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70d. .1, 19466
‘
M, E, MALONE-Y
-‘ _ 2,408,432
TELEPHONE SYSTEM
Filed May 23, 1945
2 Sheets-Sheet 1
TE 'EWMEFY
TRUNK
2
I
668
'N04
M1A'RK0ER
//v ENTOR
M E MALONE Y
C. WLWO
A TTORNE V
Oct. 1, 1946.
M. ‘E; MALONEY
TELEPHONE SYSTEM
Filed May 25, 1945
T.
2 Sheets-Sheet 2
Q
Ar
maw.
3$5% SN
By
lNVE/VTOR
M 5 MALO/VEY- >
.c,
ATTORNEY
2,408,432
Patented on. 1, 1946‘
2,408,432,.
’
TELEPHONE S‘ESTEM‘ '
Martin. E. Matlonszo FlushingtN. X3, assignor to.
~ Bell. Telephone Laboratories; lnccrnorated,
New .York, .N. Y”, a,...corpor_ation. oihtemYQIk '
Y _ Application-May
1945,_~ Serial No. sssgscr
‘ , 11 Claims.
(curse-121)..
1
2
r 'Thisinvention relatesztotollatelephone systems
trunk: and a rehuntsisnai- is transmitted; to; the
and has iorritsobjectuto facilitate the completion:
ofv toll- connections. during busy ‘calling ‘periods.
sender; , The rehunt signed causes the sender-te
.
0. Myers. ?led. August. 1:8; 19.44, patented Aug. '14,
194:5; .No. ‘2,382,393;
arrange. its circuitsrtc receive. ‘pulses. from the
outgoing and oi. the trunk‘ and also- to ‘prepare.
to: transmit, it necesseryi. the. proper designation
for extending the. call. to .an. .cnereim'sv ‘position
at-thewianted .o?ice...‘
These, and other features of the inyentionsrzill
be..more~clear1y understood from a consideratim
In1that application’ vis shown a.’ toll. . emce
of, > the following .rlescription mead in connection
More speci?cally, the invention contemplates
anzimprovementon the automatic switching an.
rangements disclosed. and claimed in the patent
application, Serial, No. .5150;0'Z:0,,.of B. "McKim, .and
with the-drawings, in ‘which:
ell-nipped‘v
automatic.’ switches of :the cross
Fig; 1 .showsta'psrtsoi
incomins trunk cine
bar »type,__ in which calls incoming’ to the oilice
cuit. and. an .cner?cw? trunk-.andcode. generator
areextend'ed to. toutgoing trunks :under the: con-o
embodying: the *present‘inventicn: and,
tmioi register" senders and markers, the ‘former
of .a sender and-a :merlier
of which receive the designation ‘of the wanted 15? vFig. 2- show
subscriber either-directly irom: the local: tol'l-oper» Y" iorcarrying: ontrlthe restores of. theinvention.
The drawings are, in part, skeletenized shew!
ator- or over ‘the: incoming trunk‘ from- the toll‘
operator at. the. calling vomce.
»'
ings- of‘ the circuits of: theaters-mentioned.snpli- .
'
cnticnctMcKjmsndMyera; ,Reierencc is made
During iperiodssof snormal: itrai?c, the ‘markerv
receiysesthe- designation or the wanted. o?icewf-rom
tnrthatcanplicationior a. disclosure of thev some
Piste. equipment .and. where pnssible thev same
the sender, tests. tor and selects an idle trunk‘,
~ reference @charaeters here.
outgoing to ‘that; o‘?ice, operates‘ the: necessary
crossbar switches to; connect the- incoming trunk
With;_,:the..se1-ected outgoing trunk and releases;
employed.‘
erencennmeralslessthanimt‘hiindred identify
added ecminmenhv
having: given. the sender .anyxinformation neces 25 ' .Anincoming callyover a trunk; such sis-shown
sary :tior its further -.operation. ‘However, ‘all? ' at the-:ieitcfi‘ig. 1, isrindicated'hvtheconnection
of ground to-conductor 1:00: iII‘LESPOBSe tothe
of. the inunks Loutgoingtd. the wanted oi?ce tare
operation ofv a. composite. signaling circuit snot
.busy,>f the 'rmarker connects _ the '- incoming; :trunk'
‘ showmsmnder thezccntrolact the-calling:toolcpere‘
to one .lof a ‘number ;of1 over?ow trunks, individual?
