circuit
is now established for relay 313 belonging to this
subgroup. There are a plurality of trunks in
each subgroup served by the same start relay
311. These are represented in the control cir
cuit by a plurality of relays, such as relay E00.
the actuation of a connector by more than one
trunk and for the selection of an idle control
It will be remembered that a start ground was
cuit is such that a choice is made from a large
number of channels. In some instances a num
ber of idle channels are simultaneously associ
There are as many trunk relays 600 as there are
placed on conductor 320 of the incoming trunk
circuit. When the control circuits associated 25 when the start circuit was established. This
ground operated relay 311 but at the same time
with such relays are busy no circuit is established
extends ground through a plurality of contacts
for the relay. The energization of relay 316 es
on relay 312 and a plurality of contacts on relay
tablishes an operating circuit for the multicon
313. There are as many contacts on relay 312
tact relay 311 for seizing an idle link-control cir
30 and 313 as there are trunks in a subgroup. This
plurality of contacts is represented by one con
As previously stated the organization of the
tact on relay 312 and contact 5 on relay 363.
link switching arrangement and the control cir
trunks in the subgroup, all of which are initially
operated from the start ground extending
through one of the contacts on relay 312 and
relay 313. The operation of these relays associ
ated with the control circuit and only one of
these is selected. The selection is made by a
ates ground through a chain circuit, such as
chain circuit in a secondary switch level selecting
shown on contact 2 of relay 600, contact 6 of
circuit 604 in which there are a plurality of relays
equivalent to the number of channels which are 40 relay 313, winding of relay 312 to battery. 'I'he
energization of relay 312 releases the start relay
tested. Relay 605 represents one channel. This
311 and opens the leads from all trunks except
relay, however, represents a switch combination
the calling incoming trunk. The start ground
associated with diiTerent channels, such as sec
therefore extends through only one contact of
ondary switch 302 and primary switch 300 or
secondary switch 302 and primary switch 301, 45 relay 313 through the winding of a relay 600
representing the calling incoming trunk. This
relay remains operated and the relays associated
each combination being associated with a difier
ent channel. In the same manner a plurality of
verticals on the primary switch are connected to
verticals on a plurality of secondary link switches.
The verticals of the secondary link switches each
have a plurality of horizontal levels connected to
diiïerent position channels.
The hold magnet
with the other trunks are released. Relay 600
locks over the operating circuit traced to the
start ground. ‘The operation of the relay estab
lishes the level of a primary switch to which the
incoming trunk is connected and immediately
establishes a circuit for the select magnet 304
on the vertical of the primary link switch and
for this level of the primary switch. This circuit
the hold magnet on a. vertical of a secondary link
switch are in multiple so that they may be oper 55 may be traced from battery through contact 1
of relay 600, Contact 2 of relay 31'1, winding of
ated simultaneously. The operation of any of
select magnet 304 to ground. The operation of
the relays 605 indicates that they are associated
select magnet 304 connects ground through its
with an idle channel and the preferred idle chan
contact and through contact 3 of relay 3H,
nel in the chain of relays, such as 605, is taken
for the connection. In practice there are as 60 winding of control circuit relay 601 to battery
energizing the latter relay. The operation of
many contacts on relay 314 of the connector as
channels which are connected to the control cir
relay 600 now establishes a circuit to determine
cuit, Fig. 6. These relays are operated for as
the class of service required by the incoming
sociating the channel equipment with the con
trunk. This class of service is determined by
trol circuit to energize apparatus of the con
the operation of one of a plurality of relays, such
trol circuit for selecting the idle channel and for
asrelay 603, in the control circuit. Since, in
making a test of this idle channel through the
y.this case, only one class is required, a circuit
contacts of relay 315. This latter test is actually
is shown established for relay 003 through the
a secondary or double test to make sure that the
apparatus of the incoming trunk circuit. This
channel is not seized by another control circuit
circuit may be traced from ground through con
immediately after it has been found idle by the
control circuit being described. The operation
of any particular relay, such as 605, determines
the secondary switch level to which the idle chan
nel selected is connected and, consequently, the
tact 4 of relay 500, contact 1 of relay 3H, contact
3 of relay 313, conductor 330, contact 9 of relay
252 of the incoming trunk circuit which is oper
ated thence over lead 331, contact 4 of relay 313,
contact 8 of relay 311, winding of class relay 603
'to battery. The operation of this relay connects
battery through its contact, contact II of relay
3I1, contact 1» of relay 3I3, winding of relay 3I4to ground.
