Non-completion of internal selection

In the case of non-completion because of internal occupation,
the register, after a period of approximately 5 seconds, uses
the recording device, then makes a new attempt at. selection,

for which all the selection operations are repeated from the

start.

If the same thing occurs again, the call is sent back busy
without using the recording device.

Non-reception of end of selection signal

If the end of selection signal is not received within a period
of 2 to 4 minutes (set by cams) after transmission of the last
digit, the decimal auxiliary gives the "busy" signal to the
register; the MF SOCOTEL auxiliary gives the "congestion"
signal.

[Tr Note: Most of page 95 illegible7

5.2325. Internal selection
Cf. Originating register

5.2326. Outgoing selections
Cf. Originating register

5.2327. End of selection

The originating circuit is operated in decimal code.
Whatever the code used on the incoming circuit, the end of
selection signal is received by the decimal auxiliary and the
communication is routed on an automatic long-distance circuit
or by the originating junctor if the communication is routed
on an auxiliary line or junction to the CT2. It is retransmit-
ted to the originating register by the originating junctor or
by the auxiliary. ~
If the incoming circuit is operated in decimal code, the end of
selection signal relayed by the incoming junctor is retransmit-

ted by the register to the incoming circuit, after which the
register and the auxiliary are disconnected.

16



CHAPTER 6: THE INTERNATIONAL CENTER
6.1. Definitions
6.11. International Center.

An international center is a center placed at one end of an
international telephone circuit.

International centers must be considered:

a. From the point of view of switching facilities:
automatic international center, or manual international
center. .

b. From the point of view of routing on the French network:

general traffic international center, limited traffic
international center, vicinity international center.

6.12. CIA /Kutomatic International Center/

This is an international center with an automatic switcher
which provides:

a. For originating traffic: access to international origina-
ting circuit: which is the head of the line and to a
circuit of specialized beams which provides a link with
other automatic international centers of the French
network.

b. For incoming traffic: routing of all traffic coming from
peams of international circuits for which it is the head
of the line and from specialized beams coming from other
French automatic international centers and local inter-
national originating links.

6.13. CIM /Manual International Center7

When the intervention of an operator is required (operation of
manual circuits, special communications, semi-automatic opera-
tion), a manual international center is associated with the auto-
matic center.

For originating traffic, the operator has access to automatic
international-ecireuits for which the international center con-
sidered is the head of the line, and also to automatic inter-
national circuits accessible from a distant international center
of the French network which can be reached by a beam of special-
ized circuits.

37



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33

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4]

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> PoWO

ts

In the preceding table, the following abbreviations were used:

open circuit

closed circuit on strong resistance

closed circuit on weak resistance

+ on wire a

- on wire b through resistances (relay windings)
- on wire a

+ on wire b

+48 // ab: potential of +48 V in a parallel arrangement

on wires a and b.

The resistance per wire between origination and incoming must
be kept less than 1,200 & and the insulation resistance between
wires, including ground losses, above 50,000 a.

Disconnection conditions

During release of the originating junctor, the circuit remains
open for at least 50 ms.

The "B" loop may appear as soon as this period has elapsed.

The incoming junctor must be disconnected at the latest 300 ms
after opening of the loop.

7679

A new connection loop, b, must not appear in the originating
junctor before a period of 500 ms has elapsed after the start of
opening of the circuit.

CsoO: 8319/0065 - END -

88


Figure 11: The four-wire international circuit-national circuit
transit lets the 0.2 N lines remain in the national circuit and
introduces’a 0.2 N line in the CT4-CI intermediate junctor in
addition to the 0.02 N'line to compensate for the 0.2 N line of
the international circuit which remains cleared. . The attenua-
tion of the national part of the international link shown in
figure 11 is given by the relation given previously.

In the case of the figure, n = 1 and the attenuation is 0.30 N.

For international transit (figure 12), the two 0.2 N attenua-
tion lines associated with each international junctor are
inserted in the link.

Note: In principle (and except for a situation justified by
especially heavy vicinity or international traffic), only some
CTR will be international centers... The other CTR and large CT
and group centers which have to pass vicinity traffic will have
local originating international links. “The other CT and CG
will have international access links.

6.23. International number
This is the set of numbers that a subscriber must dial, after
the international prefix (in France, this is 19) to reach a
subscriber in another country.
The international number includes, in this order:

a. The international indicator of the country being

called;
b. The local.number + area code being called.

The total number of digits in the international number can
not be greater than 12.

qhe yatemational indicator may have one, two, or three digits:
» 12, 13.

The local number + area code (N1...Nn) is the set of numbers

needed to make the selection of a subscriber called from a
long-distance center in his own country.

42



5.2133. Incoming. junctors of the associated international
center. (8/5 intermediate junctor) (line H of table).

The role of these junctors is to provide a link between the
switching line of the international center which is an eight-wire
line and the CT+, which is a five-wire line.
5.22. Conversation Line.
The conversation line of the CT+ is a 5-wire line. Four wires
are used for the two conversation channels, and by appropriation,
for transmission of. supervision. The fifth wire is the test
wire used for maintenance of selectors and for identification.
5.23. Registers.
Two types of registers are or may be used in the CT4:

a. Originating register
b. Incoming and transit register

5.231. Outgoing (or originating) register
5.2311. General remarks

This register handles the communications shown on lines A, E,
F, and G of tHe table.

These communications are then routed to regional or national
long-distance circuits, or to local circuits (lines a and b
of table).

The incoming junctions may be operated either in a decimal
code or in the MF SOCOTEL code.

For routing all communications, the originating register
operates in tandem, no matter what the nature of the incoming
junction (decimal or MF SOCOTEL code). ‘This arrangement enables
all routing information to be centralized at the CT+. The
urban or. suburban center handles unauthorized routings re-
quested by limited service subscribers.

This register may control charging on some junctions.

If the need should arise, it may control overload traffic.

10



A2.123. Signal tolerances

The duration of the transmission constituting the connection
signal must be kept to within + 10 percent. The duration of
transmission of the numbering signal must. be kept to within

* 10 percent; the duration of the disconnect signal must be kept
between 500 and 750 ms.

The duration of the signals received (request to transmit, end
of selection, response, hang-up) may vary by + 20 percent around
the values indicated, including the interval between the two
"end of selection - ringing" pulses.

A2.2. Incoming Communications

The signals exchanged on the circuit satisfy the conditions
stated in Annex II. In particular, the conditions indicated for
the termination of the circuit during all phases of the origi-
nating communication are applicable to the incoming. communica-
tion.

A2.21. The various signals transmitted are the following:
A2.211. Request to transmit signal; duration: 100 ms.

As soon as the circuit is taken, the originating center transmits
a connection signal lasting 100 ms on this circuit.

As soon as the mechanisms of the incoming center are in a suitable
position to receive and handle the request from the originating
center, the request to transmit signal is sent to the originating
center. The interval between the end of the connection signal

and the start of transmission of the request to transmit signal
must in all cases be greater than 150 ms. ‘The originating center
then transmits numbering signals which, depending on the parti-
cular case, consist of 2, 3, 4, 6, 7, 9, or 10 series of pulses,
according to the following possibilities:

A2.212. Numbering signals

a. Two and three-digit numbering signals beginning with the
digit 1.

In principle, these are used to reach special services handled
by the internal automatic switcher (if there is one). However,
some originating centers (considered part of the group) will have
access to special services made available to subscribers of the
incoming center.

70



Originating traffic going abroad coming from another international
center of the French network is, therefore, not included in
traffic statements in the international line center.

To learn the traffic sent in a given direction (for example,
each charge zone of Italy), the traffic statements for this
charge zone made in all international centers and in all local
international links of the French network must be added up.

International incoming or transit traffic is not included
in traffic statements for establishing international accounts.

52



y

Depending on their destination, calls are routed on the beam of
circuits giving access to the general traffic automatic inter-
national center for the direction considered (figure 7). The
call. thus never goes through two international centers, as may
happen with some comminications discussed in paragraph 5.12.
The circuits are operated in international code.

CTR

cu aly F.sp Cet |
F.sp

CTU CIM

YL

Figure 7.

6.422. Communications originating from totally or partially

automated groups whose regional transit center
has a local international link.

The group center is equipped with an international access link.

It has a beam of direct circuits with the local international
link.

Communications are charged by the local international link and
charge pulses are retransmitted on an appropriate transmission
channel (figure 8)

CTR
(CLI), / F.sp CIA Cet |

cc f_\ F.sp
(ch Al) ne a, CIM
F.sp .
we a Fig 8
Figure 8.

If the traffic and distance do not warrant a beam of circuits
between the CG and the CTR, communications may be routed by a
transit center, if this transit center has a CLI (figure 9).

50



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56



Comments:

1. In the case of SRCT or Pentaconta sector center the
subscriber hears the maneuver tone transmitted by the

connection center.

2. In the case of SOCOTEL Sl sector center, the maneuver
tone is transmitted by the sector center after reception
of the electrical request to transmit signal.

b. Pulse code (50 Hz alternating current)

Phase

Caller hangs_up

Connection . -——> 100 ms

Request. to transmit < 100 ms

Numbering. > AES OF

Ringing. — —-Return_call

Busy _ ee <—1s

Charging _ _ < < 125/125
——» 500 ms

Disconnect

~—— Above 1 s

60



Only centers handling transit between another group center
(equipped with an access link) and an international center whose
amount of international traffic and whose geographic position
justify it are equipped with a CLI. .

Communications are routed to. the CIA by a specialized beam. They
are charged by the local international link.

If the communication is entirely automatic and is destined

for a country accessible directly from the CIA, the call is
routed on the appropriate beam for the direction requested with
or without the possibility of overload, depending on whether

it is a transversal beam or a normal beam. If the communication
is to be established through an associated manual international
center, the call is routed to this center (figure 3).

Cet I
CIAT
ce
(CLI) O-

Figure 3.

If the communication is entirely automatic and is destined for

a country accessible from another automatic international center
(for general traffic) either in normal channels, or in overload,
the call is routed from the first head of the line international
center (beam operated in an international code). (figure 4+).

48



Originating junctors to CT2 (column j of table).

The auxiliary lines associated with these junctors are two-
wire lines.

The maximum resistance per wire between dispatchers must not
exceed 500:ohms per wire.

Originating junctor to associated international center.

These junctors are used to adapt internal signaling of the
four-wire transit center (done with five wires) with the signal-
ing used by the international center (eight wires).

Category of Originating Junctors

These categories are indicated in 5.2315 (internal selection).
They are used to set the program for later operations. Ina
given beam, some circuits may be operated in decimal code, others
in multifrequency code.

5.25. Monitoring of the Automatic System
5.251. Lamps indicating occupation of common mechanisms.

Two lamps indicating occupation are provided for the following
common mechanisms, one on the supervision band, the other on
the automatic system monitoring panel.

markers

marking channels (one occupation lamp per channel)
translator

register (the lamp flickers at the 500/500 rate before
receiving the first digit, and burns steadily afterwards )
receiver

sender

The ignition of the occupation lamps of the monitoring panel is
controled by one ignition button per group of 20 lamps.

5.252. Lamps associated with junctors
Automatic long-distance incoming junctors

One individual lamp is on the rack-monitoring band. This lamp

signals that the disconnect signal did not arrive when the incoming

register is disconnected, either because the lines of the beam
called were busy, or because the release cams caused the
register to disconnect.

20



For incoming traffic, the operators answer code 11 and code 12
calls arid calls for assistance coming in on beams for which
the associated CIA is the international head of the line.

Operators of the manual international center also handle manual
international circuits for which this center is the international
head of the line.

In this document, we will use the term "international operator"
to mean an operator who handles an international circuit;
"national operator" will refer to all other operators of the
French network.

6.14. International center for general traffic

An international center is called a general traffic center for
a given direction when the beam of circuits it handles in this
direction is-a:beam.of normal circuits (beam of circuits with
low loss probability) or, in the case of a beam of transversal
circuits, when an overload can only be handled by a foreign
international center.

6.15. International center for limited traffic

An international center is called a limited traffic center for
a given direction when the beam of circuits it handles in this
direction is a beam of transversal circuits (beams of high
efficiency circuits with the possibility of overload on another
French international center).

6.16. International vicinity center

An international center is called a vicinity center for a given
direction when the beam of circuits it handles in this direction
routes only traffic for the vicinity.

A single international center may, therefore, depending on the
international relation being considered, be a general traffic
center, a limited traffic center, or a vicinity center. For
example, Lyon is argeneral traffic international center in

its relations with Germany, and a limited traffic international
center in its relations with Belgium. Nice is a vicinity inter-
national center for the Nice-San Remo link and a limited traffic
international center for the Nice-Milan relation.

6.17. CLI /Gocal International Originating Link7

This is a link which enables the automatic subscriber of a
non-CIA transit center --. and even more so, the subscriber of

a CTR -- and of local group centers of this center to obtain
through an automatic international center an international
originating communication according to the methods of operation
described in 3.2. 38



A2.122. Case of originating communication with regional
automatic service

When a circuit of the beam selected is taken, signals meeting
the description given previously for the national long-distance
service (except in the part concerning the number of series of
numbering pulses) are exchanged on this circuit with the center
served by this circuit.

