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Патент USA US2119209

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May 31, 1938.
o. c. HALL ET AL
Filed April 7, 1956
9 Sheets-Sheet l
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. 0. 'c. HALL
May 31, 1938.
o. c. HALL ET AL
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Filed April 7, 1956
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May 31, 1938.
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Filed April 7, 1936
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May 31, 1938.
o. c. HALL ET AL
Filed April 7, 1936
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May 31, 1938.
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Filed April 7, 1936
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May 31, 1938.
o. c. HALL ET AL
Filed April 7, 1936
‘ 9 Sheets-Sheet 9
0. C. HALL
Patented May 31, 1938
1 a loliverIOulHallyFair Lawn,.N. .J., and .JohnQF.
.Toomey,‘Newy.York, N. Y., .assignors to,,B'ell
Incorporated, New
‘ 1' Telephone 1‘; Laboratories,
Y , ‘York, _N. jY., a corporation ofiNew‘wYork
" ‘Application “April '7, 1936, Serial ‘No. 73,110"
120201311115. (‘CL 179-—43)
This invention‘ relates to telephone systems. and double-ended‘cord circuit, being ‘used‘for out-v’
more particularly to systems; for. switching toll ‘ward calls, i. e. calls originating locally for ex
or long distance lines of different characters.
tension over toll lines to a distant point.
In a‘ copending application, Serial‘No. 108,146,
‘ This" system is'verye?icient and satisfactory
“?ledon Oct. 29, 1936, ‘by‘Meszar and 'Wiese, ‘an forillarge o?iceslbut may be undesirable, from;
arrangement is disclosed whereby'when an‘ in i a cost standpoint,‘ for‘smallo?iceswhere a small Si)
coming automatic ‘or voice-frequency straight
number of operators,‘ operating as a single group,
forward toll line is connected‘in, tandem to a could handle all of the toll traffic both inward,
second line of the same type, or to‘ a completing ‘ through‘ andoutward were they'in a position to
trunk circuit, the supervisorysignals originating
at the terminal o?lce or subscriber's station are
An object of. the present invention, therefore, is
transmitted back through the switchingpoint to “to provide‘ such an arrangement that a single
the outward toll operator.
operator can handle all types of toll calls.
In the Meszar et a1. arrangement mentioned the
A feature of the ‘invention whereby the fore
-, straightforward lines terminate in a single cord going object is obtained resides 1113511011‘ an ar-;~
and plug at the‘ inward or through position.
‘ rangement of toll lines; trunk circuits and cord
When the outward toll operator connects a call
circuits, that all such- types'of lines, i. ‘e., both
ing line to the outgoing straightforward line the I inward and outward trunks, straightforward toll
distant inward and through operator is‘automati
lines andring-down toll'lines maybe terminated
E20 cally connected, receives the. order and inserts at a-single' operator’s position and interchange
‘the plug terminal of‘the line either in a trunk ably connected ‘at will by‘ means ofa universal 20
‘ jack, in the case of a terminating connection or double-ended toll cord circuit varranged to adapt
into the outgoing jack of another toll line. In itself for the proper kind of supervision, i. e.,
‘ the ‘case of a terminating connection‘ supervision through or terminating depending upon the types
.25 received from the terminating local o?ice ‘or called of lines connected thereby.
subscriber’s'station will be transmitted through
"Another’feature resides in a novel method of;
the toll operator’s ‘position back over the incom ‘ controlling the exclusion of transmission loss pads
ing line to the outward or originating toll. oper * from tolllines-whentwo lines, so equipped, are
ator’s position without displaying any signals at connectedtogether by- means of a vcord circuit
the inward and through position. In‘ case the call
is to be routed to a distant city “the inward and
through operator plugs the calling‘line into a
second straightforward line outgoing to. the .de—
sired point.
In this case, also, any supervisory
‘signals originating at the distant end of ‘ the con
nection are transmitted back over both‘straight
which- method COIlSlStSril'l so connecting the pad.
control'relay of each line to the‘ line conductors“
in series with a battery, and so arranginglthe cord
circuit thatpwhen' the. lines'are connected to
gether, and .the cord circuit talking key is not
. operated, the talking conductors of the cord cir-,
cuit are reversed »with respect. to the two ends‘
forward lines to the outward operator without thereof, thereby connecting the tip of one line
displaying any supervisory signals at the inward
to the ring of the other line‘and vice versa where
and through positions.
At the inward and through position outgoing by the pad control relay of each'line will receive
ring-down toll lines are also terminated ' over ‘operating'current toexclude the respective pads 40
from the lines.
which the operator may extend a calling straight
‘ forward line.
In this case a reverting ring from
the distant end of the line such as a “ring-off”
Another feature resides‘ in ‘so arranging the
cord circuit that when the operator plugs into a
calling straightforward ‘toll‘line and actuates the
passes through the intermediate operator's posi
tion and ‘signals the outward operator without . talking key, a “zip” order tone will be connected 4
to‘the, calling line ‘as an~indication to;the outward
affecting the supervisory signals at the intermedi
ate through o?lce.
operator that ‘the-inwardand'through toll oper
In‘ the Meszar et al. arrangement, due to the
fact that the inward ends of the straightforward
lines are plug~ended, separate inward and.
ator is connectedand that she ‘may pass the order.
In the patent to L.‘_F. Porter_~1,608,524, issued
November 13, 1926 atoll system comprising a toll
through and outward switchboards are-required, ‘ cord Fig. 2 and a ring-down toll line Fig. 3 is dis
closed-whereby ringing current is .connected to
clusively for terminating through calls and the the toll line by means (relayr301) controlled by
1 outward board,- which is‘equipped with-the usual direct current connectedto the tip of the cord‘
‘ the inward. and through board. being used ex
2. .
'by operation of the ringing key. This general
arrangement is standard practice at the present
time, but has the disadvantage that the tip con
ductor of the line is permanently grounded
through a retard coil and the ringing control
means. As the ring conductor of the line is also
used in a similar manner to perform other func—
tions such as “transfer”, which necessitates a
similar permanent ground thereon through the
10 lower winding of the retard coil andleft-hand
winding of relays M5 and 3M, it will be noted
that an impedance bridge exists across the line
which may be traced from the tip through the
upper winding of the retard coil, winding of relay
15 301 and resistance 308 to ground and from ground
through relays 314 and 3l5 and lower winding
of the retard coil to the ring of the line.
Another feature of the present invention, there
fore, resides in a novel means for controlling the
20 various desired signaling functions, over the tip
and ring as heretofore, which obviates the neces
sity of a permanent ground connection to the line
Ringing is accomplished in this case by a mar
25 ginal relay arrangement controlled over the sleeve
of the cord and line, whereby, when the ringing
key is operated the ringing relay is connected to
the tip of the line only while the key is operated.
Operation of the ringing key also connects ground
30 to the tip of the line causing the ringing relay to
operate. Other functions previously controlled
over the ring are likewise controlled over the
sleeve by the operation of keys in the operator’s
position which connects the proper relay to the
35 ring conductor which operates to ground simul
taneously applied to the ring conductor by the
actuation of the same key.
Another feature of the invention is a single
lamp per line which serves both as an idle line
4:0 indicating signal and also as a line or calling sig
nal. When the line is idle the lamp burns stead
ily at reduced brilliancy. When a call is received
the brilliancy increases and the lamp starts to
The invention will be more fully understood
from the following description in which; Fig. 1
represents the line end of an automatic toll line
together with Fig. 1A representing a‘ pad circuit
for transmission purposes; Fig. 2 represents the
50 toll of?ce end of the automatic toll line; Fig. 6
represents the toll office end of another automatic
toll line identical with Fig. 2 for the purpose of
more readily tracing a call from one line to an
other of said lines, Fig. 7 represents a two-way
55 ring-down toll line; Fig. 8 represents a two-way
trunk circuit for use in recording and completing
calls~originating from subscribers in manual of
?ces and for completing connections to subscrib
ers on connections terminating at the toll office;
60 Fig. 9 represents an out-dialing trunk circuit for
completing calls on a dial basis to subscribers on
' connections terminating at the toll of?ce. A de
scription of the initiation and completion of calls
over these circuits in conjunction with a toll op
65 erator’s cord circuit of Fig. 3, the operator’s posi
tion circuit of Fig. 3A, a position dial circuit of
Fig. 4, an operator’s telephone circuit of Fig. 5
and order tone circuit of Fig. 5A will serve to
illustrate the various features of this invention
70 wherein Fig. 10 represents the arrangement of
Figs. 1 to 9 of the drawings. For convenience the
reference characters used have been chosen in
groups of I00, those from I00 to I99 referring to
Fig. 1, 200 to 299 to Fig. 2, etc.