As previously stated there are as
many contacts on relay 3I4 as there are channels
associated with the control circuit. An idle con
trol circuit establishes circuits for one or more
relays, such as 505, in the control circuit. This
circuit may be traced from battery through the
winding of relay 605, contact I3 of relay 3I1,
contact of relay 3i 4, lead 34I, contact 2 of’relay
5 .
.necessary for the release of the control circuit.
>The operation of relay 4II removes ground from
the test lead 34| and this lead now remains
open. This causes the release of relayA 305 in
the control circuit which enters into the release
of the control circuit.
This control circuit Will '
now be released as soon as the trunk start circuit
is opened.
Position channel
The operation of relay 4H establishes obvious
circuits for lighting the busy lamp 401 and the
guard lamp 446. Relay 4I0 establishes an ob
vious circuit for lighting guard lamp 449. The
operation of both relays 4H] and 4H establishes
4II to ground on'contact I of relay 40I. The
establishment of this circuit indicates an idle
channel in a switchboard position attended by
an operator since, as previously described, relayr 15 a circuit for energizing the channel preference
40I is only operated when the operator is attend
relay 402. There are as many relays, such as 402,
ing the switchboard position circuits. The oper
as there are channels in a cordless position.
ation of relay 335 establishes a circuit for operat
These relays, such as 402, 420 and 42|, are in a
ing the double test relay 3I5 as shown from bat
chain circuit to prevent seizure of more than one
tery through contact I of relay 605, contact I4 120 channel at a time or seizure of one channel in
of relay 3H, winding of relay 3I5, to ground.
a position when another channel is connected to
Since relay 305 is individual to the idle channel
the operator’s headset. The operating circuit for
selected, the testing circuit of the control circuit
relay 402 may be traced from battery through
is applied to the apparatus of this channel. This
its winding, contact I of talking relay 4I0, contact
testing circuit comprises delicate apparatus which f 25 3 of relay 4I I, contact 2 of relay 432, contact I
vmay operate if two control circuits are associ
of relay 10I to ground. Other operating circuits
ated with the same channel. This testing cir
for relay 402 are also established through contact
cuit has been limited to relay 6I0 which is now
2 of the monitoring relay 452 when operated or
associated with the idle channel over a circuit
through contact 4 of the backward relay 4I3
from 24-volt battery through its winding, contact if 30 when the latter relay is operated. Relay 402 in
4 of relay 605, contact I5 of relay 3I1, contact
operating establishes a locking circuit for itself
of relay 3 I 5, lead 340 to Llil-volt battery connected
from battery through its winding, contact I of
with contact I of channel relay 4I I. The opera
relay 4 I 0, contact 3 of relay 4I I to ground through
tion of relay 605 also establishes a circuit for the
its contact 2. This relay also opens the operat
select magnet associated with the level of the 135 ing circuit for relay 10| extending through its
secondary switch connected to this idle channel.
contact I and establishes a circuit for relay 4I3.
This circuit may be traced from battery through
The circuit for relay 4I3 may be traced from
contact 3 of relay 605, contact 4 of relay 3I1
‘battery through its winding, contact I of relay
through ground through the select magnet 3I8.
432, contact of the operator’s jack 504, contact
The operation of the select magnet connects;Í
of emergency key 535, contact I of backward
ground through its contact, contact 5 of relay
release relay 500 to ground. The release of relay
SI1, relay 602 to battery. The operation of relay
` 10I opens a circuit for relay ¿lill to cause its re
6I0 indicates that no interference has been en
countered in the selection of the idle channel
and establishes a circuit for relay 600. All of the»` 45
elements to be used have now been tested and
the mechanism associated therewith energized.
The operation of the select magnets of the pri
ymary and secondary switches energizes relays
60I and 602. The test of the channel associated!V
with the secondary switch Was made by the en
ergized relay 606. A circuit may therefore be
established at this time for energizing the hold
magnets of this switch combination for connect
ing the incoming trunk with the selected charl-`
nel. This circuit may be traced from ground
through the contacts of relays B02 and 60|, con
tact of relay 836, contact 2 of relay 505, contact 6
of relay 3I1, contact 2 of relay 3I3, to battery
through the hold magnets 305 and 301.
eration` of the secondary switch 302 establishes
a circuit for channel relay 4H from battery
through its winding, contact 3 of switch 302, con
tact 2 of relay 3I3 thence through contact 6 of
lease so that all channels of the position are
made ‘busy during the period required by the
operator in serving a call entering her position.