The number of series of pulses transmitted after selection of
the circuit may vary between 1 and 9. If the number of pulses
transmitted is only 1, 2, 3, or 4, these series are identical
to the last 1, 2, 3, or 4 series of pulses received.

If the number of series of pulses is over 4+, the last four

series are identical to the last four series received; the number
and type of the first series are determined by the combination
of one, two, three, four, or five digits which was used to
designate the beam of outgoing circuits.

The first series transmitted must be able to be formed as
indicated below:

1. Q, PQ, BQP (series received);
2. P', Q' are substituted for the PQ received;

C. ABPQ (AB is the departmental indicator of the department
of the person called). This combination must be preceded
by_a preliminary series of 12 or 13 pulses.

To permit the possible use of auxiliary channels, it must be
possible to command, in case of congestion of the beam of cir-
cuits toward the direction considered, an overload to a pre-
determined transit center.

In this case the number and type of the series of pulses re-
transmitted on auxiliary channels will be:

a. six or seven series received, preceded by an additional
series of 11 pulses if the transit center is in the same
regional numbering zone as the subscriber called;

b. eight series preceded by an additional series of 13 pulses

if the transit center can only reach the subscriber called
in the national numbering system.

69



CHAPTER 5: THE FRENCH NATIONAL FOUR-WIRE SWITCHING TRANSIT
CENTER

[Text] This type of center has an automatic switcher system
using four-wire connections and switching, junction circuits,
local (automatic) circuits, automatic and semi-automatic long-
distance circuits, and possibly junctions with an automatic
international center.

The four-wire automatic switcher may be used either in a CTR
[Regional Transit Center] or in an ordinary CT [Transit Center].

The various links made possible by the four-wire automatic
switcher are indicated in the following table.

The lower-case reference letters on this table give special
features of routing and have the following meanings:

a. Communications sent to CG [Group Centers] received by an
entirely automatic channel, either with a regional or a
national numbering system.

b. Only communications sent to CG accessible only from the
Group Center are routed via the CT4.

ec. Calls that require the intervention of a distant operator
are sent by using either of these formulas: PQ 9111, or
ABPQ 91-11.

d. Only communications destined for local centers accessible
only from the local center are sent via the CT4.

e. The CG called are reached either directly by the CT4, or
in transit via the CT2 (French national two-wire transit
switching center).

f. The local center calling served by an automatic switcher
of the intermediate center type may call directly by the
cT2 any CG served by the CT2.

1



1.  one-character prefix consisting of a series of 12
pulses; this prefix means that the number to follow
is a complete national number of eight characters and
that an auxiliary channel may possibly be used in case
of “congestion on the normal channel.

2. one-character prefix consisting of a series of 13 pulses;
this prefix means that the number to follow is a complete
national number with eight characters but that a diver-
sion has already been made, and no additional auxiliary
channel is to be used.

3. two-character prefix. This prefix consists of one pulse
followed by a series of six pulses. It has the same mean-
ing as the series of 12 pulses.

Reception of these signals prepares for the connection by auto-
matic mechanisms between the incoming long-distance circuit and
the line of the subscriber called or the circuit used in transit.

In the case of transit:

Upon reception of a preliminary series of 12 pulses on the
incoming circuit:

a. a preliminary series of 12 pulses will be transmitted on the
originating circuit if this circuit belongs to the normal channel;

b. a preliminary series of 13 pulses will be transmitted on the
originating circuit if this circuit belongs to the auxiliary
channel.

Upon reception of a preliminary series of 13 pulses on the incoming
eircuit, a preliminary series of 13 pulses will be retransmitted
on the originating circuit, which means that the overload indica-
tor must be kept until reaching the incoming center.

Depending on the nature of the sigrials, the communication will be
an incoming, regional transit, or a national transit communication.

If it is a transit communication, these signals are used to take
an originating automatic long-distance circuit in the same con-
ditions as those required for routing a call from a local sub-
scriber to a long-distance originating circuit and to verify,

if need be, that there is compatibility between the AB and the
PQ received in the last transit center.

72



The allocation of any incoming circuit equipment must in any
event create no problems. .

Db. Numbering signals with 2 or 4 characters in format. 10 or AB1Q.

These numbering signals are allocated to the incoming semi-auto-
matic long-distance service for calls between operators; sub-
seribers can not call operators with 2 or 4 digits (this impos-
sibility is built into the system from the starting point).

These signals may be of the 2-character type: 1Q,Q which may
take the values:

8: national operator
7: international operator
3: information operator or of the 4-character type: AB1Q

AB is the departmental prefix and Q has the meanings given earlier.
Cc. Four-digit numbering signals beginning with 10,11, or 12.

In principle, these are used to reach long-distance tables by the
internal automatic switcher (if it exists). The originating center
mentioned earlier in a, considered to be part of the group, will
not have this capability.

d. Six or seven-digit numbering signals.

These are used to reach subscribers of the center, subscribers
of automatic group networks, and subscribers of automatic networks
included in the 6 or 7-character regional numbering zone.

e. Numbering signals with 7/8 characters.

These are formed of numbers with six or seven characters preceded
by a prefix consisting of a series of 11 pulses meaning that the

number to follow is a complete regional number with six or seven

characters, but that as a diversion has already been made, no ad-
ditional or supplemental channel is to be used.

f. Numbering signals with nine and ten characters.
These are used to reach automatic networks accessible by the
automatic long-distance service coming from a great distance,

using eight-character numbers preceded by a prefix of one or
two characters with the following meanings:

71



a

Upon the response of the person called, the "response" signal
is ‘sent on the long-distance circuit to the originating center.

This signal consists of a pulse lasting 100 ms transmitted at
least 100 ms after cessation of the’ end of selection signals,
if there are any. a .

A2.216.  Hang-up signal

This signal consists of a series of pulses, each lasting 100 ms,
separated by intervals of 233 ms, wminterrupted until discon-
nection or until the telephone receiver of the person called is
picked up again.

A2.217. Disconnect signal

Whatever the phase of the communication, whether completely
established or not at the time when this signal is received,
the "disconnect" signal consisting of a single transmission
lasting more than 500 ms causes the disconnection of the auto-
matic links.

A2.22,. Duration of pulses

The durations of transmissions forming the request to transmit,
end of selection, response, and hang-up signals must be kept to
within + 10 percent.

The rate of sending of 100-ms pulses spaced by 250 ms used for
hang-up signals of the person called or possibly for busy signals
must correspond to 100 pulses in 35 s, within + 10 percent.

The incoming equipment must operate within the following limits
for signals received:

a. Connection signal: 70 to 130 ms
b. Numbering signals

Numbering pulse reception and recording devices must operate
correctly under the following conditions:

1. With pulses whose speed of transmission may be between
8 and 12 pulses per second, that is, whose total duration
(active part + interval) may vary between 125 and 83 ms;

2. With pulses whose active part may have a minimum duration
of 30 ms, the interval between the successive pulses is
the complement of the total duration of a pulse defined by
the two extreme speeds listed above;

74



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At the present time, if the incoming circuit is operated in
multifrequency code, this signal is retransmitted to the
multifrequency receiver which transmits the status of the
number called, "subscriber called free with charge" or
"subscriber called busy" to the incoming circuit. After this, I
The register, the auxiliary,’and the receiver are disconnected. |
Later the end of. selection siganl "subscriber free with charge" |
may be sent systematically on the incoming circuit (MF SOCOTEL)
as soon as the last digit is received. The busy signal may
then be given by sending a tone.

The originating circuit is operated in multifrequency code.

If the incoming circuit is operated in decimal code, the

Status of the number called code (multifrequeney code) is re-
ceived by the multifrequency auxiliary which retransmits it to
the register. The end of selection signal "subscriber free"
or "subscriber busy," relayed by the incoming junctor is re-
transmitted by the register in the incoming circuit; after this
the register and the auxiliary are disconnected.

If the incoming circuit is operated in multifrequency code,
the register and the multifrequency register are disconnected
after the last internal selection. Before this, the receiver
sends the multifrequency "transit" signal or possibly "con-
gestion" on the incoming circuit.

5.2328. Incidents
Non-reception of request to transmit signal
Automatic long-distance operation

If the request to transmit signal is not received within a
period of time fixed by the timing device (10 s cams on the
decimal tty) delayed relay of about 5 s on the multifre-
quency auxiliary), the register so informs the originating
junctor, which passes to a "half-fault" status, may possibly
use the observation device (order to call or not by special
loeator button) and makes a new attempt at selection, for which
all the operations are repeated from the start.

If the same phenomenon occurs on the second attempt, the origi-

nating junctor receives the "half-fault" signal and the register
sends back the call as busy without observation.

Operation of Auxiliary Lines

Functioning is similar to that described above, but there is
no passage to "half-fault."

17



5.271. Traffic observation by conventional equipment
5.2711. Counters

See paragraph 5.26.
5.2712. Traffic analyzer.

This device may be branched either on incoming junctors (of any
type) or on outgoing junctors (of any type).

Ten junctors may simultaneously be connected to the device,
but only one communication may be observed at one time. When
the device is free, it is connected with the first junctor on
which a call appears.

The link between the ten observation lines of the device and
the junctor observed is made by a jumping wire to the inter-
mediate dispatchers.

Observations on incoming junctors
For each call the analyzer registers:

A. The time that elapses between sending of the request to
transmit signal by the register and the disconnecting of
the register. The time represents "dialing + selection."

B. If the end of selection "subscriber called free" signal
is received, the time elapsing between the release of
the register and the response of the person called. This
time is the "response time."

Cc. When the subscriber answers, the time elapsing between
reception of the response signal and hanging. up by one
of the two parties (disconnect signal or hangup signal
of the subscriber called). This time is the "length of
conversation."

In the case of call back (commmication established by an
operator) the conversation time after the new response is
added to the preceding time and only one call is counted.
Times A, B, and C are: recorded on time totalizers.
Moreover, the analysis also totals separately:

D. The number of "actual calls" (calls resulting ina
charged conversation).

23



Each translator must have ten keys which can, without any

change in wiring, modify the path to which each key is assigned.
This modification may be made, if desired, based on the category
of the incoming junctor. The operation of each key is signaled
py the lighting of a’ lamp.”

5.24. Originating Junctors

Originating junctors using decimal code signaling to automatic
urban and suburban switchers (column d of table).

The auxiliary lines associated with these junctors are two-
wire lines.

The maximum resistance per wire between dispatchers must not
exceed 500 ohms per wire.

Originating junctors to urban and suburban automatic switchers
using an MF SOCOTED code (column d of table).

The auxiliary lines associated with these juncters are two-
wire lines.

The maximum resistance per wire between dispatchers must not
exceed 1,100 Q.

Originating junctors to local group centers attached to CT4
(column b of table).

Originating junctors of automatic long-distance circuits
(colum a of table).

The same junctor can be used on circuits operated in both
automatic long-distance code with decimal numbering and in MF
SOCOTEL code. Straps are used to adapt the junctor to the code
being used.

Links between the CT4 and the transmission station require
seven wires:

two wires for sending

two wires for return

two signaling wires (TRON and RON)
one blocking wire

The maximum resistance per wire between the dispatcher of the
station and the CT+ dispatcher must not exceed 300 ohms.

19



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32



Upon reception of a regional number, the following may
be sent back:

PQMCDU
or QMCDU
or MCDU
or DU
or U

After the last internal selection, the register takes the
auxiliary and communicates to it:

Possibly the indication of the series of 10 pulses to be
sent;

The number of digits of the number received to be sent.

When the auxiliary is taken, and if there are translated digits
to be sent back, the register uses the translator. The trans-
lator communicates to the auxiliary in a unit the translated
digits to be sent; there may be 1, 2, or 3 digits. This arrange-
ment makes it possible to send back a national number upon
reception of a regional number.

The digits of the number received which are to be sent may be
transmitted one by one by the register to the auxiliary; the
transmission of one digit is done during transmission of the
preceding digit.

Auxiliary Multifrequency Code

The operations take place according to the procedure established
by the SOCOTEL multifrequency code.

d. End of selection

The end of selection signal (decimal code) or the status of
number called (multifrequency code) is received by the auxiliary
(decimal or MF) and is retransmitted immediately to the register.

IF the subscriber called is busy, the register is disconnected
after releasing the originating line.

If the subscriber called is free, the register notifies the

originating junctor to enable it to receive the response signal,
then it disconnects.

In case of reception of a busy signal (MF SOCOTEL code) it is
possible, using a variable connection, to resort to one of the
following two procedures:

14



b. Direct current pulses - 48 V on the two line wires
Ce or ground pulses on a TRON control wire

The signals received are of the same type and consist of:

a. Pulses of 50 Hz alternating current (voltage above 20 V
at the limits of 600 Q - 2uF)

b. Direct current pulses - 48 V on the two line wires

Ce Or ground pulses on a RON control wire

In'all these cases, the resistance of the RON wire (including
reception relay) must be above 1,000 a. Protection will be
provided by a varistor or by an equivalent device.