General description of operation
Inge'neral the operation of the present system
maybe brie?y outlined as follows: Both the auto
matic toll line and the ring-down toll line in this Cl
system are arranged to function on calls in either
direction. When therefore the front plug of the
toll cord of Fig. 3 at an outward position is
plugged into the outgoing jack 661 of the toll
line of Fig. 6 extending to a distant o?ice, the 10
relays of these circuits function; to extinguish
the associated idle line indicating lamp (H9
thereby enabling the next idle line indicating
lamp to light; to light the associated cord super
visory lamp 344; and to send out a voice-fre 15
quency signal over the talking conductors to the
distant oflice. This signal is received at the dis
tant office by a circuit organization such as shown
in Figs. 1 and 2 and which functions; to return
an acknowledgment signal to the originating of 20
?ce after the calling condition is registered, in
order that the connect signal may then be cut off;
to start the associated trunk lamp Hi to ?ashing
for indicating an incoming call to the inward toll
operator. The ?rst inward operator answers by 25
inserting the rear plug of her toll cord into the
associated jack 248 and at the same time operat
ing her talking key on the toll cord which results
in; extinguishing the ?ashing line lamp 22 I ; auto
matically causing the toll cord of Fig. 3 to be 30
associated with the common toll signal equip
ment shown in Figs. 3A, 4, 5 and 5A; and auto
matically sending zip tone back over the talking
conductors to the calling operator as an indi
cation that the second operator is ready to re
ceive the number of the called subscriber.
When the calling toll operator passes the want
ed subscriber number the incoming operator then
plugs the front end of the toll cord into jack 661,
if the call is required to be completed over an 40
other automatic toll line or jack 100, if the call
is to be completed over a ring-down toll line, jack
800 if she completes the call over a toll switching
trunk, or jack 900 if the call is to be completed
to a dialed subscriber in the local o?ice. In the
case of the call being extended over another auto
matic toll line the same action takes place as
when the ?rst operator originated the call on the
previous toll line, namely, extinguish the idle line
indicating lamp, light the associated cord lamp
and send on a connect signal to the next toll 50
of?ce. The next inward operator answers the
incoming ?ashing signal, and the same action
takes place as described for the previous operator
except that now the original operator hears the
zip tone from the last operator’s telephone and
order tone circuit. The ?rst operator again
passes the wanted subscriber number and the
connection is then assumed to be completed over
a standard toll switching trunk to the wanted 60
When the called subscriber answers, the toll
line circuit then automatically sends back a re
ceiver-off-hook signal which passes through the
toll cord at the intermediate toll of?ce, and is 65
received by the originating toll line which returns
an acknowledgment signal to the line and causes
the ?rst operator’s toll cord lamp 344 to be ex
tinguished. If the called subscriber hangs up for
any reason, a receiver-on-hook signal is similarly 70
transmitted to the originating toll line circuit
where it is acknowledged and cord lamp 344 again
lighted. If the called subscriber flashes-in the
calling operator then the above noted signals are
transmitted over the toll line alternately and the 75
cord lamp 344 thereby follows’the called sub‘ ‘ there is interposed in line L a ‘directional ‘selection
s‘criber switchhook. When however the called
subscriber‘ hangs up at the end of conversation
the lamp 344 burns steadily and the originating
operator takes down the cord plug which causes‘
the toll line‘to- send a disconnect ‘signal which
the toll line at the through 'of?ce acknowledges
‘by giving the through operator a steady ‘cord
lamp 304 and sending back an acknowledgment
‘10. signal to the originating toll line which in turn
terminates the disconnect signal and the circuits
I restore to normal. The through operator in turn
‘ disconnects her plug in a similar manner which
causes the toll line to send a disconnect signal
15 to the terminating operator.
The toll operator‘
at the terminating of?ce therefore receives a dis
connect signal by noting a steady light 304 and
she also then disconnects her toll cord and an
acknowledgment signal is returned to the inter-'
mediate toll line causing the disconnect signal to
cease and the apparatus all to restore to normal.
Assuming now, in the call described above, that
the number had been such as to require comple
tion at the intermediate toll oilice over the ring
down toll line of Fig. 7 instead of over a second
automatic toll line. In this case the intermediate
toll operator inserts the front toll cord plug into
jack 100 instead of jack I561.
Connection between two automatic toll lines
For the purpose of describing the through
supervisory features,
ringing, transfer,
other signaling and control functions on toll lines
of this character a call will be traced; as it orig
inates in one toll of?ce, referred to as office X;
as it is carried through an intermediate toll office.
referred to as o?ice Y; and as it terminates in a
third of?ce, referred to as o?ice Z. Since the de
tailed description of the automatic toll line repre~
~40 sented by Fig. 2 on such a call depends on
whether the call is being described in an inward
or an outward direction, Fig. 2 will be referred to
when the call is inward and Fig. 6 will be referred
circuit composed vof coils I I 03,1I04, I36, andf‘con
denser “I31 whichiis of the nature of a hybrid
I transformer.
Such ‘an arrangement is disclosed
and claimed’ in the patent to George Crisson‘ No.2 5
1,755,243 issued April 22, 1930 and as it forms‘ no
part‘ of the ‘present invention, it is deemed suffi
cient to merely state‘that it prevents'the voice
‘frequency signal applied to the line L by relay
‘I20 from becoming effective over 1eads'I38 and’1 10
‘I39 in operating the signal receiving apparatus
of Fig. 1B Without interfering with incoming high
frequency signals whichmust be registered by the
apparatus of Fig. 1B. To facilitate this selection,
whenever an outgoing signal of 1400 cycle carrierl 05
‘frequency is‘ being sent, relay I44 remains in its
normal position, thus tuning the incoming leads
‘I33 and I39 to receive signals having a frequency
of 1000 cycles. When signals of 1000 cycles are
being sent relay’ I 44 is in an operated position-‘520
which by connecting coil‘I45 and opening the
condenser I40 tunes the incoming circuit to re
ceive signals having a 1400 cycle carrier fre
High frequencies of any suitable values mayiil25
be used in signaling of this character. For the
system here described high frequencies of 1000
cycles and 1400 cycles are employed as the car
rier frequency. Three separate signals are then
obtained when 20 cycle, 30 cycle or 45 cycle cur-"130
rent is superimposed on the carrier frequency
of 1000 cycles. The acknowledgment signal has
20‘ cycle current superimposed on a 1400 cycle
carrier frequency. The receiving apparatus
shown in Fig. 1B for identifying the incoming‘? 35
signal includes transformers I05, I06, and I01;
an ampli?er vacuum tube I08 and a recti?er tube
I00 for separating the low’ frequency current
from the carrier frequency; and a vibrating‘ polar
relay IIO for responding to the low frequencyilil?
component. ‘The output of this network con
nects over leads III and H2 with three low fre
quency tuned circuits‘ designated A, B and C.
‘to when the call is outward in direction. Thus
45 on calls originating at of?ce X a toll cord the
Tuned circuit A responds to 20 cycle frequencies
same as in Fig. 3 is assumed as being plugged
into a toll line the same as Fig. 6. The line end
serieswith a condenser IIII, recti?ers H5 and
and consists of a tuned coil II3 connected inski?
direct current relay H6. Similarly, tuned circuit
Fig. 1 of the toll line then is assumed to connect _ B
responds. to 30 cycle frequencies for operating
with a similar Fig. 1 at oflice Y and which in turn
connects with Fig. 2. The toll cord of Fig. 3 in relay II ‘I and tuned circuit C responds to fre
this o?ice then serves to illustrate its use on
through supervision. In extending the call out
ward to office Z the operator in office Y thus is
I assumed to plug into the toll line of Fig. 6 and
I again the line end Fig. 1 of the extended toll line
is assumed to connect with a similar line end at
office Z and which in turn connects to Fig. 2.
Before proceeding to trace the call outlined
above it should be observed that the transmission
60 and reception of high frequency signals over tele
. phone lines for supervisory purposes is not new.
To facilitate this description however reference
may be had to Patent No. 1,860,446 to R. S. Bailey
et al. which describes in detail that part of the toll
, ‘line shown in Figs. 1 and 1B.
Brie?y‘ this ar~
rangement involves transmitting an acknowledg
ment signal of predetermined frequency back
. over the line whenever ‘an incoming signal ar
‘ rives. The receipt of the acknowledgment signal
70 at the sending end resultsin cutting off the sig
‘ nal being sent. When the incoming signal ceases
‘at the receiving end of the line it causes the ac
knowledgment signal ‘to cease. Since this neces
sitatesa circuit arrangement that both sends and
receives high‘ frequency ‘signals simultaneously
quencies of 45 cycles for operating relay‘ “8.050
Incoming signals therefore operate relay I I6, I I‘!
or II8. If relay II6 operates it connects ground
to winding of relay I I9 thence to battery at break
contact relay I20 thereby operating relay I I9 and
connecting 48 volt battery I2I through high re-c55
sistance I22 to lead I23. If relay II'I operates
it connects ground to winding of relay I24, thence
to battery at break contact I20 thereby oper
ating relay I24 to connect ground through resist
ance I25 to lead I23. If on the other hand relayiJ-BO
II8 operates, it connects ground through the
back contact of relays I24 and H9 direct to lead
I23. The three different kinds of incoming sig
nals therefore are transformed into three ,corre
sponding conditions that are connected to leadt65
I23 as above described and these conditions will
be referred to in the description that follows
without repetition of the above explanation.