This includes supervising operations, such as
talking to either a calling or a called party or
monitoring as explained later. The operation of
relay 4 I3 establishes a circuit for operating relay
402 from ground through contact 4 of relay 4I2,
"contact 6 of relay 4I3, winding of relay 403 to
battery. This alters the guard lamp 403 from a
steady to a flashing condition by the connection
of ground from interrupter 408 through the lamp
filament. This flashing signal indicates to the
position operator that an incoming trunk has
been connected to an idle channel of the posi
tion as a preparatory signal in advance of a tone
signal given to the operator a fraction of second
later. Relay 4I3 establishes a locking circuit for
relay 4I I and a holding ground circuit through
’its contact 3 and contact 4 of relay 4I I for the
hold magnets 305 and 301. The switches 300 and
302 are, therefore, no longer dependent upon the
relay SI1, contact 2 of _relay 605, contacts of: 65 link-control circuit for maintaining their holding
relays 303, 60| and 602 to ground. A circuit
circuit. The operation of relay 403 closes circuit
is also established for relay 4I0 from battery
paths for the talking and signaling conductors
through its winding, contact 2 of relay 403, con
from the trunk through the contacts of the link
tact 1 of switch 302, contact 1 of switch 300,
switches to the cordless position apparatus, opens
lead 32 I, contact 2 of relay I I2, to ground throughY 70 the locking circuit for relay 4I0 which restores to
contact I of relay II3. The operation of relay
normal and closes an operating path for relay
4I I disassociates 48-Volt battery from the testing
404. The circuit for relay 404 is established from
circuit lead 343 and connects ground therewith.
ground on contact 2 of relay 804 in the position
This causes a reversal in the testing circuit of
-control circuit, contact 3 of relay 105, contact I
the control circuit releasing relay 6I0 which is
»of relay 003, contact 1 of relay 500, contact I0
of relay 403, winding of relay 404 to battery.
The latter relay locks to its operating ground.
The operation of relay 403 now energizes relay
used for the via connection. There are also
`trunks which are of these characteristics in so
I I2 in the incoming trunk circuit for opening the
link-start circuit extending to relay E00 of the
link-control circuit. The circuit for relay I|2
may be traced from ground on contact I of relay
which have different signaling devices, such as
the difference in signals between the straight
forward intertoll trunk and the ringdown inter
toll trunk. The class signal in each case indi
cates vthe character of the trunk by associating
far as transmission qualities are-concerned but '
504, Contact I of relay 503, contact .0 of relay
a grounded circuit which may or may not have
403, contact i2 of switches 302 and 300, lead 332,
contact 2 of relay H1, contact 3 and the winding 10 resistance in series therewith and open circuits
in Various combinations with the class relays.
of relay H2 to battery. Relay I|2 establishes a
locking circuit for itself to ground on contact 6
These are connected from the trunk circuit, Fig.
2, through the contacts of relay 20| or a similar
of relay 203 over a circuit including contact 4 of
relay in a diiierent intertoll trunk circuit over
relay I I3, Contact 2 of relay |04, contact 3 of relay
202 and contact 'I of relay I I1. The operation of 15 leads 333 and 334 through the cross-bar switches
relay I I2 removes the start ground from lead 320
of Fig. 3, contacts 1 and 8 of relay 4|3 to the
which extended through its contact I and causes
class relays II2I, ||22, II23 and II24. These
relays are marginal and, consequently, operate
the release of relay 50|! in the link-control circuit.
’I'he release of relay 600 causes the release of
relay 608 which releases relay 3I3. The release
of relay 3I3 opens the locking circuit for relay
3||ì which releases and, in so doing, releases relay
3|1. The release of relays 3I3 and 3|1 opens the
circuit of all relays in link-connector and link
control circuits. The link connector and link .»
control circuits may now serve other calls enter
ing the telephone oñice. As previously stated, a
ground is supplied from the position circuit for
maintaining the hold magnets 305 and 301 oper
according to the resistance in series with the en
ergizing circuit. The following are examples of
Il a ground
ed resistance is connected to lead 333 and lead
334 remains open, relay II2I operates which en
v some combinations that are made.
ergizes relay III1. The latter relay is operated
from battery through its winding, contact of re
lay |I2I to ground on contact II of relay 1|I.