While the conversation link is not established, the circuit
will be closed at each end on an impedance of 600 2 (possibly
in a serial arrangement with a capacity of 1uF).

The circuit will be separated from the office side 30 to 50 ms
before the start of transmission of a signal, and will only be
connected 30 to 50 ms after the end of this transmission.

The incoming equipment must function within the following limi-
tations for the duration of signals received, expressed in
milliseconds:

a. Connection, response, call back signals: 80-220
b. Hang-up signal: 100/400
Cc. End signal: minimum duration 500

A parasitic transmission lasting less than 35 ms will not be
interpreted as a signal.

A signal lasting longer than 500 ms must not be able to be
interpreted as the arrival of a connection signal and must not
engage the incoming junctor.

Moreover, the provisions required for the recall signal to be
transmitted in its entirety during the duration of a phase of sil-
ence of the person called's hang-up signal must be made. The
reception of the recall signal will cause, in the incoming equip-
ment, the elimination of the transmission of "alternated pulses."

A3.62. Line signaling; status code (direct current)
86



If it is an incoming communication, these signals are used to
make all the selections needed inside the group, whether the

subscriber called is linked to the main automatic switcher or
is on a local automatic center, which will’ sometimes require

analysis of the first six digits, ABPQMC.

A2.213. End of selection signal - subscriber busy

If the subscriber called is busy, either he has only a single

line, or he has several and all were busy, or if the selection
can not get through for lack of mechanisms available at any
stage of selection, an "end of selection - subscriber busy"
signal is sent on the long-distance circuit to the originating
center.

This signal may consist of:
a. one single pulse lasting 100 ms

b. a series that is uninterrupted until disconnection
of 100 ms pulses, separated by intervals of 233-ms
(case of semi-automatic incoming circuits)

ec. the sending of an audible busy tone to the originating
center.

A modification of connections of a very simple nature will make
it possible to use the appropriate type of signal on each circuit.

A2.214. End of selection signal -- ringing

If the number called is ringing, either the subscriber has only
a single line, or he has several and at least one is free, and
the "end of selection - ringing" signal is sent on the long-
distance circuit to the originating center.

This signal consists of two 100-ms pulses separated by a 100-ms
interval.

However, on semi-automatic long-distance circuits for which the
"end of sélection -' busy" signal consists of an uninterrupted
series of 100-ms pulses separated by 250 ms, no "end of select-
ion - ringing" signal is sent; only the return call tone is sent
to the originating center.

A2.215. Response signal

The call current is.sent on the line of the subscriber called,
when ringing according to the conditions described for establish-
ing a local communication (TL traffic).

73



a. Status code (direct current)

CG cs
cr cs
Phase CG CI
Rest 5002 loop 500 11 loop
Connection Ground on A; 500 {2 loop \

Good circuit

Request to
transmit

Numbering
Ringing
Busy

Call release

Response
requested

Hang-up
requested
Call back

Disconnect

Comments:

battery on B
Power supply
Power supply

Openings of 50/50
power supply

Power supply

Power supply

Opening of
power supply:
200 ms

Power supply
Power supply

Opening of power
supply: 200 ms

Definitive open-
ing of power
supply then weak
loop

12,500 f loop
500 1. loop

500 SL loop

Breaking of loop and
12,5002 loop

+ 48 V on A and B
12,500! loop
50012 loop

12,500 £2 loop

12,500 SL loop

500f2 loop

1. The weak loop at rest in the group center is necessary
only in the case of a mixed circuit (see table Al.3).

2. The busy signal (+ 48 V on A and B) is given for about
200 ms; it is followed by a 12,5002 loop.

58



The appropriate circuits thus formed are used to transmit
signaling.

5.14. Link stability before conversation

In the case of a link between an amplified circuit and an
auxiliary line or a non-amplified circuit, an attenuation line
of 0.4 N will be placed in the two-wire part of the connection
each time that there is a terminator in the office when the
attenuation of the junction is less than 6 decinepers.

This attenuation line will be erased upon reception of the
response signal.

If the attenuation of the junctor is above 6 ds, straps will be
used to permanently eliminate the cell; "switching will become
ineffective when the subscriber called answers."

5.2. Equipment
5.21. Incoming Junctors
5.211. Categories of incoming junctors

Depending on the conditions in which their communications are
to be routed, the incoming junctors are served either by the
originating registers or by incoming registers. The role of
each of these registers is explained later.

In addition to the routing conditions derived from their service
by one or another type of register, each incoming junctor may
be assigned a category stating its conditions of operation,
which enables the traffic observation equipment, whose role is
described later, to analyze the traffic based on its origin.

Category allocation is done on a group of spindles associated
with each incoming junctor.

The categories of incoming junctors now used are the following:

Junctors serviced by originating registers.

Eight categories are specified; the following are those now used:
a. Auxiliary signaling line in use in local networks
b. Auxiliary MF SOCOTEL code line with charge retransmission
ce. Junction from the connection line of the SRCT

automatic switchers to the group with charge retrans-
mission


Rapid and systematic transmission tests.

These tests are only for originating junctors. Their purpose
is to check:

That the exchange of line signals is correct;

That the circuit's transmission qualities are acceptable
for conversation and, in the multifrequency signaling
system, for the exchange of code and numbering signals.

A light indicator placed on the test unit shows at each moment
the number of the junctor to which the unit is connected.

On circuits operated in decimal code, the hypsometer has a
three-digit number (777 or 999). On circuits operated in MF
code, the hypsometer has a four-digit number (7799 or 9989),
preceded by the regional access code, Al.

Manual tests of originating junctors

These tests are to enable the originating switching center to
locate the incidents signaled by the rapid and systematic trans-
mission test device.

Manual tests of incoming junctors

These tests are to check the length of the line signals, trans-
mission levels, and to locate incidents signaled by the origi-
nating center.

Start of service and maintenance of originating circuits o
These operations are done from the originating office on signal-
ing circuits by RON and TRON wires (outside signaler). They
are used for adjustment and control of the circuit signalers.

Distortion tests (decimal numbering only)

These tests are to check the behavior of the retransmission
mechanisms from the point of view of the restoration of the
numbering signal.

These tests may be done:

Either on the originating or incoming junctor;

Or at any point of the circuit with calibrated transmission

at origination: signaler of an intermediate station,

ree ne junctor of a distant center (case of a complete
ink).

29



The impedance of the 50 Hz transmission circuit must be as
close as possible to the impedance of the termination acceptable
for the circuits, taking into account control resistances.

Discharge from the cable will be handled by a pure resistance
of 600 2 and.not by a. short-circuit, as the receiving circuit
is open. The. duration. of discharge will last between 50 and

100 ms; in no case will it exceed 100 ms. i

Reception

The "internal" signaler must have the following characteristics,
especially for incoming use, where it is handling number selec-
tion.

a. On non-synchronous transmission of the last signaler,
the signal must be restored to + 10 ms taking into account
voltage variations.

b. The signaler must function correctly with 200 mVA and must
have a minimum impedance of 2,000 2 approximately at 50
Hz.

Cc. The signaler must have a very high impedance on conversa-
tion currents (10,000 2 at 800 Hz - level 0).

A2.113. Direct current signaling on two line wires

In transmission the direct current supply (-48 V and ground)
must be able to be substituted easily for the 50 Hz power
supply. The control resistances will be kept in the transmis-
sion circuit.

In reception, the 50 Hz signaler must be able to be reused
without modification on direct current pulses.

A2.114. Signaling by TRON and RON wires
The acceptable. intensity on the RON (reception) wire must be
less than 50 mA, no matter what reception equipment is used.
All appropriate precautions must be taken to ensure protection
of the control contacts.

A2.115. Terminations

At rest and during all the preparatory phases of communication,
the circuit must be ended both for outgoing and for incoming
traffic on a 600 2 impedance, no matter what signaling mode is

65



A2.1212. Numbering signals

These consist of a series of pulses transmitted at the rate of
10 pulses. per second;. the ratio between the duration of one

pulse to the duration of the interval between two successive
pulses is equal to 1. The interval between two series of pul-
ses has a minimum duration of 500 ms; the maximum duration of
this interval is set at 1s if the following digit is registered.

The number of series of pulses transmitted may vary between 1
and 9.

The series of pulses transmitted are of the ABIQ type, or are
identical to the last. 1, 2, 3, 4, 5, 6, 7, or 8 series of pulses
received from the calling subscriber (U - DU - CDU - MCDU -
QMCDU - PQMCDU - BPQMCDU - APQMCDU). They may be preceded by

an additional series of pulses, with either 11, 12, or 13 pulses;
the meaning of these pulses is explained later.

The number of series of transmitted pulses is determined by the
combination of characters (A, AB, ABP, ABPQ) which was used to
determine the beam of automatic long-distance circuits used by
the communication.

For some relations normally reached through a CTR or CTD transit
center, eight series of pulses identical to the eight series of
pulses received should be sent back, preceded by a series of 12
pulses characteristic of a national call.

In order to facilitate the possible use of auxiliary channels,

the automatic mechanism must be able to command, in case of con-
gestion of the beam of circuits in the direction considered,

the overload towards a predetermined transit center. In this

case eight series of pulses identical to the eight series of
pulses received are sent back to the transit center in question to
characterize the identity of the subscriber being called.

Moreover, these eight series of pulses are preceded by an addi-
tional series of 13 pulses meaning that an overload has already
taken place. Precautions to be taken in the transit center
used by the auxiliary channel will be given later.

A2.1213. End of selection signals; response and hang-up
signals

As soon as the incoming long-distance center has completed the

selections corresponding to the numbering signals which were
sent it, it transmits an "end of selection" signal.

67



This signal differs, depending on whether the subscriber called
is busy or ringing.

If the subscriber called is ringing, the end of selection signal
consists of two 100-ms pulses separated by a 100-ms interval.

The incoming long-distance center then sends the call current on
the line of the subscriber being called and when he answers, it

sends a "response" signal consisting of one 100-ms pulse, trans-
mitted at least 100 ms after the end of the preceding signals.

When the subscriber called hangs up the phone, the incoming long-
distance center sends an uninterrupted "hang-up" signal consist-
ing of pulses lasting 100 ms, separated by 233-ms intervals.

If the number called is busy, the end of selection signal con-
sists of a single 100-ms pulse.

A2.1214. Disconnect signal -- minimum duration: 500 ms
This signal is transmitted:

a. As soon as the calling subscriber hangs up his receiver,
no matter what the phase of the communication in progress,
unless the connection signal itself was not transmitted;

b. Within a 20 to 40 s period after reception of the signal
indicating that the subscriber called has hung up his
phone. It must be possible to eliminate these special
provisions, needed in some directions, whenever they
are unnecessary;

Cc. Within a 2.5 to 5 s period after reception of the signal
indicating that the subscriber called has hung up his
phone, if the previous arrangements described are not
required.

In the two preceding cases, if the hang-up signal stops before
the disconnect signal is sent, everything proceeds as if the
hang-up signal had not been sent.

d. Upon reception of the signal indicating that the subscriber
called was busy at the end of selection.

e. In case of reception of an inappropriate pulse on the
circuit (switching mechanisms at rest).

Transmission of the disconnect signal is immediately followed by
the complete disconnection of the automatic links.

68



b. The operator was present at the start of observation.
The device which has worked to analyze the number called,
will not handle this call to memorize the information
which could be recorded and will only do a complete ob-
servation of a call coming in after the withdrawal of
the operator.

The number dialed is displayed on an eight-character light
panel.

The type of number called is displayed on lamps (national,
regional, or special services numbers).

If a charger is associated with the incoming jJunctor, the
number of charge pulses for the communication observed is also
displayed on a counter with return to zero.

5.272. Electronic traffic observation
This issue is discussed in paragraph 3.2.

5.273. Maintenance

5.2731. Incidents during selection
When an operation is not accomplished within the scheduled period
of time, a recording device is used which indicates the various
mechanisms involved in the communication and the position of
their major relays.
The use of the recording device is ordered by the mechanism which
observes the non-completion within the prescribed time period.
This mechanism is called the "active mechanism."
The active mechanism calling is sought by the locator. When
the search is completed, the active mechanism places all the
common mechanisms (passive mechanisms) with which it is associated
in a position connected with the recording device.
The data on the identity of the mechanisms (active and passive),
their status, and the conditions requiring fault recording are
recorded in a memory, then transmitted to the recording device.

The same mechanism may, if the occasion requires, either be
an active or a passive mechanism.

5.2732. Test of decimal senders and registers

26



a. Al and A2 signals

Whatever the nature of the call, a single Al signal, "send the
access signal and the first two or four digits," has been desig-
nated. This makes it easy to control the number received in
all instances, as shown in the following table (access signal

+ four digits}. :

Undiverted call Diverted call

National case 3abdpq Habpgq
Paris region 1bpgqm 2bpqm
Provincial region 1P4me 2pqme

The A2 signal, "send the last digits," is used to complete the
number of the person called. The A2 signal not preceded by
the A1 signal means, "send the last four MCDU digits."