to
‘wanted. group of‘ioutgoing trunks, over‘ 30. ator-at‘vthe distant of?ce. Ground on conductor
mo, completes; a circuit: extending: over .11» back
which the calling toll‘ operator receivesa ?ashing
contactoi relay $20: to; :therwindins. 0f ~1re1a~y 618.
and battery. Relay 15283010585: arr-obvious circuit
for relay ‘5221 which. looks. inc-ground sityits own.
over?ow :signal. When an outgoingv trunk -be-.
comes; idle, the rate \of flashing; 'i's changed-to
indicate a reorder and the calling toll operator;
. contact, closesia .holdina'nircuitt for Tel-a3! .521 ‘to:
conductor’ 1 001,. and connects ground 1W6‘! a back
‘ contactacf relay 452D to. conductor 1658.1;0 operate
mayi'make :a new ..attempt. to ‘complete the call.
insaccordance :wi-th-the present invention means
is iproyided'whereby-ywhen a callhas been directed‘,
the over?ow ‘itrunk' v'ito automatically" transmit the
the linkzstartzrelay- :200. and: :cause the, operation
of they sender ili-nk 20%]. to, vconmact.'1'.'l:\e..itrnnkwqi
Ei'g. l-withan- idle sender such asqthe nnesherm
designation of the outgoing trunk group- tepid‘;v
in-partiin Fig.2..
sender connected with the associated-incoming
‘When this connection is completed, :a circuit
is: ‘closed from ‘battery through the, "windings. ;of
to an over?owtrunk; the release of one of‘ the
corresponding group of outgoing trunks causes‘
trunk.
Anotherieature or the invention ‘lies in means '
for-‘transmitting the'recrder signaT-to a plurality:
of incoming trunkstogether with means tonsso
ciaéte ‘the designation transmitting- means within
single calling trunk, changing the ‘reorder signal
back- to an over?ow's'igna-l =f'or the-other caliing
.
.
relays - “Brand: 1315', conductor 680 ‘through
link-L201 .eto; conductor 12.4.54 and thence/over
45: ', sender
a =.back.1contact.¢oi relay ?ltsywindingsnof relay
“034:0 groundkat the hack. contact ofrrelayIl-ltl...
Relay ?nloperatesdn this-circuit zbutrelays .688;
andi l-il cannot, .due toLthe ‘high resistance vacf: :the
5.0. left winding ‘of I‘ relay 2M3. Relay- “2503 -;nperates.
relay 2402 ‘which operates- .relay' 24M‘ .and. scene
nects..-.a substitute ~~gro1md to. vthe Jisht winding
to set-up a record in an incoming trunk when
of relay ‘Mus.v Relay'ilm- connects ground
that trunk has been connected toan over?ow
conductor. .2 455. whichextendszthmngh. theisender '
trunk. When-the v-operatorrering's in response :to
link 2015 to conductor £64. ‘fwmdingof relay 620
the reorder signal, a .sender' is attached ‘to ‘the
trunks.
'
1
‘
'
Another feature of the invention- lies in means
‘
3
functions of the over?ow circuit. In addition it
connects ground to conductor I02 to mark this
over?ow trunk busy to any marker which may
and battery. Relay B20 operates, locks under the
control of relay 62I and opens the start circuit
of the sender link which is now held from the
After the sender has received the class informa
tion from the trunk and adjusted itself in accord
be testing in this group.
In the sender, the connection of ground to the
simplex circuit causes the release of relay 2‘IIO,
ance therewith,“ to". receive the incoming" pulses,
relay 26 III is operated, gshort-circuiting the ‘high
closing a circuit from ground over the back con
tactof‘re'lay 2;‘I‘I0, front contact‘ of relay 2809 to
sender.
,
the winding‘ of relay 2109‘ and battery. Relay
resistanceleft"winding "of relay 2403 to ‘permit
relays B00 and EH5 to operate. Relays 609 and
2709 opens the operating circuit of relays 609
- and 6I5, causing these relays to release.