Relay II l1 when operated locks to this operating
ground. When lead 333 is connected directly to
ground with no resistance in series therewith,
ated and, therefore, the switch connection be- i, 30 relays II2I and ||22 are operated which causes
tween the position channel and the trunk remains
the operation of relays I I I1 and III8, both lock
ing to ground `on contact II of relay 1| I. The
same combination is used where lead 334 is either
Class of trunk signals
connected directly to ground or grounded re
The operation of the previously described relay v3.5 sistance which operates relay II23 in one case
1I3 in one of the channels connects ground from
and both relays II23 and |I24 in the other case.
its contact I through the winding of position re
This causes the operation of either relay |I|9 or
lay 102 to battery. The operation of the latter
both relays I I I9 and I |20 which lock in the same
` relay connects ground through its contact 2, con
«ma-nner as described for relays III1 and III8.
tact 5 of relay 500, contact I of the class relays
Varied combinations are used throughout to in
III1 and II I9 to battery through the winding of
dicate the characteristics of the different trunks.
class relay 109. Relay 109 operates and con
These indications are later transmitted to the
nects leads 1I5 and 1| 6 through its contacts I
sender and marker and are used for establishing
and 2 to the windings of class relays II2I, II22,
circuits as will later be described.
I |23 and I |24 to battery through resistances I |25; 45.
and H26, respectively, thus starting class de
Splitting relay
The ground from. contact 2 of re
It will be noted that when any class determi
lay 102 also extends through contact 5 of relay
nation is made the operating path for class re
500, contact 3 of relay 109, winding of relay 1I0
lay 109 is opened by the operation of either re
to battery. Relay 1|0 opens leads 1|8 and 1|9'l 50 lay II|1 or |II9, thus causing the release of re
extending to the operator’s telephone circuit and
lay 109. This relay is slow to release to allow
establishes an operating circuit for relay 1||
time for class determination. The release of re
which may be traced from battery through the
lay 109 operates relay 106 and releases relay 1|0.
Winding of relay 1| I, contact I of relay 1I0, con
The circuit for relay 106 may be traced from
tact 5 of relay 500, contact 2 of relay 102 to; 55 ground through contact 5 of relay 1I I, contact 5
ground. Relay 1II, in operating, establishes a
locking circuit through its contact 6 to the oper
of relay 109, contact 6 of relay 500 to battery
lthrough the Winding of relay 106. During the
ating ground. The class signals are transmitted
foregoing operations a check is made for the
to the position circuit in order that the position
sleeve holding ground provided by the incoming
sender and the marker maybe guided by the 60 trunk circuit when relay 202 was operated as
character of incoming intertoll trunk connected
previously described. If this ground has been
therewith. The incoming trunks which are con
properly associated with the sleeve lead, a circuit
v nected to the cordless position for toll or termi
is established for relay 108 which may be traced
nating connections may be of the ringdown or
from battery through the windings of relays 108
straightforward type from distant toll oñ'ices or A65 and 101 in series, contact 6 of relay 504, contact 6
from tandem offices and they may vary in trans
of relay 5I6, contact 5 of relay 80|, contact 4 of
mission characteristics. For example, a Via in
relay 803, contact 1 of relay 4I3, contact 9 of the
tertoll outgoing trunk must be selected by the
link switches, Fig. 3, thence over lead 329 through
marker for a call from a distant toll office which
contact 9 of relay 20| and contact 4 of relay 202
shall be routed outgoing to another toll oflice. 70 to ground. Relay 108 is locked to ground on
contact 8 of relay 1| I. This holding ground
On the other hand, if a call is for a connection
which may extend from one toll oñice to this toll
later serves to hold the switch hold magnets
operated on a connection which has been estab
oiì‘ice and is terminated in a local subscriber’s
lished when the splitting relay 20| is operated
station, it is not necessary to use a toll trunk of
for talking to the called party. Relay 101 is a
the equivalent transmission characteristics as
lwith responsive to calls of different character.
polarized relay and does not operate unless the
circuit traced is associated with a connection
which has already been established. If this cir
cuit is associated with anestablished connection,
»battery through the switch hold magnets will »
For example, when a call isa new call or con
nection to an outgoing toll trunk, relay II2 is
operated which associated resistance IIO in cir
cuit with relays IOI4, |0I5 and |016. The value
of resistance I|0 is such that only relay |0|4 is
operated. This establishes a circuit for relay
operate relay '|01 to ground on contact 8 of relay
'III or to ground on contact 2 of relay '106.