The use of these two signals makes it possible to avoid repe-
tition of the complete number of the person called in each transit
center which is involved in establishing the communication.

b. A3 signal (passage to code B)

This signal is transmitted by the incoming register when it knows
the status of the line called.

c. A4 signal (passage to code C)
This signal may be transmitted at any time during the establish-
ment of the communication by the incoming register or transit
register when it is necessary to know the category and number of
the caller.

d. <A5 signal (send the category of the caller).

This signal is used instead of the A4 signal when it is necessary
to know only the category of the caller.

e. A6 signal (normal transit) and A7 signal (diverted
transit)

The register of a transit center transits the A6 signal if it

is routing the communication by a normal channel, and the A7
signal if it is routing the communication by a diverted channel.

78



ROUTING TABLE

Sorties
a a b d e f f A ji
1 QO] x les 3s |e Slee al ge
ra 5 32 BR Bk 25
a /¢ Be bs~|28_G|e2_G|fe8<le 2 ea
B | Bex | eG geen lSssl/Ssel/ssee is 5 Bh
“les | as B850/F822/2822/F 220g 288] G20 | 20
ges | 2 oBg/RSbe/SEes REG 2/5 § 58
ENTREES bee leg p83 /gi Pel ge Pgs 50 z]8 3 S38
= o> e Bs ale a) =e
1 tb | 3 3 5 G 7 8 "

A. — Lignes auxiliaires en pro-| Aa | A.b
venance des centres urbains ct| (a) (b) | (b)
suburbaines pour trafic régional et|  (c)
national automatique.

B. — Ccts en provenance des} Bia B.b Be Bd By
centres locaux automatiques du} (a) (c) | (f) (g) | (h) (i) (k) (e) (g)
groupement (raccordés au C.T.4).| (e) (f)

BORO

C. — Cets arrivée interurbains| Ca | C.b cd | ce | ce | cg | ch Cj
automatiques en provenance des| (a) (c) | (2) @ | @ | @ ©) (@)
C.G. de la zone régionale, ©

(0) (p) _ _ _

D. — Cetsarrivée interurbains| D.a_ | D.b Dd | De | vr | Dg Di
automatiques en provenance des| (a) (c)| (g) (m) (n) (p)

CTR. (©) (h)
_ (6) (p) .

E. — Jonctions en provenance) Ea | E.b
du C.T.2 pour acheminement des| (0) (b) | (4)
appels en provenance des centres| (¢)
locaux automatiques du groupe-
ment pour trafic régional et na-
tional automatique.

F,— Jonctions en provenance) Fa | Fb
du C.T.2 pour acheminement ap-| (0) (q) | (4)
pels en provenance des ccts inter-| (r) (c)
urbains automatiques et des opé-| (I) (0)
rations de linterurbain manuel!  (p)

(LA.C., chaine régionale).

G. Jonctions en provenance} C.a
de l'interurbain manuel (LA.C.,| (a) (b)
chaine nationale). (ORO)

G) ©)
(p)

H. Jonctions en provenance dul H.a H.b Hd
Ci. (a) (e)

|. Lignes auxiliaires en pro-| La
venance centres urbains et sub-| (i) (j)
urbaines pour trafic international. | (s)

J. — Jonetions en provenance] Ja
du C.T.2 pour acheminement ap-| (i) (i)
pels en provenance des centres! (a)

I>caux automatiques du groupe-
ment pour trafic international au-
tomatique.

K, — Lignes d’appel au clavier] Ka | Kb | Kc Kj
des opératrices du centre manuel
associé au C.T.4,



Automatic local centers called are reached either directly
by the CT4 or in transit by the CT2.

Links used when there is a CI [International Center] asso-
ciated with the CT4 for routing calls destined for inter-
national circuits accessible from this CI. Other interna-
tional calls are routed by national circuits to a CI which
is the head of the line via the CT4 associated with this
cI.

Entirely automated connections and those which do not re-
quire the intervention of a foreign operator on the line
are open only to subscribers.

If there is no associated CI, automatic international calls
are routed to a distant CI, using both regional and national
automatic long-distance circuits.

The local center calling served by an automatic switcher
of the intermediate center type may call any urban or
suburban center directly by the CT2.

Calls destined for B operators of a distant transit center.
These calls are made by the operator originating the call
using the number AB18.

Communications for subscribers of the CT4 group operated
manually or in a rural automatic system (calls made by
subscribers or by distant operators using the numbers
PQ 9111 or AB PQ 9111).

These operators are only called by distant operators, who
call a 4-digit number in this form: AB 18. This method

is used to route communications for manual or rural sub-

scribers of the CTR area. Communications towards e and f
may be routed on the same beam upon leaving the CT4.

Calls for international operators in a distant interna-
tional center.

Calls for international operators are made by the local
operators originating the call using the number: AB 17.

Communications for CG accessible either only from the CG,
or from the CT2, and during overloads of the CT2 are
routed by the CT4.

Routing used in originating calls from the CG which do not
have access to CT4 and by CG which have access to CT2 or
to cT4.



Sending back of busy signal;

Attempt to use overload channel (but in this case, the
same call will be indicated twice as "routed" by the
traffic obsservation device.

e. Transmission of Charge indication

After reception of the end of selection signal, the register
uses the translator to give the incoming junction the rate to
be charged for the communication.

The translator may indicate ten different rates, including charge
1 without time limitation.

The reception of the end of selection signal (number called
without charge) does not entail the "transmission of charge
indication" operation.

f. Incidents

Non-reception of request to transmit signal

Automatic Long-Distance Operation
If the request to transmit signal is not received within a
period of time set by a time delay device (10 s cam of the deci-
mal auxiliary, delayed relay about 5 s of the multifrequency
auxiliary), the register so informs the originating junctor,
which passes into "half-fault." It may use the observation
device (order to call or not by special locator button) and
makes a new attempt at selection, for which all the operations
are repeated from their start.

If the same phenomenon occurs during the second attempt, the
originating junctor receives the signal of passage into "half-
fault" and the register sends back the busy signal without
observation.

Incorrect call -- incomplete number
If the number does not get through after connection of the
register within a period of time set by a 10 s timing device,
the register uses the translator to route the call, using the
instructions given (call back. busy, call back on film or call
operator).

Level not used

The call may either be sent back busy, or sent back to a
special junctor.

15



When a circuit goes through the transmission station, the four
conversation wires are extended to the station. To these four
wires must be added the signaling wires listed later in the
general description of the equipment.

The auxiliary lines, the junctions with the two-wire transit
center, and generally speaking, all circuits which do not go
through the transmission station end in the junctor assigned

to them in the switcher (outgoing junctor or incoming junctor).
Therefore, they go in two wires (for conversation) to the

input dispatcher of this switcher. To these two wires may pos-
sibly be added the signaling wires described later in the general
equipment description.

5.12. Transmission plan

Figures 1, 2, and 3 show the diagram of a two-wire circuit
leading to a two-wire switching center, a four-wire circuit
leading to a two-wire switching center, and a four-wire circuit
leading to a four-wire switching center.

These circuits are regulated as indicated in figures 4 and 5.

The end of a circuit brings about an attenuation of 0.2 N: 0.4
N of the terminator minus 0.2 N from the attenuation line which
is erased. The equivalent in terminal service of all amplified
circuits connected with a CT4 is therefore 0.45 N.

If one joins end to end n circuits, the equivalent of the link
is given by this relation:

0.2N+0.07Nxn+0.2N.

This implies the following switching rules:

a. When an amplified circuit is "ended" at a four-wire transit
center, the attenuation lines of 0.2 N are erased in the
junctor (figures 6 and 7);

b. When two amplified circuits are placed end to end, the

attenuation lines of 0.2 N remain on the link in the
junctors of the two circuits (figures 8 and 9).

5.13. Conversation circuit

The situation of the conversation circuit, no matter what the
type of link established (in the CT4) is shown in figure 13.

In each junctor, a mid-point coil is placed between the two
wires of the same channel. Its natural inductance is greater
than 50 H and its resistance is less than 800 Q>



quezano
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soyeul uotzeuTbtz0 Fo RuTod
ou ze ‘butwooutT 3e eATR AAT TFqe
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Syleuoy BuTwoour woTsstusueaz 4buryeutbTz0 snzeqs yo sebueyo 10
eqep Fo snjeqs Jo butTuesy

uot oOeITa

87



c. B8 signal (passage to supplemental code)
This signal makes it possible to introduce 10 supplemental

signals which constitute a "supplemental status code of the
called number," defined as follows: ~

number transferred

» number canceled
?

» number suspended or out of order
» number or level not used

-90, subscriber absent

This code is used in cases when, after the call has reached

a canceled line (R), a transferred number (T), a suspended or
out of order number (S), a level not used (NNU) or a number
transferred to an absent subscriber (AA), it is desired to re-
route the communication from a preceding center. From this
center, the circuits are disconnected and the call is switched
to an information and public service position (or to a recording
machine). Such a rerouting avoids the use of return pairs
between the incoming center (without manual positions) and the
center which is to handle the call, which enables the limits
prescribed for equivalents to be respected more economically.

The register of the center which makes the rerouting must "act

in tandem" for all communications destined for centers whose
handling of calls to RTS, NNU, and AA uses the supplemental

code. When the supplemental code is used, this register retrans-
mits "upstream" the BO signal for absent subscribers, and the

B2 signal for other cases.

If calls to RTS, NNU, and AA are handled at the incoming office
(by recording devices or by an operator), the supplemental code
is not used. The BO signal is sent for absent subscribers and
the B2 signal for other cases.

ad. BO signal (subscriber absent)
This signal is planned for possible use in international automatic

service. In regional and national traffic, it must be inter- .
preted as B1 (number called ringing with charge).

80



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zZeqTzosqns
wozg [Teo
Teuotzeure4UT
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xz0jzeZedo0
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queudtnbe TeuotzeureAUT
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rozexredo
tT epod--* ZT “7T® «OOL‘T + 006 TTF + TF
z03e270ed0
TT ®poo--*TTq “TTR OOL‘T + O04 ITF + OF

(OTFZFeA TeuoT}eure4uT) epoo ArejusueTduoD

@poo SeTro0b (evep [Teotzounu) (eqep AzeutuTTezd) (Z929H UT) (§¢ FO Z)
-9389 TET TRO epoo TeoTTeUNN apoo sseooy seTouenbezqg  uoTzeutTquop

83



One delayed alarm lamp is also provided (ignition delayed from
2 to 4 min) per frame or rack of incoming junctors, installed
on the circuit monitoring panel. This lamp signals that a
junctor of the frame or rack did not receive the disconnect
Signal when the subscriber called hung up.

It also ignites when one of the incoming junctors is occupied
manually. It lights in the case when, the incoming junctor
being operated in a decimal code and the communication then
using a circuit operated in MF code, the junctor has received
the signal "subscriber free without charge"; the person called
hangs up and the disconnect signal does not get through.

Originating automatic long-distance junctor

One lamp is provided per junctor on the circuit monitoring
panel; ignition occurs in the following situations:

Lamp out: junctor available
Steady burn: circuit occupied normally
250/250 flickering: junctor taken by test unit

150 (ignition)/350 flickering: junctor occupied by trans-
mission center

500/500 flickering: junctor in half-fault position

Four buttons can be used to show each of the above ignitions
for all of the circuits. These ignitions may be controled
independently of each other. Moreover, light signals are on
lever-operated wedges.

A button is installed above each light signal which is used
to show the junctor is unavailable. If the junctor is in half-
fault, @epressing this button makes this situation disappear.

With each beam of circuits there is associated a pilot lamp
whose delayed ignition (2 to 4 minutes) signals the non-recep=
tion of the request to transmit signal on one of the beam's
eircuits.

Urban originating circuits to the oT2

Each junctor is represented by a cut-off jack and a lamp on
the cut-off panel. The ignition of this lamp shows the occu-

pation of the junctor. One button per beam controls the ignition

of these lamps.
21



JPRS 70313

12 December 1977

TRANSLATIONS. ON TELECOMMUNICATIONS POLICY,
RESEARCH AND DEVELOPMENT

No.. 23.

GENERAL SPECIFICATIONS For APPLICATION OF
AYFOMATIC. SWITCHING IN TELEPHONE SYSTEMS

Release

roved for Public
‘Distribution Unlimited

~)

“20000310 115.

U. S. JOINT PUBLICATIONS RESEARCH SERVICE

TRIBUTION STATEMENT A

DIS
AP

Reproduced From
Best Available Copy

REPRODUCED BY

NATIONAL TECHNICAL
INFORMATION SERVICE

U.S. DEPARTMENT OF COMMERCE
SPRINGFIELD, VA, 22161


A3.5.