While the function of. the apparatus shown in
Fig. 1B is to receive and transform incomingwo
signals from the toll line to battery or ground
signals on lead I23 to Fig. 2, the function of re
lays I26 to I32 inclusive of Fig. 1 is to convert
battery or ground signals on lead I33 coming
from Fig. 2 to‘ high frequency carrier‘signalss75
“ 2,119,209
for transmission over the‘ toll line. Lead I33 is
connected in series through relays I26, I21 and
I28 to negative 24 volt battery. Relay I26 be
ing polarized responds by operating when nega
tive 48 volt battery through either a high or low
resistance is connected to lead I33 but does not
operate on ground signals. Relay I21 is both
sensitive and marginal and operates whenever
direct ground, ground through a low resistance,
10 or 48 volt battery through low resistance is con
nected to lead I33. It does not operate however
when 48 volt battery is connected through a high
resistance to lead I33. Relay I28 is marginal but
not very sensitive and only operates when direct
“ 15 ground is connected to lead I33.
Fig. 1A represents a transmission pad circuit
of the usual type controllable over lead I34 from
Fig. 2 for reducing the transmission equivalent
of the toll line at originating and terminating
toll o?ices but removed from the line on through
connections at intermediate offices. Lead I34 in
this invention in addition to controlling the
transmission pad also affects incoming signals to
lead I23 depending on the type of circuit to
125 which the automatic toll line is connected. This
is accomplished by the addition of relay I20 con
nected from 24 volt battery in series with the
pad control relay I35 to lead I34. Relay I20 be
ing marginal operates for example when direct
30 ground is connected to- lead I34 by the toll line
of Fig. 2 as will later be described, thus indicat
ing that said toll line is connected to another
automatic toll line. If, however, said toll line is
connected to a ring-down toll line arranged for
I' 35
transmission pad control, then the ground to
lead I34 is through a resistance which permits
pad control relay I35 to‘ operate but does not al
low marginal relay I20 to operate.
In the lat
ter case the incoming signals are not altered.
40 In the former case, however, when relay I20
operates it removes battery from the windings
of relays H9 and I24 thus permitting only a dis
connect signal to be received as will later be de
scribed. When the automatic toll line is connect
45 ed to a ring-down toll line not arranged for
transmission pad control, no ground will be con
nected to lead I34 thus preventing either of re
lays I20 or I35 from operating and in this way
the transmission pad remains in the circuit and
the incoming signals function the associated
two-way automatic toll line relays of Fig. 2.
Whenever the connection is interrupted, as will
later be described, by the operation of a talking
or splitting key in the toll cord of Fig. 3 or by
the removal of a plug from the jack, ground will
be removed from the lead I34 causing relay I35
to release also relay I20 if same had been operated.
Assuming now that the toll operator at the
originating o?ice X inserts the front cord plug
in jack 661, a path is closed for lighting the
cord lamp over a circuit traced from battery
through cord lamp‘ 344, contact 345, relay 300
which is assumed to be normal at this time, lead
343, ,contact 346 on key 341, sleeve lead 348,
thence through plug and jack to sleeve lead 635
and 636, thence to ground both through right
winding relays 631 and 038 in series, and to
ground through the left windings of said relays
and right front contact relay 655. The cord
lamp 344 now remains lighted until the called
subscriber in the distant office answers as will
presently be described. The circuit thus traced
causes relays 631 and 638 to operate and the lat
ter relay in turn connects ground over lead 639
75 for operating relay 640 to battery. Relay 640
then closes a path for operating relay B50 traced
from ground at left back contact relay 006, con
tact 601 on relay 640 to battery through winding
relay 050. Relay 640 at its left inner contact
closes a path for operating relay 655 traced from
ground at left back contact relay 600, contact
652 on relay 540, to battery through winding re
lay 055. Relay 640 also operates relays 508 and
601 from battery at its left outer armature and
contact to ground through lower winding relay 10
600 and winding of relay 601 in multiple. The
operation of relay 601 thus opens the winding of
relay 5I4 causing its contact to open thereby ex
tingm'shing idle indicating trunk lamps 6I9 and
62L The operation of relay 650 closes a path for
causing 2. connect signal to be sent to the distant
toll o?ice Y which may be traced from ground
through resistance 649, left back contact and
armature relay 605, front contact and armature
relay 650, contact 65I on relay 0I3, contact 621 20
on relay 028, right back contact and armature
relay 629, thence over lead I33 and through wind—
ings in series of relays I26, I21 and I28 in Fig.
1 to negative 24 volt battery. Relay I21 operates
and closes a path for operating relay I3I over
a path traced from ground at right contact re~
lay I26, bottom armature and back contact I20,
lower front contact relay I21 to battery through
winding relay I31. Relay I3I operating at its
bottom inner contact connects ground to wind
ing of relay I44 thus tuning the receiving circuit
of Fig. 1B for an acknowledgment signal having
a carrier frequency of 1400 cycles. Relay I3I at
its top inner contacts also operates relay I20
for sending out a connect signal of 1000 cycles— 35
20 cycles which is connected to the front con
tact of relay I29 by relay IN.
The connect signal is registered by the auto
matic toll line at of?ce Y which then returns an
acknowledgment signal to o?ice X as will pres 40
ently be described. The receipt of an acknowl
edgment signal at the originating of?ce X causes
negative 48 volt battery I2I through a high re
sistance I22 to be connected to lead I23 as pre—
viously described. This causes relay 600 to op 45
erate and connect ground through contact 604
on relay 005 to winding relay 606 to battery. The
latter relay in operating at its left armature and
break contacts opens the ground path previously
traced for operating relays 050 and 655. Relay
050 releases thereby opening the circuit to lead
I33 and terminating the connect signal being
sent to distant office Y. Termination of the con
nect signal at office Y in turn terminates the ac
knowledgment signal which will presently be de
scribed, thus releasing relay ‘500 which in turn
removes ground for holding relay 606. The lat
ter relay continues, however, to be held by ground
traced at right back contact relay 632, leads 63I
and 030, contact 609 on relay 606, thence through
winding relays 605 and 606 in series to battery.
Relay 005 operates in this circuit and thus pre
pares the circuit for further signaling which will
later be described.
When the connect signal, on the call here be
ing traced, comes in at office Y it may come in on
toll line which is not the ?rst idle line or it
may come in on a line which is the ?rst idle line.
For the purpose of this description the latter
case is assumed and relay 2“! is accordingly
shown in an operated position. Loops 2I9 and
223 at this time are burning dimly on low alter
nating current voltage extending from ground on
transformer 2I6 over common lead 2I1, through
front contact and armature; directly to lead H8
‘ for “ lighting - lamps '2 l 9‘ at outward/‘toll positions;
signal to ‘the toll line circuit at-the distant of?ce
which cuts 01f the connect. signal being sent,
thereby causing relay 200 to release. The re
and through left break» contact andrarmature re
lay 2J2 to lead 220‘for lighting lamps-2M at the
inward toll position.
moval of ground from conductor 203 which is
The connect signal, upon ?rst being received
at o?icelY results in connecting 48 .volt battery
holding relay 206 operated thus permits relay 205
l2] through‘ resistance‘ I722 to lead- l23‘lwhich'
may further be traced throughwinding of po-»
larizedwrelay 200 in series with slow operate re
lay 20| and marginal relay 202to 24-volt battery.
Relay 7:30 i ‘ i being. marginal does- not ’ operate- be
cause‘ of the high resistance I22.
lay 200 ‘is poled so thatlit operates‘at‘thistime
thereby connecting ground'to lead- 203 which is
15 traced further through contact 204- on relay 205,
then throughwinding relay 206 to‘ battery. The
operation of relay 206 at its left outer make
contactconnects battery to the winding of relay
201 and to the bottom winding relay 20B causing
20 both relaysto operate.‘ Relay 206-at. contact
203 prepares a path ~for. operating relay 205~when
battery isremoved fromrlead 123. Relay 205<at
contact 2H) connects ground to the armature of
relay. 2! I, whichpath‘traced throughgthe back
25 ‘contact of‘ relay 2| lisusedto energize winding
relay 2 l2 andrightwinding relay 2l3 in ‘multiple
Going back to ‘the operation-of relay‘20‘l it‘will
be observed thatthis relay functions as a'busy
30 relay because‘ at its-break contact it opens the‘,
circuit of relay- 2l4wand: that.its make contact
extends battery 2I5 :throug-h-to the‘ armature of
relayI 2M- of .the- next‘ automatic toll (line: Bat
tery 2l5> therefore operates relay .214- of-ther?rst
35, toll linethat is .idle, that is,- whose‘relay 201»is
Thev operation. of - relay“ 20‘! causes» re
to operate on its right-hand winding and at the
same time continue to hold relay 206 operated.
This path is traced from battery through wind-
ing‘relay 206,- right winding relay 205,.contact
209 on relay 206, conductors 230 and 23! to 10
ground at left inner break contact relay 232.