M5 disconnect the incoming and outgoing line
Since
conductors, relay 609 extending the incoming
conductors of the upper channel to conductors
relay 202- was operated to tell the sender that
the call had been extended to an over?ow trunk,
EBI and 682, while relay 615 ibridges resistance
632 across the incoming tip anclvrinlg'v‘ conductors
as ‘soon as relay Y6I5 releases, relay 2109 closes
a circuit from ground over its front contact, front
contact of=relay 202, through the sender link 20I
of the lower channel. The outgoing tip‘ and ring‘
conductors of the upper channelijareconnected
t0 conductors 535 and 668 while those ,ofthe
_ to conductor-665, back contact of relay 6I5, nor
mallcontacts and winding of relay IOI to battery.
lower channel are connected to conductors 631"‘
and 608.
.
_
20
5- The- operationaof the sender in‘receiving the
number‘of the wantedisubscribe'r and transfer
ring theb?ice code ltoa marker takes place .as
described in the above-identi?ed .McKim-Myers
Relay IOI locks to ground at a back contact of
relay 6l5. With relays 609 and 6I5 released the
over?ow trunk is connected to the incoming trunk
and the over?ow ?ashes are transmitted to the
originating oi?ce'.
The release 1~ of the- sender
takes’ place as ‘described in the above-identi?ed
The ‘marker identi?es 1 the group of
McKim-Myers patent; In the‘manner-‘above dee
trunks leading'to the .wanted of?ce and attempts
to test them, In the manner setforth in the
McKimlMyers patent, if'all of they trunks 'I are
busy; a relay such ias..relay>:402, isi-im'mediately'
operated which causes the. marker.‘ to test for. an
scribed, one to three other incoming trunks may
patent.‘
idle over?ow trunki‘an‘d operatethe. outgoing
be connected over contacts of relays I3I,-:I33;‘
etc. .to the over?ow trunk of this group. '
'
When one of the outgoing trunks,fin the group
. associated with the over?ow'trunk of Fig. 1,'be
comes idle, the rate of the ?ash transmitted over
the-trunk is changed as a reorder signal. As
above noted, as many as- four incoming trunks
link switches 500 to connect theincoming trunk
Wlth'theiDVel‘?DWitl‘lll'lk'at the right ofFig. 1.
The operation. of relay 402-Ialso transmits. a sig
nal to ‘thesender which: operates- relay2l202 to
tell-the- sender that -the"call hasnbeen extended
may be connected to the over?ow circuit, each
one having a pair of relays like relays-I20 and
I30; Conductor I01 to which'the'?ashing "ground
to an over?owtrunk. :
is‘ connected extends in parallel over‘ back cone
_
’
a
‘
A
-. -.
tacts of relays I30, vIll, I33..;to:'the trunks‘ con-~
nected thereto and therefore four calling toll 0p
and found it idle itconnects ground‘to ‘conductor
I02, ‘closing’ a 'circuit‘over a back ‘contact of- relay 40. eratorsgmay observe the reorder signal'and op-'
crate their compositesignal circuits to attempt
I'03"'to the winding of ‘relay I04 and battery.
to seize the trunk‘ which has, become idle.
Relay I04 connects battery through the winding
“After the marker has'tested the ‘overflow trunk
o'f'relay I03 over a front contactv of relay I04
and a make-before-break contact ofarelay I03
to the'simplex circuit over. the'slower channel of
the .trunk,'t-hrough switches 500 and contacts of,
relay16I5
1' ‘When the
to marker
conductors
hasfcornpleted
631.and 668.
its ifunction
.
;-' In the trunk circuit of Fig. l, relays ‘620 and
62I are locked. Therecall'operation' momentarily
removes groundfrom- conductor I00 releasing and
reoperating relay 628.. While relay 628 is re-"
leasedLit, operates relayy605 overv a back- contact
of relay 6I5. Since relay 'IOI was operated and
operatingirelay 250I.' Relay 250I. operates»,=.locks ;
and closes a circuit-from ground over its lower
locked, relay 6.05 now locks over the front contact
of ‘relayv IOI and this locking ground is extended‘
over'a second‘ front contact of relay IOI to the
éontact,~uppe'r winding of relay ‘2H0, 'ove'r con
start conductor 663, operating the'senderlinkto
thelmarkerrelease relay 203 is operated, in. turn,
ductors 2353 and 235cm parallel, through the
sender link to conductors 56‘! and 668. If: the
connection has been .completed,_relay-2'IIO op
connect a sender with the trunk-asp'reviously
described.