Code A
(selection code)

Code B
(status code of
party called)

Register signal codes; backward signals

Code C
(caller identifica-
tion code)

Al: Send the ac-
cess signal
and the first
two or four
digits

A2: Send the last
digits

A3: Passage to
code B

A4: Passage to
code C

A5: Send the
caller cate-
gory

A6: Normal transit

A7: Diverted
transit

A8.

A9: Congestion

AO.

Comment:

Bl: Ringing with
charge

B2: Ringing with-
out charge

B3: Busy

B4: Passage to
conversation
(only in
international)

B5.

B6.

B7.

B8: Passage to
supplemental
code

BO.

BO: Person called

absent (only
in interna-
tional)

for the forward signals.

A3.6. Line signals

Cl: Send the caller
category and the
first four digits
of his national
number (ABPQ)

C2: Send the last four
digits of the
caller's number
(MCDU)

C3: Passage to code B

C4: Passage to code A

cs.

cé.

c7.

cs.

co.

co.

The frequency combinations used are the same as those

Most of the information needed in a communication is trans-
mitted between registers by multifrequency codes defined in the

first part.

Information that can not be exchanged between

registers is transmitted by circuit junctors using line signals.

84



The subscriber first. dials the international prefix (19) and
then, after hearing'a second tone, dials a number in the format
33 XY, or possibly 33 XYZ. The digits XY are used to direct

the call to the manual international center for general traffic
for the relation considered and possibly to sections of special
positions within this international center. The. digits XY or
XYZ are analyzed at the first’ international center used, or in
some exceptional. cases, at the local international link, and

the call is routed to the manual. international center for general
traffic for the direction considered.

The following combinations are now assigned:

Netherlands 31
Belgium 32
Spain 34
Italy 39
Switzerland WY
United Kingdom Yb
West Germany 49
Luxembourg 352
North Africa 21
all other countries 19

Communications requested by a manual subscriber or by a subscriber
from the rural automatic system.

The CG operator uses a call line of the national switchboard
and dials a number in the format 16 or AB 17, which enables her
to reach an operator of the CIM for general traffic, which

is the head of the line for the direction being called.

This obligatory intervention of a CIM operator makes it possible
to locate problems or settlement of accounts, languages, and
operational difficulties (special communications) in these
centers, and consequently, to relieve the group centers from
handling these matters.

6.32. Incoming communications

6.321. Communications established without the intervention
of a French international operator

The incoming automatic international center switches the call

to the associated CT+. The call is then processed and routed
under the same conditions as a national call.

44



retransmission of charge pulses. The maximum resistance of each
wire between dispatchers must not exceed 500 2.

5.2122, Incoming junctors of urban and suburban automatic
switchers using MF SOCOTEL signalling with retransmission of
charges (line A of table).

Communications sent on these junctors. are. charged by the CTH.
The register transmits the charge rate to the junctor. The
junctor can receive nine different indications of charge rates
(seven of IP rates, 1 charge not repeated, no charge). It
counts the time and sends charge pulses to the junction. These
pulses are relayed in the originating junctor of the urban
automatic switcher.

The junctions between the urban or suburban automatic switcher
and the CT+ are three-wire junctions. The third wire is used
for retransmission of charge pulses. The maximum resistance of
each wire between dispatchers must not exceed 500 Q.

When the automatic recording of communications system is in
service, these junctors -- which may supply data needed for such
recording -- will be used to establish communications requested
by the subscriber with a meter at home. At the same time
communications will be automatically recorded and charges will
be retransmitted.

5.2123. Incoming junctors of urban and suburban automatic
switchers, using MF SOCOTEL code without long-distance charges
(line A of table).

Note: These junctors will only be used when the automatic
recording of communications feature is in service.

5.2124. Incoming junctors of automatic local group centers
connected to CT+ (line B of table).

These junctors will have the same operating properties as their
counterparts used in two-wire automatic switchers.

5.2125. Incoming junctors of the line connecting automatic
switchers of the CT2 group (line E of table).

The junctors used in junctions from this line are identical to
the’ incoming junctors-» used in urban and suburban automatic
switchers in use in the local network.



d. Junction from the CT2 without charge retransmission

e. Auxiliary MF SOCOTEL code line with automatic
recording of communications .

f. Switchboard call line of the manual long-distance
system associated with a CT2; national line call

Junctors served by incoming registers

Nine categories are listed; the ones now in use are the follow-
ing:

a. Automatic long-distance circuit using the pulse \
and decimal code system described in ANNEX IV,
coming from a CG of the regional transit zone of
the CT4

b. Automatic long-distance circuit using the pulse and
decimal code system described in ANNEX IV coming
from a group center outside the regional transit
zone

c. Group circuit using the pulse and decimal code system
described in Annex IV

d. Group circuit using the MF SOCOTEL multifrequency
system described in Annex III

e. Automatic long-distance circuit, MF SOCOTEL code coming
from a CG of the regional transit zone of the cTy

f. Automatic long-distance circuit, MF SOCOTEL code,
coming from a CG outside the regional transit zone

g. Switchboard call line for operators of the
manual center associated with the CT+ (urban,
regional, national communications)

h. Inputs of the associated international center.

5.212. Incoming junctors served by originating registers

5.2121. Incoming junctors of urban and suburban signaling
aurometic switchers in use in the local network (line A of
table).

Communications sent on these junctors are charged by the CT4.

The register transmits the charge rate to the junctor. ‘The
junctor can receive nine different indications of charge rates
(seven rate levels sent by periodic pulse, charge 1 not repeat-
ed, no charge). It counts the time and sends charge pulses to

the junction. ‘hese pulses are relayed in the originating junctor
of the automatic switcher.

Junctions between the urban or suburban automatic switcher and
the CT4 are three-wire junctions. ‘The third wire is used for



Annexes:

Annex TI

Annex II

A2.1.

A2.11.
A2.12.

A2.2.

A2.21.
A2.22.

Annex III

Annex
Al.1.

Table of Contents

SRCT-R6/SOCOTEL-S1 type Signaling Systems

Pulse and Decimal Code Signaling System of the
Automatic Long-distance Service

Originating communications

Signal transmission and reception
Signal code

Incoming communications

Different signals transmitted
Pulse duration

SOCOTEL Multifrequency Signaling System applicable
betweeen Crossbar Centers

Signal categories

Register signals

Clauses concerning transmission for multifrequency
signaling transmitters and receivers

Register signal codes. Forward signals

Register signal codes. Backward signals

Line signals

: SRCT-R6/SOCOTEL S1 type signaling systems

Links

Group center to sector center
Intermediate center to sector center
Group center to intermediate center

57



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40



A3.263. C signals

These signals are used to ask the category and the number of
the caller. They may be sent at any time during establishment
of the communication if they’ aré preceded by the Al signal
(passage to code C).

The caller's category code, used to answer the C1 signal (or
the A5 signal) has, like the B code described above, the capa-
pility of introducing, using the C8 signal, a supplemental
code. This code may use one or more digits, which will be
transmitted after the 8 frequency combination (f1 + f7).

A3.27. International traffic

In international traffic, the use of the supplemental frequency
£11, in association with the five code frequencies, makes it
possible to have five supplemental forward frequencies defined
as follows:

Signal no 11 (f0
Signal no 12 (f1
Signal no 13 (f2
Signal no 14 (£4
Signal no 15 (f7

call to code 11 operator
call to code 12 operator
eall to maintenance equipment

teeet
Hy Hh hb Rb Bb
Be222
ereerearaereer
DOCS

won

= end of numbering.

Moreover, after reception of the A2 signal (send the last
digits) the originating register systematically induces passage
from signal transmission position to reception position when
there are no more digits to be sent. The later registering

of a new digit to be transmitted causes this digit to be
transmitted, then a return to receiving position.

Signals 11, 12, 13, 14, and 15 forward will be monitored by
the control frequency fc.

Generators and receivers of the frequency f11 only have to

be provided for equipment to be used with international traffic.

A3.3. Clauses concerning transmission for multifrequency
Signaling transmitters and receivers

These clauses are defined in the general technical specifica-
tions.

AZ.4. Register signal codes; forward signals

81



5.2734. Automatic decimal call sender

This device has 10 junctors which may be linked, via the inter-
mediate dispatcher, to 10 vertical units of selection elements,
and to 10 horizontal outputs of originating register searchers.

On each line this sender may compose a number with a. varying
number of digits, but never over 10. On one line, the number

is made up by buttons and on each of the nine others, it is done
by strapps.

Calls may be sent to automatic response junctors of the center
or of. a distant center.

When the calls are sent to the automatic response junctors of
the center, on one line which the operator selects by pushing
buttons, a simulated conversation test is made, checking in turn
the reception of the 450 Hertz current emitted successively on
the two channels by the response channel. On the nine other
lines, the test consists of checking the correct exchange of
Signaling up to and including the hanging up signal.

When the calls are for automatic response junctors of a distant
center, the test is limited to a signaling exchange.

5.2735. Automatic response junctors

Ten automatic response junctors are assigned to local calls and
two junctors per test rack are assigned to incoming calls.

The automatic response junctors assigned to local calls consist:
of a single beam with a three-digit number: 772 or 992, depend-
ing on the number series of the hypsometer (77 or 99).

The automatic response junctors assigned to incoming calls have
six-digit numbers or eight-digit numbers in the series reserved
for the hypsometer (773 CDU or 993 CDU). CDU may be selected
as desired. The indicator AB, which may be added, indicates
the department where the switcher is installed.

The response junctors for local calls and for incoming calls
give the response signal, in conversation position emit a
permanent tone at 450 Hertz for 20 to 40 seconds, and give the
hangup signal of the person called.

5.2736. Test and maintenance of automatic long-distance
circuits from the test unit

28



6.322, Communications established by a French inter-
national operator

The incoming circuit is an automatic circuit.

The code 11 and code 12 operators call lines are accessible only
by automatic international centers to which the incoming auto-
matic international circuit is connected. .

When there are several beams between a foreign country and France
ending in several different French international centers, the
foreign operators dial the appropriate number (N1) to reach the
code 11 or code 12 operators of a specific French international
center. In the originating country, this number makes it pos-
sible to select the beam leading to the desired French interna-
tional center. Within the French network, it does not make it
possible to reach an international center other than the one
where the incoming. call circuit ends.

The N1 numbers are the following:

Paris M1
Bordeaux N1
Lille TM1

Lyon N1
Marseille Ni
Naney TM1

Nice TM1
Strasbourg M1

WOW ONINW=

Code 12 operators can be called individually. However, at low
traffic times, individual calls are indiscriminately directed to
concentration positions.

The code 11 or code 12 operator can establish an incoming commu-
nication destined for any subscriber in the French network, and
in an international transit center, an international transit
communication.

To avoid any problem in operation, incoming calls for an individual
code 12 operator will only be routed if the N1 number received

is actually the correct one for the incoming head of the line
center.

The incoming circuit is a manual circuit.

The French international operator has the same facilities avail-
able as a code 11 or code 12 operator enabling her to establish

45



This device consists of incoming lines connected with the
first stage of selection and one outgoing line connected with
the last selection stage.

The number (six or eight digits) may be composed as desired
within the limitations indicated below, by using eight manual
switchers with 11 positions.

The tests are designed to check that the reception of the
number (in decimal code), the exchange of internal signaling,
and the transmission of. selection series by decimal senders
(outgoing selection) are correct.

The device is permanently linked to a vertical position for each
of the selection elements.

To avoid immobilizing a regional series, a number from the
series assigned to the hypsometer will be used: 771 CDU or 991
CDU; CDU may be selected at will.
The device is also permanently linked to each group of register
Searchers. A light indicator shows at each moment the number
of the frame with which the device is working.
Calls may be sent in succession to different groups of register
searchers or, on the contrary, they may be sent repeatedly to
the same group.
A counter indicates the number of tests done.

5.2733. Automatic test of junctors-chargers
This automatic test device permits:

Either general testing of all Junctors-chargers;
Or individual testing of a given junctor-charger.

The test affects only the "charging" function. For this, the
ieee rates for each charging level are checked a4 test
eycles).

When an incident occurs during a test, it is possible to use the
recording device to register the anomaly found.

At the end of recording, the test device moves to the following
junctor.

27



Annex II: Pulse and Decimal Code Signaling System of the
Automatic long-distance Service

A2.1. Originating communications
A2.11. Signal transmission and reception
A2.111. Signalling modes

As soon as an available circuit of the beam selected is taken,

signals are exchanged on this circuit with the corresponding
center, using the signal code to be defined later.

Depending on the particular circuit, signals are transmitted:

a. In 50 Hz alternating current (voltage under vacuum 100 V,
impedance adjustable from 200 to 600 2 on each wire);

b. In 48 V direct current on the two line wires which act on
an outside signaler (supplied and installed by the tele-
communications administration) 3;

Cc. By grounding of a TRON control wire which acts on an
appropriate signaler (supplied and installed by the tele-
communications administration).