|003 from battery through- its winding, normal
When »this relay is energized a circuit is estab
contact of relay |0I5, contact of relay IOI4 which
lished for relay 800' through the contact of relay
'101, contact 4 of relay ‘III, contact 2 of relay 110 is operated to ground. This indicates that the
call to be answered by the cordless operator is
'|I0, contact 5 of relay 500 to ground on contact
a new call. In this case the apparatus of the
The operation of relay 800
position toll circuit will establish a circuit for
supplies ground to the position circuit for light
relay IOI'I. In the case of a recall from the
ing lamp |0I0 to show that the position is asso
calling distant operator, the same circuit will be
established with the exception of the circuit for
relay IOI'I. In the case of a recall, relay 800 in
the position apparatus. The operation of relay
the position control circuit is operated and there
'|06 over the circuit previously established asso
will be no circuit for relay |0I'I. Therefore, on
ciated ground with lead 1|'I to operate the split
ting relay 20| of the incoming trunk over a cir 20 a recall a circuit is established to light lamp
|0I0 and a distinctive tone is transmitted to in
cuit which may be traced from ground on con
dicate this type of call. When a manual recall
tact 3 of relay 500 through contact I of relay
is made from a called oñice, circuits are estab
106, lead -II‘I, contact 0 of relay 403, contact 6
lished for relays I I2, 201 and 204 of the incom
of switches 302 and 300, contact 4 of relay ||2,
ing trunk circuit, Figs. 1 and 2. The operation
winding of relay 20| to battery. Relay 20|- in
of the above three relays connects resistances
operating establishes a holding circuit for relay
222 and |I0 in multiple and these multiple re
II3 from battery through its winding, contact 4
sistances are connected in series circuit with re
‘of relay 20|, thence to the operating ground for
ciated with an established connection. Relay
‘|01 is also used in connection with the release of
1' 15
relay 20|. Relay I I3 remains operated after the
lays |0I4, I0|5 and IOI0. The value of resist
release of relay 20| over a circuit traced from
ance 222 in multiple with resistance H0 is such
as to cause the operation of relays IOI4 and I0| 5.
The operation of both relays I0| 4 and IOI5 es
tablishes an obvious circuit for relay |002 which
lights lamp IOI | and associates a distinctive tone
battery through the winding of relay | I3, con
tinuity contact of relay 20|, contact 5 of relay
II3, contact 2 of relay |04, contact 3 of relay 202,
contact 'I of relay II'I, contact 6 ofrelay 203 to
ground. This splitting relay 20| is released when 35 with the operator’s headset. A different signal
is given when the distant called party does not
conversation between the operator and the call
answer. In this case, incoming trunk relays I|2
ing operator has ceased and part of the position
’ Aapparatus is released.
At this time, however, the
splitting relay 20| is operated to disassociate the
'inward and forward ends of the trunk and asso
ciate the forward end with the cordless position
circuit for signaling purposes and for conversa
tion between the operators. The forward relay,
such as 404, of the position channel is operated
and 201 are operated which connects resistances
22| and IIO in series with relays IOI4, I0‘I5 and
IOI6. The Value 4of resistance 22| in multiple
with resistance IIII is such as to cause the oper
ation of all of the aboverelays. The operation
of these three relays establishes an obvious cir
cuit for both relays |002 and |003 which'lights
if no other'forward relay in the sequence circuit 45 lamp IOI2 through their contacts and estab
lishes a circuit for a distinctive tone. v
is operated. A circuit 'for this relay is estab-The tone circuit, known as the order tone, for
lished as described when the backward relays 403
indicating to the operator that a particular con
and 4I3 of the channel operate. Relay 404 es
nection has been established which is either a,
tablishes a circuit for relay 5I5'over an obvious
-circuit and the latter relay establishes a circuit " 50 new call, a recall or that'the connection desired
has not been established. This tone circuit is
established by the operation of relays shown in
the left portion of Fig. l0 over the control relays
service on the same call. The circuit for relay
IOI4, |0I5, I0|6, |002 and |003. The operation
>'|05 may be traced from ground through contact
3 of relay SI5, contact 3 of relay 803, winding of' 55 of either‘relays |002 or |003 indicates to the
position operator that the incoming call is from
relay '|05 to battery.
a ringdown intertoll trunk and also establishes
Position signals
a characteristic circuit to the marker. With
An arrangement of signals is provided which
these relays released circuits are established for
are operated by relay combinations in the posi 60 indicating that the call is from a straightforward
tion circuit under the control ringdown incoming
intertoll trunk. In the case where both relays
intertoll trunk circuits, Figs. l and 2, or incom
are released, three pulses of order tone are trans
ing intertoll trunks of other connections which
mitted toboth the distant operator and the cord
have apparatus responsive to different signals
less operator. When only one of the abovere
transmitted over the toll lines or trunks. The 65 lays is operated, the tone will be transmitted only
operation of apparatus in the incoming trunk
to the cordless operator. One pulse of tone is
transmitted when relay |002 is operated and two
circuit under different conditions connects bat
tery to different values of resistance over lead
pulses of tone are transmitted when relay! 003
is operated.