The operation of relay 205 at its left outer break
contact then opens the 48 volt negative battery
path previously traced to lead I 33, thus cutting
off the acknowledgment signal to the-distant 15
The inward toll operator at o?ice Y‘ noting
the ?ashing of toll line lamp 22I picks up the
rear plug of a toll cordcircuit such as shown in
Fig. 3 and inserts it in jack 248 of the calling 20
toll line of Fig. 2. This action causes a-zip order
tone to be transmitted‘to the calling toll opera
tor at distant of?ce X which is an indication
to her that the toll operator at oflice Y is ready
to receive the wanted subscriber's number: The
insertion of the rear plug in jack 248 connects 25 ‘
cord conductors 30l and 302 with toll line con
ductors 233' and 234~respectively. Also in like
manner- toll sleeve conductor 303‘ is connected
with line sleeve 235. If it be assumed that the 30*
toll operator has not as yet thrown talking key"
300,‘ then the sleeve condition may. be‘traced
from battery through cord lamp 304; contact
305 on relay 306-, lead 301, lower contact on
ringing key 308, thence‘ over sleeve 303 of plug 35.
a'ndsleeve 235‘ of tollline jack, through right- ‘
hand armature and back contact relay‘ 229, lead
236 and left-hand windings of relays 231 and‘
operated,‘ a- high voltage- 60 cycle currentthrough ’ 238 in series to ground. S1eeve‘relays-231
40 a ?ashing interrupter 222iisr connected; through‘ 238 operate but the resistance of these left-hand
the leftfront contact relay-2l2rtoilamps 22I-in windings is too high to permit cord-lamp 304 to
front of inward operator positions; Lamps 219 in ’ light. Relay 238 closes ground to lead 239 for
lay 2|4to release and-.openthe low voltage cur
rent: path. Atthe same" time relay 2I2. having
front . of . the outward , positions however,- remain
out due. to the left break-contacton-“relay 2l2=‘ If
45 instead .ofassuming an‘ incoming call on this toll
line. we were to have-assumed it to" be’ taken for.
use by-a tolloperator then relay 201-."would-have
operated as before. but 212 would remain: normal.‘
Inthis case. all lampsm2l9wand22l ‘would be ex~
50 tinguished. Again“ if this toll line had-beenias-v
sumed to be some intermediate idle toll-line the
lamps 2.l9..and 22!. would - also- be out: It. will
therefore be. apparentthat the. use of .a single
lamp. .perline appea-ranceserves as‘ an ‘idle indi
55 cating‘ lamp. for. outward » calls andalso as a
?ashingline. lamp. on incomingvcalls.
The incoming orrconnect signal in addition to
lighting lamp. 22L causes an-acknowledgment
signal to. be. sent- backtoithe- callingatoll line:
This isv accomplished .by. theaoperation'of relay
2l3lpreviously' mentioned. Contact'223 on said
relay closes.ll8._volt~.negative. batterythrough a.
high. resistance»l33,.which path is
further traced through'the right .front- contact
. of the operated .relay.2l2, leftback contact and
armature relay 205, and arma
ture relay. 225,. leftback contact‘ and armature
relay 226, contact 223. on .relay '-2l3,- normal con
tact 22.1. on relay 228, thence through left back
,contactand armature relay- 229. to lead I33.-v
As . previously described polarized relay‘ "I26"
operates‘ under this. condition and in turn oper
ates relay I29 tosenda 20.,cycle signal superim
posedaon 1400.cyc1e- carrier frequency. - This
constitutes an. answer. backor acknowledgment .
operating relay 240 to battery. ‘Relay 240~at its‘
left outer contactv connects ground to winding‘
relay 2“, causing it to operate, which‘in turn 45:
releases relay 2l2 to extinguish-‘line lamp 22I.~
Relay 2l3 .which'previously. operated ‘in multi
ple with relay 2l2 does not release due‘ to battery
througlrmiddle locking winding, contact 24! to
ground .at left inner armature relay‘ 232. There 50c
fore, contact 242.‘ on ‘relay 2l3 connects positive
24>voltbattery 243‘ through relay 244 to break
contact 245 .i on relay 246 and-thence through
lower winding of impedance coil 24'! and lower
contactrelay208 to ringv conductor 234. When 55.?
the toll operator throws her talking key 300 posi
tive battery 243 connected to ring conductor 234
may further be traced over the ring 302 of
the toll cordin Fig. 3, contact 309 onringing
key- 308, conductor 302A, contact 3| 0 on oper 601"
atedrelay 3H, thence over lead 312“ and bottom
break-contact on relay 3l3, lead 314, bottom
break contact relay 500,. through winding 50! on
repeating. coil 502. over lead» 503 and through
windingpolarized relay 504 to ground. Relay 65
504' operates. and connects groundto winding
505, thus closing a circuit ‘for zip order tone potential through. winding- 505 traced over leads
506, .501 and 508. Thistone induced in wind
ings SM and 509 is then i-heardlby the calling
toll operator because talking‘lconductor 302A of ‘
the toll cord is connected to the winding~50lby -
leads 3|2 and. 3M’and because talking conduc
tor 30| connected through contact 315 on.
operated relayjllltolead.316, thence through
75 c
contact 3" on operated relay 3I8, lead3I9 and
top break contact on relay 3I3, to lead 320,
thence through top break contact relay 500, to
winding 569. Talking conductor 30I is traced
through plug and jack over conductor 233,
through pad circuit windings I40, conductor I42
and top break contact relay ‘I29, directional se
lection coil I03, and conductor IOI to distant
end of the toll line circuit similar to Fig. 1. Talk
ing conductor 302 is similarly traced through
plug and jack over conductor 234, through pad
circuit windings I4_I, conductor I43 and bottom’
break contact I29, directional selection coil I04
and conductor 102 to distant end of the toll line.
A further description is here given of other
actions that follow the throwing of talking 'key
360 mentioned in the previous paragraph. In
the ?rst place contact 3V2I on key 300 closes a
5I6, 5|‘! and 5I8 in turn. In this manner a zip
tone of three zips is transmitted to the calling toll
operator. Relay 500 in operating also short cir
cuits condensers 520 and 52I leaving the toll op
erator’s induction coil 522 connected to leads 3M
and 320 ready for receiving the wanted subscrib
er’s number which is now passed by the distant
calling toll operator.
Another action that follows throwing of talk
key 300 has to do with insuring the connection 10
of only one toll cord at a time to the position cir
cuit of Fig. 3A. Inasmuch as this feature does
not come within the scope of this invention no
description will here be given. Description of
this and other features of the toll cord of Fig. 3
may be found in Patent No. 1,608,524 to L. F.
Let it now be assumed that the called sub
circuit for operating relay 306 traced from
20 ground at contact 322 on relay 323. Relay 306
at its inner left make contact, closes ground for
scriber number requires that the incoming op
erator at o?ice Y complete the connection over
another automatic toll line such as the one shown
in Fig. 6. Let it further be assumed that the toll
line shown in Fig. 6 is the ?rst idle line connected
the distant toll office through which the call
304 to lead 325, which is further’ traced through
must be connected. In this case relay 601 will be 25
25 relays 326 and 32‘I_ in series to battery on lead , normal and all preceding line circuits will be
328. The direct battery supply to lead 328 is
further traced through contact 400 on transfer busy so that battery 6I5 may be traced through
armature and back contact relay 601 thence
key 40I, contact 402 on key 405, lead 403, thence through
winding relay 6I4 to ground. Lamps
through contact 329 on relay 3 I3, lead 330 to lead
operating relay 3II direct to battery; at contact
324 it transfers the sleeve lead 301 from lamp
' BI!) and 62I are therefore burning dimly on in 30
30 328. 7 Battery through a high resistance 33I is duced 60 cycle current traced from ground at
also connected to lead 328 but has no function
at this time. The grounded sleeve 235 of the
toll line therefore is connected through relays
326 and 321 to battery. Relay 326 being margi~
35 nal does not operate because the left-hand wind
ing on sleeve relays 231 and 238 of the toll line
have too high a resistance. Relay 321, however,
does operate and therefore connects ground to
winding relay 3I8 to battery, causing the latter
40 to operate and close contact 3I'I. ,
Another action takes place when relay 306 op- .
crating on its left-hand winding closes the look
ing circuit at its right-hand inner contact
through a separate winding, said winding being
included in a path from ground on talk key 300
traced over lead 332, winding relay 366 and wind
ing relay 323 to battery. The latter relay op
erates in this path and at contact 333v connects
ground to lead 334, which may be traced to lead
50 5I0 of Fig. 5, thence through normal contact on
relay 5| I, lead 5I2, inner bottom break contact
relay 500, lead 5I3 to battery through relay 5I4.