The signals received from the center served by the circuit used
or by the last LGD station will be of the same type, that is,'
they will be transmitted:

a. In 50 Hz alternating current (voltage above 20 V at the
limits of 600 2 + 2 MF);

b. In direct current - 48 V on the two line wires supplied
by an outside signaler (installed by the telecommunications
administration).

c. Or by grounding of a RON control wire by an appropriate
signaler (supplied and installed by the telecommunications
administration).

A2.112. Signaling in 50 Hz current
Transmission
The common source of 50 Hz alternating current at 127 V will

be reduced to 100 V on the circuits used and will have a
negligible internal impedance. before 800 Q.

64



Ss.

If there is an associated CI, calls are routed to this
center without going through the CT4.

Key for Routing Table:

1.
lb.
2.
3.
4.
5.
6.

7.

8.
9.

10.
1.

A.
B.
Cc.
D.
E.

F.

G.

H.
I.

J.
K.

5.1.

Incoming

Outgoing

International automatic originating communications Rx and Nx
Local automatic communications (connected to CT4)

Junctions to associated CI (for local centers)

Lines to centers and suburban centers of CT4

Operations of manual long-distance system associated with
cT2

B operations of manual long-distance system associated
with CT2

International operations in CT associated with_CT+
Junctions to associated CI (for CG of the ZR /Regional
Zone

Junctions to associated CI (for CTR)

Junctions to CT2

Auxiliary lines from urban and suburban centers for
regional and national automatic traffic

Communications from automatic local group centers (con-
nected to CTH)

Incoming long distance automatic communications from CG
of the regional zone.

Incoming long-distance automatic communications from the
CTR

Junctions from the CT2 for routing calls from automatic
local group centers for regional and national automatic
traffic.

Junctions from the CT2 for routing calls from long-dis-
tance automatic communications and operations of the
manual long-distance system (LAC, regional link)
Junctions from the manual long-distance system (LAC,
national link)

Junctions from the CI

Auxiliary lines from urban and suburban centers for
international traffic

Junctions from the CT2 for routing calls from automatic
local group centers for international automatic traffic
"Keyboard" call lines for operators of manual centers
associated with CT+

Transmission Conditions

5.11. Auxiliary lines. Junctions and Circuits.

All auxiliary lines, junctions, and circuits switched in a
four-wire transit center or in an international center have
a four-wire arrangement in the switcher. .

4



Incorrect call. Number incomplete.

If the number dialed does not get through after connection of
the register within a period set by the 10 s timing device,
the register is disconnected without sending any signal back.

Level not used
Cf. Originating register.

Non-completion of internal selection
Cf. Originating register.

Reception of overload signal in multifrequency code
Cf. Originating register

Non-reception of end of selection signal

If, after sending the last digit, the end of selection signal

is not received within a period of time set by the timing device
(2 min cams) the decimal auxiliary gives the "busy" signal to
the register; the MF SOCOTEL auxiliary gives the "overload"
signal. {

Forced Disconnection

In all cases in which the incoming and transit register sends
an end of selection signal other than "number called free,"

it must receive the disconnect signal. A timing device (10 s
cam) is used to force a disconnection without sending a signal
back in case this signal might not be received.

5.233. Translator

There is planned a single type of translator usable by CT4
switching lines. However, because of different routing condi-
tions, the originating register and the incoming register have
separate access to translators used either for origination, or
for incoming and transit traffic.

The general conditions of operation of the translator were given
in section 23.

The equipment of a translator must include a minimum of 300
paths. A path is determined by routing and charging. Moreover,
each diversion, characterized by routing and charging, requires
the use of one path.

18



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55



The A? signal indicates to the originating register that a diver-
sion was made, and that it must modify the access signal (which
becomes 2 or 4, instead of 1 or 3) to prevent a later diversion.

The A6 signal fixes for the originating register the interpre-
tation ofthe following A2 signals without using the A6 signal.

Therefore, the A2 signal means: "Send’ the last four. digits (MCDU),"

while the A2 signal received after the Al signal without an
intervening A6 signal means: "Send the last digits (MCDU, CDU,
or DU)." .

f.. AQ signal (congestion)

This signal is transmitted by the register of an incoming center
or transit center which finds either an internal blockage or
that no normal or diverted channel is available. It will be
interpreted at the originating center according to the capabili-
ties of this center (rerouting at origination, return to an
operator, recording machine).

A3.262. B signals

These signals indicate to the originating register the status
of the line called. They are transmitted after the moment when
the last circuit permitting use of the register signals is in-
formed of this status. They are preceded by the A3 signal
(passage to code B).

a. B2 signal (line called ringing without charge)

Through the introduction of this signal, the response signal
(line signal) may be transmitted during the establishment of

a non-charged communication, thus giving correct supervision of
the person called. Moreover, the establishment of allowance
cards in the case of calls made by telecommunications adminis-
tration employees from the phone of the subscriber to test or
maintenance tables becomes unnecessary.

b. BY signal (passage to conversation)
This signal is scheduled for possible utilization in international
automatic service to permit an immediate disconnection of the
TASI channels during return call transmissions which will be
transmitted at the point of origination.

In regional and national traffic, the return call tone will al-
ways be given by the incoming end.

79



These signals must ensure the connection of mechanisms, super-
vision of the communication, disconnection, and possibly permit
the recall of the party called by an operator.

The transmission of information can be done either by sending
pulses or by modifications of permanent currents resulting from
status changes made at the ends.

The junctors must be designed so that the common mechanisms,
particularly the registers, can function with junctors of differ-
ent types, and so that the passage from one type of signaling to
another on the same circuit may be done by a simple replacement
of the junctors at the ends, without resulting in a modification
in the structure of the common mechanisms.

The following tables define the codes that may be used for line
signaling. These tables show a pulse code and a de (status
change) code used for signaling in urban networks.

A3.61. Line signaling. Pulse code

Duration (in ms) an es

Meaning of signals 4; i _| Transmission
: direction of trans- ! tolerances

mission
Connection = 20%
Response by party iso
called . — + 20%
Party called hangs _ 159350 , 189350 150 + 20%
up et (150 + 350) + 6% — 15%
Party called . _ 150 =~ wo
recalled ~ — °

. 750 0%
End i 4 50%

The connection signal must not be transmitted less than 100 ms
after cessation of the transmission of the end signal.

Depending on the particular circuit, the signals transmitted
consist of:

a. Pulses of 50 Hz alternating current on the two line
wires. (voltage under vacuum 100 V, internal impedance
of the power supply 800 2)

85



Al.31. b.

Sub-center to connection center

Status code (direct current)

Phase Sub-center Connection center
Rest 6002 loop 6702 loop
Connection Battery pulse on 670 1 loop
A and ground on B
for 100 m/s
(4802 per wire)
then 600M loop,
then power supply
Request to 600 1 loop Power supply and tone
transmit
Numbering Variation in Power supply
resistance
12,000/600L% ;
rate of dial
Ringing 600 £1 loop Power supply and
return call
Busy 6002 loop Opening of power supply
Charging 600 $1 loop 100/100 pulse in alter-

Caller hangs up
Disconnect
Return to rest

Comments:

12,0002 loop

After disconnec-
tion, 600S1 loop

nating current (in //
on the two line wires).
Transmission 80 v +

15 3

Power supply
Opening of power supply
670fL loop

1. The value of the 6702 loop in the connection center
corresponds to the maximum existing in the various sys-

tems.

It has no influence on the functioning of the
sub-center.

2. The counting pulses and the interval between two consecu-
tive pulses must last at least 80 ms.

62



C72 e744

O45.

Fig: 6 Grevit amplitié avec C2

« woe
lerminé”au Cr4

Figure 6: Amplified circuit with
cT2 "ended" at CT4

CTH CT4

Oey 0,2N

45N

Fig: 7 Cirewit omplifie entre deux C4
“terminé” dans les deux CI4&

Figure 7: Amplified circuit between two cT4
“ended" in the two CT4

35



3. With active pulses spaced by an interval of a minimum
duration of 20 ms, the duration of the active pulse is
the complement of the total duration of a pulse defined
by. the two extremes listed above. .

Cc. Disconnect signal: a minimum of 450 ms
The first maneuver tone scheduled will not be transmitted.

The second scheduled maneuvering tone will only be transmitted
upon reception of the prefix 16 if a period of. time is required
between the reception of this indicator and. the reception of

the following series of pulses, and not after a prefix consisting
of a series of 12 or 13 pulses.

After sending the end of selection - ringing signal, or when
such a signal is not systematically sent at the end of select-
ion, the return call tone is sent on the long-distance circuit
until the response of the person or service called.

The response signal -- which starts the charging process in the
originating central office -- must not be sent when this is a
call destined for a line that has been canceled, transfered, etc.,
or a call switched to information after some problem (incorrect
prefix, level not used, etc.) but the operator or the recording
device (see 4.14) must in this case simply cause the cut-off

of the return call and establishment of conversation circuit,
without sending the response signal.

Annex III: SOCOTEL Multifrequency Signaling System applicable
between Crossbar Centers

A3.1. Signaling Categories

Signals exchanged for the establishment of a communication may
be classified in two categories.

A3.11. Register signals
These signals provide transmission of information concerning
numbering and the nature and status of subscribers! lines. They
are exchanged between common circuits (registers, common trans-
mission or reception mechanisms) during the establishment phase
of the communication.

A3.12. Line signals

These signals handle connection of mechanisms, supervision of the
communication and disconnection. ‘They must be transmitted even

75



cre J, O74 dg ere
W2N O;2N
Ww WM —+
50N
Fig: 8 Commutation au. C74
ge deux circuits avec deux C72
Figure 8: Switching of two circuits
with two CT2 at the CT4
cry cT4. era
i= O2N 052N O92N
Cc Wy AWW AAW

50N

Fig:9 Commutation au Cl& dun circuit avec C1
et J’un circuit avec C2

Figure 9:

Switching of one circuit with
cT4 and one circuit with CT4~

at the CT2

36



cc (Skv) I)
(ch Al) { ) 76) @, ciM

Figure 9.

6.43. Charging

Switching equipment is designed to handle 10 different rate
areas. (these may be extended to 20). A maximum of 20 dif-
ferent charge levels can be used (no extensions planned).

A reduced rate may be charged during low traffic times on all
or part of the directions in service. This is obtained by mul-
tiplying the charging period for the directions concerned by

a single coefficient.

6.5. Traffic survey for drawing up international accounts

In entirely automatic operations; accounts between different
agencies are established on the basis of the total lengths of
conversations (CCITT blue book, note Q 50). International ac-
counts for semi-automatic calls are based on tickets made up by
the originating operators. Consequently, the counters used for
recording the length of the communication record only the dura-
tion of entirely automatic communications. The duration of com-
munications at low rate times may, if necessary, be recorded

on separate counters.

The length of conversations is measured by counters in the des-
tination countries. When the destination country has several
different charge zones, these measurements are made by the charge
zone. If there are several beams going to the same charge zone
of.a particular country, only a single survey is made.

Border traffic is not included in these traffic statements;
each country keeps its own receipts.

In all other cases, entirely automatic traffic is included in
the statements, whatever the routing, in the first international
center where it appears, or in the local international link if
one is used.

51



E. The number of "no answers" disconnected within a time
less than 15 s after the end of selection.

F. The number of "no answers" disconnected within a period
of time above 15s after the end of selection.

G. The number. of calls for which the end of selection signal j
is not. received 15 s after reception of the last digit.

H. The number of calls leading to disconnection within a
time under 15 s (after reception of the last digit).

I. The number of calls with disconnection during dialing
phase.

J. The number of calls that can not be sent because of
occupation of the circuits of the subscribers called
or because of disconnection by the register (sent
back in fault).

Calls in categories D through J are totaled on counting relays.
When one of these counters arrives in position 10, the analyzer
transmits all the data it contains (A to J) to the recording
device.

Observations on Originating Junctors

The information obtained by observatimof the originating

junctors is identical to that obtained’ by observation of the
incoming junctors, except for the duration of "dialing+ selection"
which is then limited to the time elapsing between connection of
the originating junctor and reception of the end of selection
signal.

Selection of Calls

Whatever the type of junctor observed (originating or incoming
junctor) and the signaling code (decimal code or MF code), the
analyzer has a system for registering numbers which can be used
to observe, if desired, onlythose calls destined for certain
addresses characterized by the first two or four digits (AB,
PQ, or ABPQ).

The series of prefixes observed are made up by mobile links
made in a dispatcher.