32| to the position circuit. This lead 32| may
’ be traced to the position circuit through contacts 70
Position tone circuit
-I of the link switches 300 and 302, contact 2 of
The order tone circuit is established from the
relay 403 and thence through the windings of
lfor-relay '|05 which ties the forward and back
-ward portions of the position circuit together for
marginal relaysV |0I4, |055 and IOI6 to ground.
The number of these ‘relays operated depends
upon the value of `resistance associated there
position control circuit which associated ground
with lead |029 through contact 4 of relay |004,
75. lead |030, contact 4 of relay |020, contact'lI of
circuit for relay |004 through contact I of relay
|0|3, contact 2 of `relay |020, contact 2 of relay
|02| to the original ground. Relay |004 in oper
relay |0|8, winding of relay |02| to battery.
Relay |02| is the i'lrst of a series of operations
for energizing and deenergizing the tone circuit.
This tone circuit may be traced from tone source
ating establishes a locking circuit for itself
through its contact 4 to ground over lead |029.
|022 through Various contacts of relays |0|3, .
-The operation of relay |004 separates leads |029
and |030 at its contact 4, thus releasing all of
|0|8, |,0|9, |020 and |02|, thence through the
right winding of tone transformer |005 to ground.
The tone is transmitted by induction through
tone transformer |005, contacts I and 5 of relay
the relays which were held to this ground in
|004 to the talkingconductors which in one case 10
cluding |0|3, |0|8 and |02I.
The foregoing describes the operation of the
tone circuit for transmitting three tones which
extend through contacts | and 4 of relay ||0|
is the maximum used in this circuit arrangement.
and the windings of transformer ||02 by induc
As previously explained, three tones are used
tion to the cordless operator’s headset. As pre
when the toll call is incoming over a straight
viously stated, on certain calls the tone is trans
mitted only to this cordless operator but when a f15 forward trunk and may indicate a new call over
this trunk or a recall by the originating distant
call is transmitted ov`er a straightforward inter
operator. A call from an originating operator
toll trunk, relays |002 and |003 are both re~
leased and the tone is transmitted through con
tacts | and 5 of relay |003, contacts I and 6 of
relay |002, thence to the contacts of relays |00|
and |000, contacts 3 and 4 of relay 403 to the
trunk conductors.
The sequence of operations of the tone relays
is as follows: Relay |02| operates to ground |03l.
As previously traced, the operation of this relay 25
establishes a circuit for relay |02| to the same
ground through contact 4 of relay |02| and con
tact 4 of relay I0|9. The operation of relay |020
closes the tone circuit through its contact 3 from
over an incoming ringdown trunk actuates relay
|003 either when this call is a new call or when
it is a recall from the originating operator. A
recall from the called party operates relay |002
and the called party does not answer both relays
|002 and |003 but relay |002 is the only one
effecting the control of the tone circuit. Under
the condition of a new call or a recall from the
originating operator, using an incoming ring
down intertoll trunk, the operation of relay |003
causes one pulse to be transmitted to the cord
The talking circuit to the in
the tone source |022 and the tone coil |005. Re 30 coming trunk is opened to contacts | and 5 of
relay |003 and thus this one pulse does not reach
lay |020 locks through its contact 4 and contact
the incoming trunk. The operation of relay |003
4 of relay |0|9 which opens the operating cir
establishes a circuit for relay |004 after one
cuit for relay |02| and the latter relay releases.
pulse has been transmitted. This circuit may
A circuit is thus established for relay |0I9
through contact 5 of relay |020 and Contact 3 35 be traced from battery through the winding of
relay» |004, contact 2 of relay |002 which is nor
of relay |02I. The operation of relay |0|9 opens
mal, contact 2 of relay |004, operated, Contact
the tone circuit for ending the first impulse of
| of relay |0I9 which is operated at this time,
tone. The circuit for relay |020 is opened by
and thence to ground over leads |030 and |029
the operation of relay |0|9 causing its release.