The operation of relay 5I4vat its bottom make
contact closes ground to winding of slow operate
55 relay 5I5, causing ,it to operate and open the zip
order tone circuit to induction coil 502. At the
same time at its left makecontact the operating
transformer 6I6 to front contact and armature
relay 601, thence direct to lamp 6I9 and through
right back contact and armature relay 6I2 to
lamp 62I. The operator knowing this call will 35
be completed by another toll operator inserts the
front cord plug in outgoing jack 661 and restores
her talking key to normal. Sleeve conductor 348
thus connects with sleeve conductor 635 thereby
closing a circuit for cord lamp 344 and for oper
ating relays 631 and 638 over a path traced from
battery through lamp 344, contact 345 on relay
l. J
306 now in its normal position, lead 343 and nor
mal contact 346 on ringing key 341 thence over
sleeve conductors 348 and 635, left back contact ,;
relay 629, lead 636, to ground through right wind
ings relays 631 and 638 which operate. Relay
63'! operating prevents tip conductor 633 from
being grounded and relay 638 connects ground
over lead 639 to winding relay 6'40, causing it to I)
operate. Relay 640 at contact 652 closes a cir
cuit from battery through winding of relay 655
to ground at back contact and armature relay 606
causing relay 655 to lock at its left front con
tact to ground at right outer make contact on -
relay 7640 over right outer normal contact on
relay 632. Relay 655 operated connects at its
right make contact a ground circuit leading to
ground is extended to winding of slow operate
relay 5I6 which again restores the zip order tone . left winding of relays 638 and 631 in series to the
sleeve lead. 636. This being low resistance in
60 circuit and at its left make contact extends
comparisonv with the circuit through the right
ground to winding to slow operate relay 5 I ‘I. Re
lay BI'Ioperates and again opens the ziptone hand windingsv the overall resistance of the sleeve
is materially lower thus causing the toll cord
circuit at its left make contact, operates slow op
erate relay 5I8 which again restoreslthe zip tone lamp 344 to light.
Insertion of the front plug of the cord of Fig. I
circuit and at. its‘ left make contact connects 3 in
jack 661, as just described also removes from
ground to winding. slow operate relay5I I. Re
the talking circuit the pad circuit shown in Fig.
lay 5I I operates and at its bottom make con
tact extends ground to winding relay 500, which
thenoperates and opens the induction coil wind
70 ing 50‘Iand 509 from the talking leads 3I4 ‘and
320 causingrelay 504 to~..release. Relay 500 at.
its top inner contact locks over lead 5I9 to ground
on lead 334v previously traced. ,Relay 500 at its
bottom inner contact opensnlead 5l3 allowing, re
75., lay 5I4 to release, thereby releasing relays 5I5, the toll line from o?ice X and the equiva
lent pad in the toll line to office Z, due to the
operation. of relay I 35. The manner in which 70
relay I35 in the incoming and outgoing ends of
. the toll lines is made to operate follows: Relays
208. and 663 having previously been. operated on
their lower windings and held operated to battery
on the outer make contacts of operated relays 75
246? and 640 respectively, . the circuit is com
pleted for the operation of relays 246. and 646. re
spectively when the cord plug is inserted in jack
661.‘ The path for. relay 246:. is ‘traced from
contact .62‘I‘fonv relay 628 and right back con-. the armature relay 6291to lead I33. As
previously‘: describedthis. causes the equivalent
of ‘relay. I2'I of Fig; 1 to. operate which in turn
5 ground through winding relay 246, windingrelay
251,‘ retardation coil 241, top contact relay 266" closes a ground path traced through normal con
tact ongrelay. I26; bottomarmature and back.
thence over the ‘tip conductor 233 of the incom
ingtoll line, conductors 30I, 35I and 353 of the contact relay I28_and bottomiront‘contact relay
toll cord,. conductor 634' of the outgoing toll line, I27; for operating relay I3I to battery. Relay I3I
operating: also operates relay.I26‘ and thussends a .
l0“ through bottomcontact relay 668, retardation coil connectsignalot
20' cycle—1000 cycle to the tollv
64'! bottom ‘armature relay 646-to- battery either line circuit at‘terminating
o?ice Z.
over lead 656,‘ rightarmature and back contact
relay 6I3, leads 656 and winding of relay 666 or
to battery through marginal relays 662 and 663.
. 1.5... In a similarmanner the path for operation of re
lay. 646>may be traced from ground through
winding relay 646 back over the other side. of the
talking. circuit to battery either through wind
ing of marginal relay 244 of Fig. 2. or through
‘iowmarginal relays 262. and. 263. Both relays 246
andt 646 operate and thereafter. the circuit
through winding relay 246‘ includes marginal re
lays 662 and 663 and the circuit through relay 646
includes marginal relays 262and 263. However,
resistance of relays 246 and 646 is too high
forthe marginal relays just mentioned to oper
ate. Relay 246 at contact 266 closes a ground
path‘ for operating relay 244. over lead 256 and
contact 242 on. relay 2I3. Relay>246 at its top
3Ot1'in1rer‘ contact closes ground to lead 265 traced
further ‘over top armature and contact relay 262,
top: armature and contact relay 260, top contact
and armature‘ relay 263 thence over lead I34
The toll .operator at office Z receives a ?ashing
signalin the same manner as previously described
for the‘ connect-signal received'by the toll opera
tor-atici?ce Y.‘ At‘the 'same time the toll line 15;";
circuit at o?ice Z sends'back an .acknowledgment
signal of 26cycles‘superimposed on 1400‘cyc1es,
alsopreviously described. This signal received at
oiiice Y.‘is.transformed‘into a signal to the't011
line of Fig. 6 wherein negative 43 volt battery is 20315:
connected ‘through .a high resistance to lead I23.
Said "batteryis further traced through relays 666,
Bill and 662 tonega'tiv‘e 24 volt battery causing
relay666zto operate, which closes ground to lead
666v for operating relay 666 to battery through 253::
. lower contact on operated relay 660 and top outer
contact ‘646; Relay 669 looks from battery on its
top‘ inner contact through its own lower make
contact to ground on relay 640 and thus, at its
top outercontact, shunts out resistance seem the
ground. path to lead I34 thereby operating the
equivalent! of relay I20 ‘for disabling incoming
through winding relays I 351and I26 in series to I signals except the disconnect signal. Relay 666"
35 rbattery. In addition to the operation of relay also connects ground over lead 603 through back
I35, which removes the pad from the incoming contact 664 on relay 605 and winding relay 666
end of the ?rst automatic toll line, relay‘ I20 'also to battery. Relay 666 operates in this circuit and
releases relay 650‘because the operating ground
operates thereby removing battery from the wind
for the latter relay is taken from the left-hand
ings of relays I I6 and I 24 of Fig. 1B thus prevent
ioiring ‘any further incoming signals from reaching armature and back contact relay 666 traced fur
the toll line of Fig. 2 except a disconnect signal» ther through contact 652 on the operated relay
646. Relay 650 releasing opens the ground path
which would operate relay I I8. Relay 646; op
erated, at contact 662 operates relay 666‘ over through ,resistance 646‘ to lead I33 previously
lead 658 and right back contact on relay 6I3. Also traced, thereby'causing relay I26. as in Fig. 1
what its top inner contact it closes ground to lead to release and open the connect signal being sent
665 traced further through resistance 666, top to the distant toll o?ice Z. The opening of this‘
armature‘ and contact relay 663, thence over lead signal‘in turn causes the acknowledgment sig
nal, being sent from o?ice Z, to cease and thus
I34 through winding relays I35 and I20- of a cir
‘relay. 606 at o?ice Y to release. Although
cuit similar to Fig. 1 in series to battery. Relay’
ground is thereby removed from winding of relay
;0=.t.I26 being marginal does not operate through re
606%it remains operated on ground through the‘
sistance 666, thereby permitting Fig. IE to re
ceive incoming signals but relay I35 operates and left winding of relay 605, right inner make con
relay 606 and contact 653. on relay 646 to
removes the pad from the talking circuit at the tact
ground. Relay 605 operates in this circuit.
outgoing end of the second automatic toll line.
W'hen‘the toll operator at oi?ce Z answers, order
;5.~1For transmission reasons it is desirable to leave
is returned to the originating toll operator
the pads connected in the circuit when the toll
of‘o?ice X who again passes the called number
operator at office Y has her talking key 366 oper
ated. Under this condition. relays 246 and 646,‘ and the connection is completed to the subscrib
or line by the toll operator in the o?ice Z. This
instead of operating as noted above fail to oper
0~ate due to tip‘ conductor 3!“ in cord circuit of portion of the connection wherein ringing‘ cur
Fig. 3 being connected-straight through contacts
3I5 and 355 on relay 3“ to tipI conductor 352 ‘and
similarly ring conductor 362 is connected ‘to ring
conductor 35.! through contacts 3I6‘ and 356 on
5 \relay 3 I I. Thus, the ground circuit through re
lay 246 described above meets the ground circuit
through relay 646 and said relay fails to operate
thereby preventing the operation of relay I35‘
and leaving the transmission pads connected in
y-‘the talking circuit.
inserting ‘the cord plug in jack 66'! sends a con
nect signal to ‘the toll oi?ce Z ‘by connecting
. groundthrough resistance 64~6=at right back con
tact relay 665; front ‘contact relay; 656 which is
r1 operated “ by relay ‘646;v contact 65I :-of relay 6I3,
rent is automatically connected to the called line
may be in accordance with‘the usual practices in
completing inward connections through the local
13 ‘or cordless 13 board and therefore need not be
describedv here. As soon as the called subscriber
answers, a receiver-off-hook signal of 20 cycles
superimposed on 1000 cycles is sent back over the
built up connection through the toll'cord con
ductors of Fig. 3 in‘ o?ice Y to the outgoing auto
matic toll line in the originating o?ice X.