It is possible either to observe only calls thus selected, to
eliminate these calls and to keep all the others, or to make no

24



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54



Al.32. a. Connection center to sub-center

Pulse code (50 Hz alternating current)

Phase cR ———» SC
. 100 1000
Connection 7 ——> 100
Request to transmit Palme
Numbering SO, 50_%, s0_2, so _*
Busy Pan
. . 500
Ringing : <—_
* . . 100
|Picking up receiver <—
500
Hang-up __ <__
Call back im,
. 200
Disconnect : am,

Al.32. b. Sub-center to connection center

Pulse code (50 Hz alternating current)

Phase sc ———» CR
. 4100
Connection —___ — a a
. 6633 66
Numbering —_o =
Charging Passa
500
Hang-up —.
Di 1000,
|Disconnect <——

63



CONTENTS (Continued)

6
6
6

6

.15. International Center for Limited Traffic...
.16. International Vicinity Center.....
.17. CLI [Local International Originating Link].
6.
219, Rear Zone...cccceeeveoeee

18. Ch.AI [International Access Link]........

6.20. International Center: Routing Table.........
6.2. Transmission Conditions.........
6.21. Presentation of Auxiliary Lines, Junctions, and Circuits......
6.22. Transmission Plan.
6.23. International Number..
6.3. Operating Mode....
6.31. Originating Communications.....cceccccceeccccceccccccsececcces
6.32. Incoming Communications.. eens errr
6.4. Routing, Signaling.....ccceeeccccecccccccencccreseercessseresesees
6.41. The CTR is an Automatic International Center...........
6.42. The CTR is Equipped With a Local International Link.

6

6.5.

-43. Charging...

Traffic Survey for Drawing Up International Accounts.......eseeeee



It consists of the local number of the subscriber preceded by
the long-distance indicator’. When the long-distance prefix

is. published as if it were part of the long-distance indicator,
the number called consists of the local number preceded by the
long-distance indicator with the long-distance prefix deleted.

6.3. Operating Mode
6.31. Originating communications

6.311. Groups without access to the automatic international
network

To obtain an international. communication, subscribers call a
national operator using the directions given them locally.

The national operator of the originating group center connects

the calling subscriber with an international operator of the
manual international center which is the head of the international
line, or transmits the request herself (depending on instructions
given at her center), either manually or by dialing a number in
the format AB17 if the group center belongs to the regional
transit zone of the international center.

6.312. Groups whose center has access to the automatic
international center

Entirely automatic communications

The subscriber dials the international prefix (19) and then,
after hearing a second tone, dials the international number of
the person he is calling.

Communications requested by an automatic subscriber requiring
the intervention of a French international operator.

This is the case with communications established through a
manual international circuit, special communications, ete.

1. In France the local number + area code is the eight-digit
number (ABPQMCDU). ‘The long-distance indicator in the
provinees consists of the first two digits of this number
(AB); in the seven-digit zone of the Paris region, it con-
sists of the digit 1 which precedes these seven digits,
and which occupies position A.

2. In France: 16. In most other countries: 0.

43


An international center always. coexists with q.four-wire transit
center. It can establish all or part of the connections indica-
ted in the preceding table. The letters on this table show the
routing features and have the following meanings:

a. Entirely automatic. connections and those which do not
require the intervention of a foreign operator on the
line are open only to subscribers.

db. Only incoming circuits connected directly with the cTh
have access to the international automatic center.

c. Communications for urban and suburban centers, local group
circuits, and regional and national long-distance automatic
circuits are routed on this beam.

d. International transit.
e. These operators can only be called by foreign operators.

f. This beam is open when traffic or transmission conditions
so warrant. If it does not exist, links are handled by
national circuits accessible both from CT4 and from the
CI leading to the distant CT+ associated with the CI which
is head of the line for the direction being called.

6.2. Transmission conditions

6.21. Presentation of auxiliary lines, junctions, and
circuits

Refer to paragraph 5.11.
6.22, Transmission plan

The national part of an international link creates an attenuation
of 0.25 N + 0.05 N x n between the four-wire ends of the inter-
national circuit and the terminator. n represents the number of
national long-distance circuits entering in the link. This
attenuation is distributed as shown in figures 10 and 11.

Figure 10: . The termination at the international center brings
about the clearing of the 0.2 N line. It thus introduces an
attenuation of 0.40 + 0.05 - 0.20 = 0.25 N.

41



used. in the circuit. If necessary, a pure resistance of 600
Q in a serial arrangement with a capacity of 1 MF will be ac-
cepted as terminal impedance.

In addition, the reception equipment must be entirely separated
from the retransmission circuit toward. the automatic switcher.
In all cases the continuity of the line wires will’ only. be en-
sured after transmission or reception of the end of selection
signals. Whatever the origin of the call, the routing tone

must be transmitted to the caller at the end of numbering

with a commercially acceptable level until reception of the

end of selection signal (level of permanent transmission between
170 and 260 mV measured at the limits of 600 2 at the incoming
part of the circuit, with the circuit eliminated).

Then, in order to avoid that transient currents (originating in
the closing or rupture of direct current circuits on line wires
in the switcher either before or after transmission of signals
may prevent the correct operation of the signal receiver located
at the other end of the circuit, the following steps will be
taken upon transmission of a signal in the circuit:

a. The circuit will be separated from the center 30 to 50
ms before the start of transmission of the signal in
the circuit;

b. The circuit will only be connected in the center 30 to 50
ms after the end of signal transmission in the circuit.

A2.12. Signal code

A2.121. Case of an originating communication with the
national automatic service

A2.1211. Connection signal; request to transmit signal
The connection signal lasts 100 ms.
As soon as the corresponding long-distance center can receive
and handle the numbering signal, it responds to the connection
signal by sending a "request to transmit" signal lasting 100 ms.

The interval between the connection signal and the request to
transmit signal must be a minimum of 150 ms.

Upon reception of this signal, the numbering signals are trans-
mitted with a minimum delay of approximately 250 ms.

66



5.2312. Categories of Incoming Junctors

The originating register can discriminate nine categories of
incoming junctors tor. 211). These categories also indicate to
the originating register if the automatic recording feature
should be used.

5.2313. Digit reception
Decimal code

For regional communications, the register receives the six
digits of the regional number from the urban center.

For national communications, the register receives from the
urban center the indicator 16 or a series of 12 pulses. It
sends the second tone to the subscriber and registers the eight
figures of the national number.

For a communication to be sent to special services, it can
register a number with two digits (1Q) or four digits (1 Qc
or AB1 Q). In the latter case (ABI Q), the number is preceded
by the prefix 16 or by a series of 12 pulses.

MF SOCOTEL code

For a regional communication, the register receives from the
urban center the six digits of the regional number preceded
by the access code.

For a national communication, the register sends to the urban
center the signal At.(send the access signal and the first two or
four digits). In return it receives the A5 Signal (two-digit
call), followed by the indicator 16 (1 + 6). It sends the

A3 signal (passage to code B) followed by the B1 signal (number
called free with charge) in order to permit the release of the
urban register, The originating register sends the second tone.
Pulses are received in decimal code.

5.2314. Call to translator
The register is equipped to transmit to the translator:

a. 2, 3, 4, or 5 digits. The first connection may take
place after reception of the first two digits. If the first

two digits are not enough to identify the routing conditions of
the call (attraction of path relays), the translator asks the

11



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53



b. Pulse code (50 Hz alternating current)

Phase

faa

Connection

Request..to..transmit|—
Numbering
Ringing

Busy.

100 ms

<

——- (100/100/100)

——> 100 ms

Call release...
{
Response requested

<——- 100 ms

Hang-up_ requested

<—-~ <—. (100/233/100)

Call back | ——> 100 ms
Di nn 4 ., More than
A2.2. Links

Sector center to group center

Sector center to intermediate center
Intermediate center to group center

a. Status code (direct current)

cs CG
cs cL
Phase cr CG
Rest 500 f. loop 500fL loop
Connection Ground on A; Weak loop: 50012

battery on B
Ground on A;
battery on B
At center of sec-—

Good circuit

Request to

transmit tor; maneuver tone

Numbering Reversal of power
supply (at the
rate of dial)

Busy Power supply

Ringing Power supply

Charging Power supply

Caller hangs up Reversal of power

supply
Disconnection Power supply
requested
Return to rest Circuit open then
5002 loop

59

12,5002 loop
500 £1 loop

500 1. loop

Opening of loop
Return of call

+ 48 V in mid-point
500 (2 loop

Opening of loop

5002 loop



of a relay, it is moved to a second beam. The first beam may
be formed of individual. junctions and the second beam of common
junctions.

In case of overload by marker, no modification is made in the
program communicated by the translator to the register.

Overload by register

This overload occasions: a. new consultation of the translator.
The program of the register may be modified: for example, it
is possible to pass from sending back six digits to sending
back eight digits and to order the sending of the access code
"channel diverted."

c. Outgoing Selections

Depending on the category of the outgoing junctor, the register
uses either an auxiliary decimal code or an auxiliary MF SOCOTEL
@de.

Auxiliary Decimal Code

At the first consultation of the translator (upon reception
of a sufficient number of digits), the register is informed:

Of the possible sending of a translated prefix. In this
ease, all or part of the digits of the number received
are sent back, which may or may not be preceded by a
series of more than 10 pulses;,

Of the possible sending of the series of over 10 pulses
which immediately precedes the sending of the digits of
the number (entirely or partially);

Of digits of the number to be sent. Upon receipt of
a national number, the following may be sent back:

ABPQMCDU
or  BPQMCDU
or PQMCDU
or MCDU
or DU
or U

13



JPRS: 70313

12 December 1977

TRANSLATIONS ON TELECOMMUNICATIONS POLICY,
RESEARCH AND DEVELOPMENT
No. 23°

GENERAL SPECIFICATIONS. FoR APPLICATION OF
AUTOMATIC SWITCHING. IN TELEPHONE SYSTEMS

Paris CAHIERS DES CHARGES GENERALES D'EXPLOITATION DES AUTOCOMMU-
TATEURS TELEPHONIQUES in French 1968-1969 pp 85-149

[Chapters 5 and 6 and three annexes of a document published in
French by the Ministry of Posts and Telecommunications]

CONTENTS PAGE

CHAPTER 5: THE FRENCH NATIONAL FOUR-WIRE SWITCHING TRANSIT CENTER...... 1
5.1. Transmission Conditions.......ceceeeececc ces ecec eee cecseneeeeneeee

5.11. Auxiliary Lines. Junctions and Circuits........cceeeee eee ees
5.12. Transmission Plan....
5.13. Conversation Circuit.
5.14. Link Stability Before Conversation.......scceccecceccccucceece

5.2, Equipment... .ccccce cece cece cece cece e eee e cece eenseceeesceneseeeese 6
5.21. Incoming Junctors . 6
5.22. Conversation Line - 10
5.23. Registers.......... - 10
5.24. Originating Junctors...........6. - 19
5.25. Monitoring of the Automatic System « 20
5.26. Counters... sees « 22
5.27, Traffic Observation.........ceeeeeee 22

CHAPTER 6. THE INTERNATIONAL CENTER..........

6.1. Definitions...

6.11. International Center....... cece cece cece cece eee ceeececececerece 37
6.12. CIA [Automatic International Center]
6.13. CIM [Manual International Center]...
6.14. International Center for General Traffic.....

“an [III - INT - 140]



ors

O2N

0,250

(Circuit non terminé av cra)
Circuit not ended at CT4

Fig: Cirewit 2 fils ow 4 file

avec centre de commutation “ afils”

Figure 4: Two-wire or four-wire circuit with
two-wire switching center

C74

,2N

05 Nv
I
(Crevit 4 fils non termine) |
Four-wire circuit not ended

Fig:5  Grewit 4 fils
avec. centre de commulstion “& fils”

Four-wire circuit with four-wire

Figure 5:
switching center

34



outside the time of utilization of the recording mechanisms ,
by junctors of circuits using ‘the customary transmission modes:
50 Hz, dc, voice, or interband frequency signaling).

A3.2. Register signals
A3.21. Type of signaling

The system is of the "caller-controled" type using five signal-
ing frequencies and one control frequency. A sixth signaling
frequency is scheduled for use of the system in international
traffic.

A3.22. Frequency code

Code 0 - 1-2-4 - 7 in 2 among 5 using the 5 frequencies (in
hertz):

fo = 700, f1 = 900, f2 = 1100, fh = 1300, £7 = 1500.
The value of the control frequency is fe = 1900 Hz.

This code is used to obtain 10 multifrequency signals. The
frequency f11 = 1700 Hz is used to create 5 additional forward
signals (code O-1-2-4%-7- 41 in 2 among 6) for inter-
national traffic.

43.23. Mechanism of signal exchange between registers

When two registers are present together, the transmission of a

two-frequency signal is done by one of the registers; the other
is in reception position for these frequencies. Control of the
signal transmission is done by using the control frequency, as

follows:

The "downstream" register, for example, transmits a back signal.
The "upstream" register, upon recognizing this signal, transmits
forward the control. frequency fe. When the downstream register
recognizes this frequency, which gives it the control that its
signal was received, it interrupts the transmission of this
Signal. The recognition of the cessation of the signal by the
upstream register causes the end of transmission of the frequency
fe.

Each of the two registers controls directlyon the line the dis-
appearance of frequencies or of their possible echos before a
new signal is transmitted.

76



Total occupation of beams
One lamp per beam signals that there remains at most 3, 2, 1,
or 0 circuits available in the beam. The alert limit may be
operated separately for each of the beams at one of these
four values.