A circuit is now established for relay I0 I 8 through 40 through contact 4 of relay |004. Relay |004 in
operating operates leads |030 and |029 and locks
Contact | of relay |0|9 and a locking circuit is
-through its Contact 4 to lead |029. As pre
established through its contact 3. This sequence
viously stated, the operation of relay |004 re
of events again establishes an operating circuit
leases the tone actuating relays and ends the
for relay |02| through contact 6 of relay |0|9
and contact 4 of relay |020. A second impulse 45 transmission of tone after one pulse. The oper
' ation of relay |002 on a recall from a called toll
of tone is started by again closing the tone cir
oñice or information operator’s desk causes the
cuit through contact | of relay |02|, normal,
transmission of two pulses to the cordless oper
contact I of relay |020, contact | of relay IOI8,
ator. These pulses do not reach the incoming
which is operated, and through coil |005 to
ground. The circuit of relay |0|9 was opened 50 and outgoing trunks. The operation of the toll
circuit relays proceed as previously described un
by the operation of relay |02| and releases. A
til relay |020 operates a second time. A circuit
circuit is thus established for relay |020 which
is thus established for relay |004 from battery
is the same as the circuit over which it was
through its windings, inside contact 2 of relay
previously operated. A circuit is also established
for relay |0|3 through contact 2 of relay |0|8, 55 |002, contact 2 of relay |0|8, contact 2 of relay
|020, contact 2 of relay |02I to ground over lead
which is held locked, contact 2 of relay |020 and
|029. Relay |004. opens the tone circuit as pre
contact | of relay |0|9 to the original ground
viously described and locks through its contact
as traced. Relay |0|3 locks to this same ground.
4 to lead |029.
The operation of relay |020 opens the circuit for
The foregoing indicates the action in the cord
relay |02|, causing its release and opening the 60
less toll operator’s position circuit both for a new
tone circuit which ends the second pulse of tone.
call entering this position as previously described,
A circuit is now established for relay |0|9 which
and for a recall from a distant operator. It is
circuit is the same as previously established for
assumed for this description that the distant toll
this relay. This closes the tone circuit for a
third impulse of tone and opens the circuit for 65 operator in toll oi‘ñce |00 requests a connection
to an operator in a distant toll oflice over a via
relay |020. This is the last tone circuit estab
intertoll trunk and, consequently, the apparatus
of the sender 900 and the marker 90| must be
|022 through contact I of relay |02|, contact 2
actuatedin >a manner to actuate the cross-bar
of relay I0|9, contact 3 of relay |0|3, winding
of the tone coil |005 to ground. A relay |02I 70 switches 282 and 285 for connecting the in
coming intertoll trunk, Figs. 1 and 2, with an out
is now energized through contact 6 of relay |0I9,
going trunk 230 extending to ofûce 28|, disclosed
contact 4 of relay |020, over leads |030 and |029
diagrammatically in the right portion of Fig. 2.
to the original ground. The operation of relay
Reference is made to the Patent 2,236,246 to
|02| opens the tone circuit and terminates the
third impulse of tone and also establishes a 75 King, McKim, Myers, March 25, 1941, for a com
lished and may be traced from the tone source
plete description of' thev cordless toll position
equipment, positionr control circuit, position
For this` reason numerous combinations
of call registrations“ are required both for indi
cating the character> of the calling incoming
sender 900 and marker 90| forfoperating the ap
trunkand the character of the outgoing trunk
paratus of. this oliice` to complete thev connection
required for completing the connection. Only
between the. incoming> intertoll trunk: and the in
suñicient apparatus combinations are shown to
formation operator’s trunk. In order> to simplify
carry out the operating circuits of the invention.
this description,y onlyÍ the, partsk which are. in
The- cordless toll operator manipulates the
volved in carrying out the operation of this. in
keys of the position key-set for energizing regis-_
vention are disclosed anddescribed.
10 ters in the sender. These registrations in the
sender are transferred to the marker after the
energization of a marker connector 90| by the
During the foregoing operations which provide
a signal tothe operator indicating'a call> has en
sender which associates the sender with an idle
marker. There are only a small plurality of
tered the position andthe character of the in
coming call, a circuitis established for the sender A15 markers by comparison with the plurality of
senders inthis character of toll oflice and con
start relay 104 as soon. as certain relays are in
sequently a markery connector is used for finding
the following position:y Relay 102 operated, re
an idle marker: and associating the sender which
lay 500 released, relay 1I0" released, relay 1II
has been energized'with this idle marker. Regis
operatedy relay 101 released, relay 105' operated,
and relay 10.3 released; The positioning of the 20 trations are transferred to the marker covering '
the routing of this connection and the character
foregoing relays was-established as'previously de
of" the calling incoming trunk circuit. This in
scribed. The circuit for the4 sender start vrelay
cludes the character of the outgoing intertoll
104 may thereforebe traced‘from ground through
trunk> to be used for the connection. The above
Contact 2l of relay 102', contact 5 ofv relay 500,
contact I of` relay 1I0, contact 4 of. relay V1 I‘I, con 25 registrations in the marker are used for com
pleting the telephone connectionV and for con
tact of relay'10'1, contact 5: of relay 105, contact
trolling >apparatus ofthe cordless toll position as
2 of relay 103, winding of relay 104 tov battery.