'
,
-
1
-
'
..;
‘Since relay $20 is locked to ground at ‘the con
tact of relay 62-1,, ground appears on-conductor
6.64 which is extended through the sender link
20I to conductor 2455 and over the back contact
of relay, 2,402 to the‘ winding of relay 204 and»
erates,‘ in'turn operating relay'2809 which op
erates, locks; and connects the .low resistance
lower ‘winding of relay 2'll0'in. parallel with‘ the‘
upper winding 'of*relay~21l0, reducing the re-'
sistarice' in series withirelay I03'sui?ciently to 60 battery. »Relay'204 operates ‘in-this circuit and
_ permit that relay to operate. Relay" I03‘ locks
looks so that it remains operated after relay 2402
opens its-operating circuit.‘
~
I
c 7
undertthe'control of relay IMandzextends the
When relay 26H operates, with relay 20,4 op
simplex circuit'through resistance I05 and the
grated, a circuitv isv closed from ground in the
back. contact of relay- I30 ‘to conductor‘ ilifl'to'
which "interrupted ground‘i's connected, at a rate
to" indicate an over?ow condition, by the over
?ow :circuit‘." Relay I03 also connectspthe tip
and ring'conductors of the lower channel through‘
' alternating current receiving circuit 206, front
contact of relay _26I I,-'fron_t contact of relay 204.,
winding of ‘relay 205 and battery; Relay 205
disconnects the receiving circuit 205 from-the in
coming end of the trunk- and-connects it to con-;
condensers’l 08 and IDS-and over contacts of relay
I30 to conductors III! and III leading to a jack 70 ductors 2350 and 2353, ready to receive pulses‘
atithe‘ delay quotation board, the operation of
which is fully - disclosed'in ~the McKim-Myers,
patent,» previously ‘mentioned, Relay I03 also
connects ground‘over the back contact of relay
from the‘ outgoing end of‘ the trunk.‘ Relay 205
also" connects battery and ground to conductors
2352‘and
: Whenrelays
235I. 609
‘ ' and GIS are ' operated
Y,
in the
I30 to conductors II2 andl~IiI3>tolrcontrol ‘the 7-5: manner above described, they ‘release; relay I0, I
2,408,432
7
8
vided in connection with trunk groups requiring
releasing from said‘ incoming trunk, over?ow in
more code digits.
dicating means operated in vsaid trunk prior to
the, release of said control equipment if said trunk
, What .is claimed is:
'
r
_
,
_ 1. In a telephone system,~a toll o?ice, trunks
is connected to an over?ow trunk, means respon
incoming to said o?ice, trunks outgoing from said CH sive to a recall over said incoming trunk if said
o?ice arranged in groups in accordance with o?‘ice
codes, each group including an over?ow trunk
individual thereto, control ‘equipment, means re
sponsive to a call over one of said incoming trunks
for connecting control equipment with said trunk, 10
means in said control equipment for registering
an o?ice code, means in said control equipment
over?ow indicating means is operated'to recon-7
nect control equipment with said trunk, and
means in said over?ow trunk for transmitting the
code of the trunk group to said reconnected con
trol equipment.
-
~_
7
~
'
,5. In a telephonesystem," a toll ,o?lce, trunks
incoming to said o?lce, trunks outgoing from said
office arranged in groups in accordance with o?ice
responsive to the registration of a code ior ex
tending said incoming trunk to an idle one of the
codes, each group including an over?ow trunk in
corresponding group of outgoing trunks or to the
dividual thereto, control equipment, means re
over?ow trunk individual thereto and thereupon
sponsive ‘to a call over one ‘ of said incoming
releasing from said'incoming trunk, means re
trunks for connecting control equipment with said
sponsive to a recall over said incoming trunk to
trunk, means in said control equipment for reg
reconnect control equipment with said trunk and
istering an o?ice code, means normally effective
means in said over?ow trunk for transmitting the 20 to connect said registering means to theincoming
code of the trunk group to said reconnected con
end of said trunk, means in said control equip
trol equipment.