This signal resuts from the subscriber remove
ing-‘his receiver from the switchhook thereby re}
leasing relay 244- “in: the toll line circuit at office
Z. Ground being removed from winding relay ~
266-‘ at'lfront ‘contact relay 244,‘ allows ground <~
from contact-‘on relay 238 through winding relay
264 to continue to hold relay 288 operated and
thereby also to cause relay 264 to operate. Re
lay 264 at its left contact supplements ground to
right armature and back contact relay 244 for op
erating relay 226 traced through right contact
relay 288, right armature and contact relay 219,
left armature and contact relay 280 to battery
through winding of relay 225. Relay 226 looks to
lead 283 traced further over left outer armature
10 and contact relay 232 to ground at left outer con
tact relay 240. Relay 226 in turn operates relay
280 which locks over the right back contact and.
armature on relay 219, right front contact relay
288 to ground at back contact relay 244 for hold
15 ing the operating circuit of relay 226 open. Relay
226 at its left front contact closes ground through
front contact and armature relay 650, to lead
I33 over a path previously traced. Relays I26
and I21 operating close a ground path‘ for op
erating relay I32 and thus sends out a 30 cycle
1000 cycle signal which passes through the toll
line and toll cord talking conductors and is re
ceived at the terminating toll o?ice Z by the toll
line which is the equivalent of Fig. 1. Said signal
operates the equivalent of relays H1 and I24 in
Fig. 1B causing ground through a resistance I25 10
to be connected over lead I23 through relays
200, EDI and 202 in series to battery. Relay 200
resistance 282 to contact 223 on relay 2I3 and
thence over a previously traced circuit through
relays 228 and 229 to lead I33. This results in
20 the operation of relays I21, I29 and I3I and the
sending of the receiver-off-hook signal of 20
cycles superimposed on 1000 cycles back over the
built up toll line through toll office Y.
At the originating o?ice X this signal is trans
formed into negative 48 volt battery connected
through high resistance I22 to a lead which is the
equivalent of lead I23 of Fig. 1B. Theoutgoing
toll line at office X may be considered as being
identical with Fig. 6, previously described, except
30 that signal control relay 630 is normal.
when battery through resistance I22 is connected
to lead I23 it operates relay 600 which in turn
operates relay 632 in a circuit traced over lead
603, operated right inner. contact relay 685, and
35 lead 654. The operation of relay 532 at its right
outer break contact opens the holding circuit
for relay 655 which in turn releases and opens
a path through the left-hand windings of sleeve
relays 638 and 531 thereby increasing resistance
of said sleeve and causing relay 340 in the asso
40 ciated toll cord sleeve to release and put out
supervisory lamp equivalent to lamp 344. The
operation of relay 632 also sends an acknowledg
ment signal of 20 cycles superimposed on 1400
cycles back over the built up connection to the
45 o?ice Z by connecting negative 48 volt battery
through high resistance 624 to lead I33. This
path is traced further through contact 558 on
relay 640, left outside contact on relay 5I3, left
armature and front contact relay 532, back con
50 tact and armature relay 650, contact 65I on relay
6I3, contact 621 on relay 628, right outer back
contact and armature relay 528 to lead I33. This
signal at office Z terminates the receiver-off-hook
signal releasing relays 600 and 532 at office Z.
55 Release of relay 532 then terminates the acknowl
edgment signal and the completed connection is
ready for conversation.
If the originating toll operator at office X,
whose toll cord is identical with Fig. 3 and toll
60 line is identical with Fig. 6, wishes to recall the
toll operator at the terminating office Z she op
erates ringing key 341 which thereupon releases
relay 631 due to breaking ringing key contact 346,
thus introducing high resistance 358 in sleeve
65 lead 348. At its top contact key 341 connects
ground through tip conductor 354 which is fur
ther traced over what would be lead 610, back
contact relay 631, right inner armature relay
640, and ?rst make contact to battery through
70 winding relay 650. The front contact of the
latter relay prepares a path for sending out a
' recall signal of 30 cycles superimposed on 1000
cycles, traced from 48 volts through low resist
ance 618 front, contact and armature relay 605,
being polarized does not operate and relay 282
being marginal operates only on direct ground.
Relay 2PM although marginal operates on this 15
resistance ground and closes direct ground from
back contact relay 202 to lead Z'II armature and
front contact 212 of relay 2E3, winding relay 213,
contact 214 on relay 215 to right winding of sleeve
relay 238 thence over the sleeve to battery through 20
toll cord lamp 384 as previously traced. Relay
213 operates in this circuit and locks to the toll
cord sleeve and to relay 215. Relay 213 at its
left contact closes ground through interrupter
216 to winding relay 215 and to left winding relay 25
211 in parallel to battery causing both of said
relays to operate. Relay 215 thus follows the
interrupter 216 thereby opening and closing the
lead to right winding relay 236 and causing the
toll cord supervisory lamp 304 to ?ash indicating 30
a recall signal. The toll operator at oflice Z upon
throwing her talking key 380 causes the sleeve
resistance to be increased thereby releasing relay
213 which in turn releases relays 215 and 211
and retiring the flashing lamp. The re-ring sig 35
nal continues only as long as the originating op
erator holds the ringing key open.
When the called subscriber in of?ce Z discon
nects, a receiver-on-hook signal is sent back over
the toll line which is received at office X as 40
ground through a resistance over lead I23. This
operates relay Bill and in turn relay 855 which
looks to relay 632 over a path traced from ground
at right contact relay 540, right back contact and
armature relay 532 through left armature and 45
contact and winding relay 655. Relay 555 at its
right armature and contact closes ground to left
winding of sleeve relay I538 which lowers the
resistance of sleeve lead 636 and lights operator’s
toll cord lamp 344 as previously described. Relay 50
SUI also sends an acknowledgment signal of 20
cycles superimposed on 1400 cycles by closing the
circuit traced from 48 volts battery through high
resistance 624, contact 656, relay 648, left outer
contact and armature relay BI3, left armature
and contact relay 68L back contact and arma
ture relay 650, thence over previously traced path
to lead I33 which results in the operation of
relay I29 and therefore the sending of the ac
knowledgment signal. This signal when received 60
at office Z by the toll line terminates the re
ceiver-on-hook signal which thus releases relay
20I. Relay 20I released terminates the acknowl
edgment signal.
If in building up the connection the toll line
at o?ice Z encounters an all-trunks-busy or sub
scriber’s-line-busy or if later on during conver
sation the call subscriber wishes to attract the
original operator’s attention by flashing his re
ceiver on and off the hook the receiver-off-hook 70
and receiver-on-hook signals will be sent back
over the toll line in the same manner as is
done in the case of the subscriber answering and
disconnecting described above. If the called sub
scriber should ?ash very rapidly, a receiver-on
hook signal will be transmitted and until the
acknowledgment of the signal is received, further
motion of the switchhook will be ineffective. If
the receiver is off the hook when the acknowledg
ment signal is received at of?ce Z relay 244 re
leasing opens the holding circuit for relay 219.
Relay 219 at its right back contact thus closes
the circuit for operating relay 226 and traced
from ground at left front contact relay 264,
10 armature and back contact relay 244, right con
tact and armature relay 263, right armature and
back contact relay 210, left armature and back .
contact relay 280 to battery through winding
relay 226. Relay 226at its contact 28I con
nects ground to winding relay 280 which in turn
locks to ground over the circuit thus traced to
the right back contact relay 244. Relay 226 at
‘its left make contact also connects ground
through resistance 282 to right inner armature
20 relay 2I3 and thence over a previously traced
circuit through contacts on relays 2I3, 228 and
229 to lead I33 for sending a receiver-off-hook
signal back to the originating toll operator. This
in the same manner will render further motion of
the switchhook ineffective until its acknowledg
ment signal is received. When the subscriber
stops ?ashing, if switchhook is in the same posi
tion corresponding to the last signal transmitted,
no further action will take place; but if the
30 switchhook is in the opposite position then a ?nal
signal will be transmitted. From the above it.
has been made clear that no matter how rapidly
the subscriber ?ashes ?ashing signals will be
transmitted to the calling operator and a correct
indication of the position of the subscriber’s
switchhook will be given when the ?ashing ceases.
These voice-frequency signals of 20 cycles-1000
cycles and 30 cycles-1000 cycles, respectively,
being connected directly to the talking circuit
pass through the toll cord and associated auto
matic toll line circuits at the through toll oflice Y.