5.26. Counters

5,261. Traffic counters per beam

A set of counters (or several sets for large beams) is associ-
ated with each beam of circuits.

This set of counters, controled by the junctor, adds up all
actual communications. Each set consists of two counters:

one totaling counter
one partial counter

Operation and shutdown of all the partial counters is controled
by a single device for all the counters. In addition, operation
and shutdown of each partial counter may be ordered, under the
control of this device, by a device for each counter. Partial
counters may be set back to zero.

5.262. Traffic coumters on switching mechanisms

A portable model equipped with 40 counters with return to zero
connected by flexible cord and closing relay to the mechanism
connection groups makes it possible to count the number of con-
‘ nections on each of the following mechanisms:

registers
translators
receivers
senders

marking channels

5.263. Congestion counters
A counter is associated with each beam. It is used when the
call placed can not be routed because of total occupation of
the bean.

5.27. Traffic Observation

Two traffic observation devices may be used. The first employs
conventional equipment; the second uses electronic equipment.

22



NOTE

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Headlines, editorial reports, and material enclosed in brackets
{] are supplied by JPRS. Processing indicators such as [Text]
or [Excerpt] in the first line of each item, or following the
last line of a brief, indicate how the original information was
processed. Where no processing indicator is given, the infor-
mation was summarized or extracted.

Unfamiliar names rendered phonetically or transliterated are
enclosed in parentheses. Words or names preceded by a ques-
tion mark and enclosed in parentheses were not clear in the
original but have been supplied as appropriate in context.
Other unattributed parenthetical notes within the body of an
item originate with the source. Times within items are as
given by source.

The contents of this publication in no way represent the poli-
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an incoming communication, and in an international transit center,
an international transit communication. ~

6.4. Routing, Signaling

This section concerns only groups (either partially or. totally
automated) with either an automatic international center, or
a local international link, or an international access link.

6.41. The CTR is an automatic international center.

6.411. Communications requested by subscribers of the
group center and of the automatic international
center's group.

Upon reception of the 19 in the urban register, the call is
routed directly to the automatic international center (without
going through the CT4, except for S1 automatic switchers directly
connected to the CT+) with which the urban, urban transit, and
STCT or S1 automatic switchers have direct connections. The

CIA sends the second tone and the subscriber dials the following
digits in accordance with the directions given him.

If the communication is entirely automatic and is destined for

a country directly accessible from this international center,
the call is routed on the appropriate beam for the direction re-
quested (with or without the possibility of overload, depending
on whether or not it is a transversal beam or normal beam).

If the communication is to be established through an associated
manual international center, the call is routed directly to
this center (figure 1).

46



Additional tests

In addition to the measurements indicated above, the test unit
can also perform dc measurements normally done from a test
table.

5.2737. Test using AAMT Zhutomatic Transmission Measurement
Equipment/

This test is done between two terminal transmission stations,
via the two switching centers.

In origination, access to the junctor is provided by the
mechanism seeker.

When the mechanism seeker is engaged, it is shown as busy for
the test unit. All the junctors to which it provides access,
therefore, can not be returnéd to this unit.

After sending each junctor to the AAMT, the test unit has
priority for connection and return of a junctor. The junctor
is returned by a relay, which releases the mechanism seeker
of the AAMT.

Upon arrival, the access to the AAMT is provided by a junctor
behind the selection of the incoming group.

The incoming AAMT is called by the originating AAMT using a
four-digit number (no matter what the code used on the circuit
(9988 or 7798).

In multifrequency signaling, the number is preceded by the
regional access code, Al.

For a more detailed description of maintenance on long-distance
circuits, refer to the SOCOTEL specification: "Specifications
concerning Maintenance: of Long-distance Automatic Circuits of
the French Telephone Network."

30



It provides charging for the international automatic communi-
cations that it routes and, in some exceptional cases, if cir-
cumstances warrant, it directly handles international transversal
or vicinity circuits.” .

This link also handles routing of international communications
coming from the international access links that it handles.

6.18.  Ch.AI /International Access Link/

This is a link which enables the automatic subscribers of a
group center and of local centers of this group to obtain
automatic international commmications and to call international
operators directly.

It does not provide charging, but it retransmits pulses coming
from an automatic international center or from a local inter-
national link.

6.19. Rear zone

The rear zone of a general traffic international center consists
of all the transit zones, which are in principle regional,

whose international traffic for the direction considered is

sent (in entirety or only overload traffic), both originating and
incoming communications, by the international center being con-
sidered. The rear zones of general traffic international centers
snoun in an annex are defined by circular no 16 of 4 October

The rear zone of a limited traffic international center consists
of the regional transit zone (or the transit zone) of the transit
center with which it is associated. This definition covers
originating and incoming traffic.

39



discrimination. The number of prefixes (AB, PQ, and ABPQ)
that can thus be constructed is a minimum of 20 combinations
(80 gates). 7

The results indicated (time and number of calls) are. only
calls of which a complete observation was done. However, the
recording does indicate the total number of calls from which
those that had a complete observation done were taken.

Manual Observation

When the analyzer is connected to incoming junctors, it is
possible to make a manual observation of calls. In this case,
the call observed will not be counted by the observation de-
vice. This device will only analyze the number called, possibly
to reject observation of this call and to move on to the fol-
lowing call.

A lamp is associated with each of the ten lines observed; it
ignites upon. connection of the observation line and goes out
upon disconnection of this line by the observation device (only
one of the ten lamps giving the number of the observation line
which is working with the device is lit).

The operator can use a key to maintain a discreet monitoring on
a loudspeaker. There are three possible cases:

First case: intervention on a call during observation.

The call is handled by the device as in the case of recording.
Nonetheless, the operator may follow the operations on a light
signal for the number called and on a loudspeaker for the con-
versation.

The calls which follow will be observed by the operator while
the manual observation key is down and will not be recorded on
time totalizers or on the other call counters. There will be
no recording per ten calls occurring in the operator's presence.
Second case: intervention at the start of a call.

The call will be followed by the operator and the observation
device is involved only in authorizing or rejecting observation.

Third case: the operator withdraws during observation of a call.

a. If the operator intervenes when observation has already
started, the device continues its automatic observation.

25



5.2126. Incoming junctors of CT2-CT+ links (line F of
table).

Links between CT2 and CT4 are three-wire links. The third wire
is used for retransmission of supervision.

The maximum resistance of each wire between dispatchers must not
exceed 500 Q.

5.2127. Incoming junctors for switchboard call line,
national line, of the manual long-distance system associated
with CT2, national positions (line G of table).

These are three-wire links. The third wire is used for retrans-
mission of supervision.

The maximum resistance of each wire between dispatchers must
not exceed 500 2.

5.213. Incoming junctors served by incoming registers.

5.2131. Incomiing junctors of automatic long-distance
eircuits Clines C and D of table).

All these circuits come from the amplification center. Each
link has six wires:

a. two wires for sending
b. two wires for return
c. two signaling wires (RON and TRON)

The junctors may be used to equip the circuits operated either in
decimal numbered code or in MF SOCOTEL code.

The maximum resistance of each wire between the dispatcher of
the amplification center and the dispatcher of the CT+ must not
exceed 300 Q.

"In all cases in which a communication is established, the
acceptable intensity on the RON wire (reception) must be less
than 50 mA, no matter what the receiving equipment used. All
reasonable precautions must be taken to protect the control con-
tact of the amplification center (varistor or spark arrester

in a parallel arrangement on the receiving relay)."

5.2132. Junctors for switchboard call lines for operators
of the manual center associated with CT4 (line K of table).



Al.3. Sub-center,

Al.31.

Connection center Links
(Sector center, intermediate, or group center)

Status code (direct current)

Connection center to sub-center

Phase Connection center Sub-center
Rest 670 SL loop 6002 loop
Connection Ground on A; 6002 loop

Good circuit

Request to
transmit

Numbering
Busy

Ringing
Call release

battery on B,
220. per wire

Power supply
Power supply

Opening of 50/50
power supply

Power supply

Power supply

Opening of 200 ms
power supply

12,000/2 loop
5002 loop

50011 loop

Ground or + 48 V at
mid-point of 5001
loop

12,0002 100p

12,000 loop

Response Power supply 600 S21 loop
requested
Hang-up Power supply 12,0002 loop
requested
Call back Opening of 200 ms 12,0002 loop
power supply
Disconnect Definitive opening
of power supply
then loop
Comments:
1. In the case of the SRCT sub-center, there is an opening

of the loop (12,5001 loop) during the selection; the
second digit (unity digit) can only be sent when the
500SLloop is reestablished.
2. In the case of a crossbar sub-center, there may or may

not be loop opening between digits.

3. The busy signal (ground at mid-point in SRCT, + 48 V at
mid-point in SOCOTEL-S1) is replaced after 200 ms by a

strong loop.

61



In this way each end transmits or receives signals according to
a program determined by using signal codes. ‘The same signaling
frequencies may therefore be used forward and backward. The
monitoring of sending a signal is done by the frequency fe, and
the program is such that a transmission of fc must never respond
to a transmission of fe:

A3.24. Signal codes

They include either the forward or backward signals indicated in
the corresponding tables. Some signals without a particular
denomination are kept in reserve for future requirements of
national or international operation. The abbreviations of the
signals indicate their essential meaning. Their use calls for
the following remarks:

A3.25. Forward signals

There are three types of forward signals: signals corresponding
to the digits to be transmitted (numerical code), preliminary
recognition signals indicating the nature of the communication
to be established (access code, with one of the last signals
necessarily preceding the sending of the first digits of the
number being called), and signals corresponding to the category
of the caller.

Signals of the numerical code are used to transmit selection
information; they are also used (upon request for a C signal
backward after passage to code C) to transmit information con-
cerning the caller.

Comments concerning these different signals are given below,
during the examination of the backward signals requesting the
corresponding information.

The use of signals reserved for international traffic is given
later.

A3.26. Backward signals.
These signals have been classified in three categories: A, B,
and C, based on the data concerning selection, status of the
line called, identification of the caller, respectively.
A3.261. A Signals

These signals are used to request or to transmit information
needed for selection.

77



Key for figures:

CU: urban automatic switcher

CTU: urban transit center

CR: connection link for automatic group switchers
(SRCT, 81) oe

Cet I: international circuit

CIM: manual international center

F.sp.: circuit of specialized beam
CIAT: international head of the line center

Figure 2.

If the communication is entirely automatic and is destined for
a country accessible from another automatic international center
(which is necessarily an automatic international center for
general traffic), either in normal channels, or on overload
channels, the call is routed from the originating international
center on a beam of specialized circuits ending at the head of
the line international center (figure 2). This beam of circuits
is operated in an international code..

The beam of specialized circuits also routes communications for
distant manual international centers. The call is preceded by
the "transit connection" signal followed by 33 (0) XY if it is

coming from a subscriber, and 33 L XY C 15 if it is coming from
an operator.

6.412. Communications originating from transit centers
and group centers of the regional transit zone
of the CIA (excluding the CIA group center).

6.4121. The center has a CLI.

47



Circuits between the local international link and the inter-
national center CIA 1 are operated in international code.

6.4122. The center has an international access link.

It has a beam of direct circuits with the automatic interna-
tional center or, if the distance and the traffic do not warrant
such a beam, with a. transit. center equipped with a CLI. Commu-
nications are charged by the international center or by the local
international link and the charge pulses are retransmitted on

a transmission channel adapted for this purpose. (Figures 5

and .

ClAy Cet |
CG
(ch Al) CIM Clay Cet I
F.sp rs
oy, CIM
\
ee = \
.
naa F.sp
Figure 5.

Figure 6.
6.42. The CTR is equipped with a local international link.
6.421. Communications originating from a subscriber of
the group center and from the group of regional
transit centers equipped with a local international
link.

49



register to make a new connection after reception of the third,
the fourth, or the fifth digit. If the number of digits is

still inadequate, the translator indicates to the register that
a third connection must be made after the fourth or fifth digit.

The translator may then be contacted again as the need arises
during routing the call, in the following conditions:

b. Six categories concerning the origin of the call
(circuit of the auxiliary line or group, circuit outside the
group, incorrect call, operator, incomplete number, available);

ce. Two indications concerning the routing of the call
(routing on a normal channel, routing on overload channel);

d. Two indications concerning the number received (re-
gional number, national number);

e. Possibly indications concerning selection phases.
5.2315. Internal selections
a. Normal procedure

The translator transmits the code marking the address called
and, to the register, information on the possibility of using
an overload for the register.

The process may begin again for a second selection. It leads
to a second contact of translator to receive the marking code
for the second selection.

Then the register receives the category indication of the
outgoing junctor:

link with local network

no later selection

interautomatic SOCOTEL multifrequency code
SOCOTEL urban multifrequency code
interautomatic decimal code

decimal selection last three digits (CDU)
three possibilities

b. Overload
Overload by marker

The selection is first made in a first beam. If it does not
get through within a period of time determined by the operation

12