>
,
ment responsive tothe registration of a code over
2. In a telephone system, a toll of?ce, trunks
the incoming end of said trunk for extending
incoming to said o?ice, trunks outgoing from said
said incoming trunk to an idle one of the cor
o?ice arranged in groups in accordance with o?ice
responding group of outgoing trunks or to the
codes, each group including an over?ow trunk
over?ow trunk individual thereto and thereupon
individual thereto, control equipment, means re
releasingfrom said incoming trunk, means re
sponsive to a call over one of said incoming trunks
sponsive to a recall over said incoming trunk .to
for connecting control equipment with said trunk,
reconnect control equipment with said trunk,
means in said control equipment for registering V30 means responsive to said reconnection to connect
an o?ice code, means in said control equipment
said registering means to the outgoing end of said
responsive to the registration of a code for ex
trunk, and means in said over?ow trunk for
tending said incoming trunk to an idle one of the
transmitting the code of the trunk group to said
corresponding group of outgoing trunks or to the
reconnected control equipment.
over?ow trunk individual thereto and thereupon
6. In a telephone system, a toll o?ice, trunks
releasing from said incoming-trunk, means re
incoming to said of?ce, trunks outgoing ' from
sponsive to a recall over said incoming trunk to
said o?ice arranged in groups in accordance with
reconnect control equipment with said trunk and
o?ice codes, each group including an over?ow
means in said over?ow trunk responsive to said
trunk individual thereto, control equipment,
reconnection for transmitting the code of the 40 means responsive to a call over one of said in
trunkigroup to saidreconnected control equip
ment;v
-
‘
-
3. In a telephone system, a toll o?ice, trunks
incoming to‘ said o?‘ice, trunks outgoing from said
office arranged in groups in accordance with oi?ce
codes, each group including an over?ow trunk
individual thereto, control equipment, means re
sponsive to a call over one of said incoming trunks
for connecting control equipment with said trunk,
means in said control equipment for registering
an‘of?ce code, means in said control equipment
responsive to the registration of a code for ex
tending said incoming trunk to an idle one of the
corresponding group of outgoing trunks or to the
over?ow trunk individual thereto and thereupon
releasing from said incoming trunk, over?ow in
dicating means operated in said trunk prior to the
release of said control equipment if said trunk is
coming trunks for connecting control equipment
with said trunk, means-in said control equipment
for registering anoiiice code, means normally ef
fective to connect said registering means to the
incoming end of said‘trunk, means in said control
equipment responsive to the registration of a code
over the incoming end of said trunk for extend
ing said incoming trunk to anidle one of the
corresponding group of outgoing trunks or to the
over?ow trunk individual thereto and thereupon
releasing from said incoming trunk, over?ow in
dicating means operated in said trunk prior to the
release of said control equipment if said trunk is
connected to an over?ow trunk, means responsive
to a recall over said incoming trunk if‘ said over—
?ow indicating means is operated to reconnect
control equipment with said trunk, means respon
sive to said reconnection to connect said register
connected to an over?ow trunk, and means re
ing means to the outgoing end of said trunk, and
sponsive to a recall over said incoming trunk if 60
means in said overflow trunk for transmitting ‘the
said over?ow indicating means is operated to re
connect control equipment with said trunk.
4. In a telephone system, a toll o?ice, trunks
incoming to said o?ice, trunks outgoing from said
o?ice arranged in groups in accordance with o?‘ice
codes, each group including an over?ow trunk
individual thereto, control equipment, means re
sponsive to a call over one of said incoming trunks
for connecting control equipment with said trunk,
code of the trunk group to said reconnected con
trol equipment.
7. In a telephone system, a toll ot?ce, trunks
incoming to said o?ice, trunks outgoing from
said o?ice, said outgoing trunks arranged in
groups, an over?ow trunk individual to each
group, means effective when all of a group of out
going trunks are busy to connect a plurality of
means in said control equipment'ior registering
incoming trunks to the over?ow trunks individual
an of?ce code, means in said control equipment
responsive to the registration of a code for ex
mit an over?ow signal over said over?ow trunk
tending said incoming trunk to an idle one of the
Corresponding group of outgoing trunks or to the
over?ow trunk individual thereto and thereupon
to said group of outgoing trunks, means to trans
to said plurality of incoming trunks,. means re
sponsive to one of said group of outgoing trunks
becoming idle to transmit a reorder signal .over
said over?ow trunk to said plurality of incom~
2,408,432
ing trunks, means responsive to" a recall over one‘
of said incoming trunks to transmit an identi?
cation of said group of outgoing trunks to said
one incoming trunk and means simultaneously
effective to again transmit an over?ow signal to
the others of said plurality of incoming trunks.