They also, of course, are received in the associated
receiving circuit equivalent to Fig. 1B but are
made ineffective due to the operation of relay
45 I20 in the Pad circuit equivalent to Fig. 1A pre
operated connects ground directly to lead I33
‘through right outer break contact on relay 629,
thereupon operating both relays I21 and I28 in a
circuit the equivalent of Fig. 1. Relay I26 being
normal connects ground through bottom arma
ture and front contact relay I28 to battery
through winding relay I30 which operates and
prepares a path for the 45 cycle-1000 cycle dis
connect signal. Relay I30 in turn operates relay
i2‘0 which thus completes said signal path to 10
the toll line.
The disconnect signal is received both at of?ce
Y and o?‘lce Z in a circuit the equivalent of Figs.
1 and 2 and results in operating relay II8 which
thus connects direct ground to lead I23 through 15
the back contacts of relays I24 and H0. This
ground path is further traced through windings
of relays 200, 26I and 202 in series to battery.
With direct ground so connected, both relays‘ 20I
and i202 operate. Relay 202 operates relay 229‘ 20
through contact 284 on relay 2l3. Relay 229 thus
transfers the sleeve of the associated toll cord
from ground through relays 23'! and 238 to 48
volt battery through its own right Winding. Re
lays 23? and 238 thereupon release, in turn re 25
leasing relay 240. The operation of relay 229
connects 43 volt negative battery through high
resistance 224 to lead I33 as an acknowledgment
signal all in a ‘manner previously traced; oper
ates relay 232 from ground at its left inner make 30
contact; and holds relays 205 and 2I3 operated.
The operation of relay 232 removes ground at its
left inner contact for releasing relays 205 and 206
and in turn relay 2I I. When relay 229 operated,
the 48 volt through its own right winding, being .1 35
connected to sleeve lead 235 and the associated
toll cord sleeve 302 and lamp 304, causes lamp
304 to light as a disconnect signal the same as if
direct ground were so connected. Since the dis
connect signal is received at both of?ces Y and Z
it follows that the cord lamp 304 at these o?ices
both light as a signal to the operator to discon
nect which they proceed to do. When relay 229
operated and caused an acknowledgment signal
to be sent back on the line this signal at o?ice X 45
viously described. Thus, in building up connec
causes the disconnect signal to terminate as ex
tions over automatic toll lines it makes no dif
ference how many intermediate o?ices the call is
plained below. The termination of the discon
nect signal at of?ce Y thus releases relays 20I
and 202 and in turn- relay 229. The release of
relay 229 releases relays 205, 2I3 and 232 restor
ing the circuit to normal. The automatic toll line
between o?ice Y and office Z likewise restores to
routed through because at all through-points
the Pad circuits are removed and the incoming
signalling circuit is disabled except for the dis
connect signal which Will later be described. At
the originating and terminating toll o?ices', how
ever, the Pad circuits are not removed and the
normal in a similar manner.
As mentioned in a previous paragraph, an
apparatus for receiving and sending signals is -acknowledgment signal was returned over the
operable at all times.
When the calling toll operator at office X dis
connects, a disconnect signal consisting of 45
cycles superimposed on 1000 cycles is caused to
be transmitted to the built up toll line. The cir
cuit arrangement for doing this may best be de
scribed by referring to Figs. 3 and 6 which may be
assumed to represent the outgoing toll line at
o?ice X. The toll operator upon removing the
cord from the equivalent of jack 661 releases
sleeve relays 631, 638 and relay 660 connected to
the ring side of the talking conductors. Relay
638 removes ground from winding relay 640 caus
ing it to release. Relay 628 then operates in a
70 path traced from battery at left back contact
relay 640, winding relay 628, front contact and
‘armature relay 6“ to ground at contact 6I0 on
relay 606, which still remains operated from
‘ground at right inner armature relay ‘632 over
113,75 leads 63I and 630, previously traced. Relay 628
toll line to the toll o?ice X which causes relay
II6 to operate and in turn operates relay II9.
The latter relay connects 48 volt negative battery
I2I through high resistance I22 to lead I 23 and
operating the equivalent of relay 600 which in 60
turn operates relay 632. The latter relay at its
right inner contact removes the ground that has
continued to hold relays 606, SH, 628 and 655
operated. These release and in turn release re
lay 608. The release of relay 628 terminates the 65
disconnect signal which at offices Y and Z re
sults in terminating the acknowledgment sig
nal being received over the toll line. Upon ter
mination of the acknowledgment signal at office
X relays 600, 605 and 632 release thus restoring 70
the circuit to normal.
If it be assumed that the toll operator at
of?ce Y pulls down her toll cord connecting the
two toll lines before the calling operator at office
X disconnects, a pulled down signal of 45 cycles
and relay
632. The
606 which
and 611.
relays 605
1000 cycles is caused to be sent back over the toll
line to o?ice X as described above, due to the
release of relays 231, 238, 240, 244, 263, 264, 219,
280 and the operation of relay 228. When this
signal is registered and acknowledged by the
toll line equivalent to Fig. 6 at office X sending
back the 20 cycle-1400 cycle signal as will fur
628 operates, in turn releasing relay
operation of relay 632 releases relay
in turn releases relays 6II, 608, 628
Relays 628 and 611 released, cause
and 632 to release, thus restoring the CH
circuit to normal all in a manner as previously
Connection between automatic and ring-down
ther be described, said signal operates relay H6
in a circuit at office Y equivalent of Fig. 1B.
toll lines
Relay II6 operates relay II9 thus connecting
negative 48 volt battery through high resistance
It is now assumed the called number was such
I22 to lead I23 for operating relays 290 and 232.
The operation of relay 232 releases relays 206,
that it required the connection to be completed
over the ring-down trunk of Fig. '1 instead of
2| I, 228 and 208.
over the second automatic toll line of Fig. 6.
The release of relay 228 termi
15 nates the disconnect signal which at office X
The call having originated at office X and
causes the acknowledgment signal to terminate
which in turn at office Y causes relays 200, 205,
2I3 and 232 to release, restoring the incoming
end of the toll line at oflice Y to normal.
Under the assumption that the toll operator
at o?ice Y pulled down as above described and
caused a disconnect signal to be sent to the toll
line at office X, which for the purpose of this
come in over Figs. 1 and 2 at office Y is assumed
to have been answered by the toll operator insert
ing the rear plug of the toll cord of Fig. 3 in
jack 248 of the automatic toll line of Fig. 2 as
previously described. The operator at this point
received the wanted subscriber number from the
originating toll operator, requiring that a con
nection be established over a ring-down trunk
such as the one shown in Fig. '7. The insertion
description may be assumed to be the same as
25 shown in Figs. 6 and 1, this signal causes relay
H8 to operate and connect direct ground to lead
I23. Relays 60! and 602 operate in said circuit.
Relay 602 connects ground over lead 61I, arma
ture and back contact relay 6I3, winding relay
30 613, contact 614 on relay 615 to left winding
sleeve relay 638, thence over sleeve lead to battery
through cord lamp 304. Relay 613 at its right
contact locks up to the sleeve lead when relay
215 is normal or to battery through resistance
685 when relay 215 is operated. Relay 613 at
its left contact operates relays 615 and 611 from
ground through interrupter 616. Relay 611 locks
to ground at contact 6I0 on relay 606 traced
through armature and front contact on operated
40 relay 6II, thence through contact 686 on relay
6I3 to battery through armature, contact, and
left winding relay 511. Thus when relay 215
operates on the first ground period of interrupter
616, it opens the lead to left winding of sleeve
relay 638, thereby allowing the sleeve relays 638
and 631 to be held over a high resistance path
which extinguishes the operator’s toll cord lamp
304. When interrupter 616 opens the ground
path to release relay 615, a low resistance ground
50 path to left winding of relay 638 is again con
nected which causes toll cord lamp 304 to light.
Thus the operator’s cord lamp ?ashes in accord
ance with the period of the interrupter and in
forms her that the connection has been pulled
Relay 60I being previously operated as de
scribed above closes a path for sending back an
acknowledgment signal to the toll line in office
Y, said path being traced from 48 volts through
high resistance 624, contact 656 on relay 640, left
outer contact relay 6I3, right armature and con
tact relay 60I, back contact and armature relay
650, thence through previously traced path,
through contacts on relays 6I3, 628 and 629 to
65 lead I33. This closure of 48 Volts to lead I33
results in sending an acknowldgment signal
back to office Y which, when it is received, termi
nates the pulled down signal in a manner as pre
viously described. The termination of the pulled
70 down signal thus releases relays 60! and 602.
Relay 60I released in turn terminates the ac
knowledgment signal. The toll operator then
disconnects and if necessary reorders the called
number as on a new call.