soon as this connection has been made. This
Relay-'1041 locks through contact I of" relay SIG,
automatically adjusts the incoming trunk cir
contact 5 of position release relay 804 to ground
through Contact 2 of relay 5I5'which was oper '.30 cuit to either arrange circuits for placingvthe
telephone connection under the constant super- '
ated by relay 404. The operation of the sender
vision of: the cordless toll operator by locking
start relay 104r establishes an operating circuit
the> link switches ofthe channel or for indicating
for senderl control relay 925. in the sender 900
that this supervision isnot-required.
from ground through contact 3y ofr relay 104,
Call registrations Were transferred to the
winding ofi relay 925~to battery.` Relay 9.25 oper
marker from the yclass registers in the lower por
altesÍ relay'103 from> battery through its winding,
tion of position circuit, Fig. 11, for indicating
Contact> 2 of relay SIS, contact ofv relay 925 to
the class of the incoming trunk by operating re
ground. Relay 103 locks to this- same ground
lays 9I'I`, QIZ or 9I3. The operation ofv relay SI2
Vthrough its contact I. The operationv of the lat
ter‘relay opens the operation path for' the sender .40 signals the marl'cerv that. the calling incoming
start relay 104 which now remains operated un
der the control- of its locking circuit which ex
tends through the position release relay 804; ' Re
layy 103fis slow in operation to guard against too
rapid seizure of the sender.
The elements of the position sender may be
roughly divided with respect to theirvfunctions
into principle parts, the key-set, the register cir- y
cuit, the connector control circuit for associating
the connector between the» sender and the marker
and control relays for establishing circuits
through the connector to the marker for oon
trolling the operations of the apparatus in the
marker, all> of which is diagrammatically shown
assender 900.
runk is` a via incoming trunk of the highest
transmission cl’laracteristic.- The operation of re
lay: SI Iy signals the marker that the calling in
coming trunk is a terminal trunk. When relay
- BI I` is energized the telephone connection may
beA extendedv either to a distant toll oñice and
therek terminated» or it may be extended to a
local oiñcezin the areav of this toll oiiice. An in
coming call over a via intertoll trunk may ter
minate in a local' oñice `in the area of' this toll
office. In this case re1ayJ9'I2 will be energized
to indicate` an incomingcall over a via intertoll >
trunk and also relay 9I'3 will be energized by
the coder registers to indicate» the terminating
area of; the call. The energization of route relay
The position sender is now in readiness to re
005, along with other apparatus not shown, is
ceive registrations from the position circuit. The
for a via connection to an intertoll trunk extend
cordless toll operator upon observing a lamp sig- >
ing to another distant toll ofñce. When the in
nal and receiving a tone signal indicating the
coming intertoll trunk is a via intertoll trunk
type call to be- answered challenges the distant 60 and. the outgoing trunk is a via intertoll trunk
operator which in this case is a toll operator at
the connection requires supervision and there
toll cflice IIl0 and receives the code- or code and
fore the route relay energizes a class relay 908
numerical designation of a wanted party.` In
which establishes a combined circuit for auto
certain cases where therx connection to- another
matically locking a link between a position chan
distantv toll oñice is; desired only the code num
nel- and the calling incoming trunk. This cir
ber isgiven to the cordless tolll operator. When
cuit, however, is not completed until the via out
a call incoming from another toll olîice termi
goingk trunk has been selected by the marker
andthe switching paths completed between this
natcs in the area of the toll o?lice receivingthe
idle outgoing trunk and the calling incoming
call, the code designation and numerical desig
nation may be given by the calling toll operator
so that a telephone connection can be completed
The energization of relay SI I- by the class re
in thisarea by the cordless toll operator. A large
lays and the energization of a route relay, such
Variety of combinations ofV interconnections be
as route relay 901, establishes a circuit for re
tween incoming trunks of various, character and
lay âîtß: in;Í the sender control circuit instead of
outgoing trunks of various character are pro-.T LI relay G06.. In this case the route relay ener
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