8. In a telephone system, a toll office, trunks
incoming to said o?ice, trunks outgoing from said
o?ice, said outgoing trunks arranged in groups,
10
equipment responsive to the registration of a
code for extending said incoming trunk to the
corresponding over?ow trunk if all of the out
going trunks are busy and thereupon releasing
from said incoming trunk, means to connect a
plurality of other incoming trunks to said over
?ow trunk, means to transmit a ?ashing over?ow
signal over said over?ow trunk to all of said in
1 coming trunks, means responsive to one of said
an over?ow trunk individual to each group, means 10 group of outgoing trunks becoming idle for trans
mitting a reorder signal over said over?ow
effective when all of a group of outgoing trunks
trunk to all of said incoming trunks, means re
are busy to connect a plurality of incoming
sponsive to a recall over one of said incoming
. trunks to the over?ow trunk individual to said
trunks to'reconnect control equipment with said
group of outgoing trunks, means to transmit an
one trunk, code generating means individual to
over?ow signal over said over?ow trunk to said‘ I
said over?ow trunk, means under the control of
plurality of incoming trunks, means responsive to
said control equipment to connect said code gen
one of said group of outgoing trunks becoming
erating means with said one incoming trunk to
idle to transmit a reorder signal over said over
transmit the code of the outgoing trunk group
to said reconnected control equipment and means
responsive to said code generator connecting
means to again transmit said ?ashing over?ow
signal to said other incoming trunks.
11. In a telephone system, a toll of?ce, trunks
over?ow signal to the others of said plurality of
incoming
to said office, trunks outgoing from said
25
trunks during the transmission of said identi?ca
of?ce arranged in groups in accordance with
tion to said one trunk.
o?ice codes, each group including an over?ow
9. In a telephone system, a toll o?ice, trunks
trunk individual thereto, control equipment,
incoming to said o?ice, trunks outgoing from
means responsive to a call over one of said in
said o?ice, said outgoing trunks arranged in
groups, an over?ow trunk individual to each 30 coming trunks for connecting control equipment
with said trunk, means in said control equipment
group, means e?ective when all of a group of out
for
registering an office code, means in said con
going trunks are busy to connect a plurality of
trol equipment responsive to the registration of a
incoming trunks to the over?ow trunk individual
code for extending said incoming trunk to the
to said group of outgoing trunks, means to transmit an over?ow signal over said over?ow trunk 35 corresponding over?ow trunk if all of the out
going trunks are busy and thereupon releasing
to said plurality of incoming trunks, code gen
from said incoming trunk, means to connect a
erating‘means individual to said over?ow trunk,
plurality of other incoming trunks to said over
means responsive to one of said group of out
?ow trunk to said plurality of incoming trunks,
means responsive to a recallover one of said in
coming trunks .to transmit an identi?cation of
said group of outgoing trunks to said one incoming
trunk, and means to automatically transmit an
going trunks becoming idle to transmit a re
?ow trunk, means to transmit a ?ashing over
trunks for connecting control equipment with
said trunk, means in said control equipment for
registering an'o?ice code, means in said control
means.
order signal over said over?ow trunk to said plu 40 ?ow signal over said over?ow trunk to all of said
incoming trunks, means responsive to one of said
rality of incoming trunks, means responsive to a
group of outgoing trunks'becoming idle for trans
recall over one of said incoming trunks to con
mitting
a reorder signal over said over?ow
nect said code generating means with said one
trunk to all of said incoming trunks, means re
incoming trunk to transmit an identi?cation of
said group of outgoing trunks to said one incom 45 sponsive to a recall over one of said incoming
trunks to reconnect control equipment with said
ing trunk, and means under the’ control of said
one trunk, code generating means individual to
connecting means to automatically transmit an
said over?ow trunk, means under the control of
over?ow signal to the others of said plurality of
said control equipment to connect said code gen
trunks during the transmission of said identi?ca
50 erating means with said one incoming trunk to
tion to said one trunk.
'
transmit the code of the outgoing trunk group to
'10. In a telephone system, a toll o?ice, trunks
said reconnected control equipment and means
incoming to said o?ice, trunks outgoing from said
office arranged in groups in accordance with o?ice , responsive to said code generator connecting
means to automatically transmit said ?ashing
codes, each group including an over?ow trunk
individual thereto, control equipment, means re 55 over?ow signal to said other incoming trunks
during the operation of said code generating
sponsive to a call over one of said incoming
MARTIN E. MALONEY.
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