When the toll operator
7. disconnects, relays 631, 638, 640 and 660 release
of the front plug of the toll cord in jack 100 in
addition to extending the talking conductor 353
to 103 and conductor 354 to conductor 104 closes
the sleeve circuit. Assuming the talking key of
the cord operated at this time, said sleeve circuit
is traced from battery at contact 404 of key 405 30
in operator’s dial circuit of Fig. 4, through battery
contact key 40I, lead 406, contact 336 on relay
331, through winding of relays 339 and 340 in
series, contact 342 on relay 306, lead 343, contact
346 on key 341, lead 348, thence over sleeve lead
105 and upper winding relays 106 and 101 in
series to ground at contact 103 on relay 109. Re
lay 106 operated, connects ground to winding
relay 109 to battery at contact 1I0 on relay 1| I.
Relay 109 operated, connects ground at its right 40
contact to winding relay 1“ to battery. Relay
101 performs no useful function at this time and
releases as soon as relay 109 operates and con
nects ground through resistance 1I2. Relay 109
at its right inner contact opens the circuit 45
through winding relay 1I3 to prevent false opera
tion of the latter relay. Relay ‘III in operating
at its left outer contact removes the termination
1I4 from across._the tip and ring and at contact
1I0 removes battery supply for relay 109. Relay 50
109 releases, reducing the sleeve resistance to
normal and permitting relay 101 to reopcrate.
Relay 1II at its left inner contact connects bat
tery to winding relay 124 to ground. Thus relay
124 in operating releases relay 129 and extin
guishes idle indicating lamps. 125, 126 and 121
which may be assumed to have been dimly lighted
from ground through transformer 128 as de
scribed for the automatic toll line circuit of
Fig. 2.
The operator then throws ringing key 341 for
calling in the distant operator. Said key, in ad
dition to placing the termination 359 across the
calling end of the toll cord, connects ground to
the tip conductor 354 and its bottom contact346, 65
opens the shunt around resistance 358. The
sleeve circuit previously traced is thus now traced
through resistance 358, top inner contact relay
3II to sleeve lead 343. This increase in sleeve
resistance releases relay 101 which in turn closes 70
a path for operating relay ‘H3. Relay 1I3 oper
ated closes a path at contact 1I5 for operating
ringing relay 1I6 traced from ground at top con
tact ringing key 341, leads 354 and 104, contact
1I5 on relay 1I3, lead 1I1, armature and front 76
’ contact of normally operated relay ‘IIB, ‘through
winding relay ‘H6 to battery. The latter relay
operating closes a circuit at its front contact from
‘ground and ringing generator ‘H9 over leads ‘I20
and ‘HI to toll line conductors ‘I22 and ‘I23, re
spectively. In this manner, ringing current will
continue to be sent out over the toll line as long
as the ringing key is held operated.
The distant operator upon receiving a ?ashing
line signal in the manner similar to that de
scribed for Fig. 2 answers by inserting the rear
plug of an idle cord in what would be the equiva
lent of jack ‘I02 of this circuit. The ringing key
341 of the toll cord having now been restored to
'15 ‘normal, relay ‘H6 is released, thus preparing a
circuit for the ring-down relay ‘I30 so that when
a distant toll operator rings at any subsequent
time, relay ‘I30 will operate and at its back con~
tact open the circuit for relay ‘H8 to release and
connect ground to lead ‘H1. Ground on the lat
ter lead operates relay ‘I3I through contact ‘H5
on relay ‘H3.
Relay ‘I3I at its right outer con
tact connects ground through winding relay ‘I32,
‘ 125
normal contact on relay ‘I33, right outer contact
on operated relay ‘II Ii, thence through lower wind
I20, however, being marginal, does not operate.
Thus all supervisory signals are terminated on
the incoming automatic toll line and the toll
operator receives supervision from the calling
If the connection is completed to a tributary
ring~down toll line, the operation of the auto
matic toll line circuit is the same as described
for a263regular
of Fig. ring-downtoll
2 also operatesline
and except
the circuit to lead I34 so that the associated pad
circuit cannot function to cut out the transmis
sion pad.
Connection between automatic toll line and talk-5i
switching ‘trunk
‘ 5
Assuming now that the incoming call over the
automatic toll line at o?ice Y from the originating
toll of?ce X previously described requires that the
connection be completed to a subscriber in aif‘go
manual office. In this case, the toll operator of
o?ice Y inserts the front plug of the toll cord of
Fig. 3 in jack ‘800 of a trunk to» a manual oflice
shown in Fig. 8. Trunks of this type are pro
vided with a single lamp which serves as a com-"1525
ings of relays ‘I11 and ‘I06 to sleeve 105 to battery
bined answering and idle indicating lamp.
in toll operator’s cord circuit. Said path being of
low resistance causes the operator toll cord lamp
‘344 to light. Y'I‘he operation of relay ‘I32 looks
through its left contact to the sleeve circuit and
serves as an answering lamp on incoming record
, at its right contact connects ground through a
' ?ashing interrupter ‘I34 to winding relay 133 to
ing completing calls and as an idle indicating
lamp for outgoing tollswitchingtrunk calls. Thus
in completing the call here described, the tollii’30
operator will observe one of the lamps 80I burn
ing dimly in a circuit traced from ground on
battery. The latter relay, following the intermit
tent interrupter ground, opens and closes the low
resistance sleeve ground causing the toll cord
transformer 802, front contact on operated relay
lamp 344 to ?ash on and off in accordance with
because ground at 805 must be connected to lead
‘ the interrupter ‘I34.
806 through contacts 807 on relays in the preced
ing trunks. To do this, each relay equivalent to
relay 808 in each preceding trunk must be oper
ated that is, be in a busy condition. Also, relayl40
The toll operator, upon
throwing her talk key 32! increases the resistance
, of the sleeve suiliciently to release relay ‘I32 the
next time relay ‘I33 is released. In this way the
‘toll cord lamp is extinguished.
The pad control arrangement shown in Fig. 7A
. is normally in the line leading to toll line re
;peater ‘I35 and is cut out only when the two
‘circuits arranged for pad control are connected
‘together directly as in this case where an auto
matic toll line is connected to this circuit through
j a toll cord with the talking key in normal posi
tion. This transmission pad is cut out due to re
lay “136 being operated from ground in series with
the upper winding of retard coil ‘I3? to line con
ductors ‘I48 and ‘I04, thence over cord conductors
‘ 354, 352,302A, 302 and 234 to lower contact on
operated relay 208 in the toll line of Fig. 2, lower
755 winding of retard coil 24?, contact 26I on relay
246, thence through winding of relays 262 and
‘263 to battery. Battery through winding relay
‘I38 may likewise be traced back to ground on
winding of relay 246 but relay ‘I38 being marginal
does not operate. Thus a path is established for
operating relay ‘I30 traced through its winding,
contact on operated relay ‘I31, through armature
and contact on relay ‘I38 to ground. Relay ‘I39
being operated is arranged to disconnect the pad
165 by short~circuiting resistances ‘I40 and ‘MI at
contact ‘I42, short-circuiting resistances ‘I43 and
"I44 at contact ‘I45 and opening bridge circuit ‘M6
at its top break contact. The pad associated with
the calling automatic toll line is likewise cut out
, due to ground being connected by relay ‘24B
through‘resistance 206 and normal contact on re- ‘
‘lay 263 to lead I34, thence through relays I35
and I20 to battery. Relay I35 operating in the
circuit thus traced cuts out the pad circuit in the
same manner as did relay ‘I39 of Fig. 7. Relay
803, right back contact relay 804, through lamp
80! to ground. This lamp indicates an idle trunk535h5
808 in this particular trunk must be normal be
In this manner,
cause the trunk is not in use.
ground at 805 operates relay 803 individual to this
trunk, thereby causing lamp 30! to light over the
path described above.
When the toll operator plugs into jack 800 and
the operator is not connected at the local of?ce,
sleeve relays B09 and M0 operate in a path traced
from battery through lamp 344, contact 345 on
relay 306, lead 343, contact 346 on key 341, sleeve 50
lead 348, thence over sleeve 8I I of the toll switch
ing trunk and through left winding relay 809 and
right winding relay M0 to ground. Relay 809
opens battery from lead 8I2 and relay 8I0 oper
ates relay 8| 3 over a path traced from ground 55
at its own front contact through winding relay
8I3 to battery. Relay 8I3 at its left inner con
tact connects battery to lead 8I4, traced further
over lead 8I5 through winding relay 8I8 to
ground at bottom break contact on relay 8 I ‘I, thus 160
operating relay 8I6. The latter relay through its
continuity contacts connects an obvious battery
and ground circuit through windings of relay
8I8 and contacts on relay 8I9 to the trunk con
ductors 820 and 82I connecting with the distant ‘65
manual of?ce. The closing of said circuit causes
a suitable signal to be given to the B operator at
the local manual of?ce in accordance with well
known practices for this tra?ic. Relay 8I8, how
ever, does not operate at this time.
Plugging a toll cord in jack 800 also closes a
path for operating relay 822 traced from positive
battery 243 through relay 244, contact 242 on re
lay 2I3, contact 245 on relay 246, through lower
winding of retard coil 241, lower contact 'relay- 1'16
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